<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.4 20241031//EN" "JATS-journalpublishing1-4.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="1.4" xml:lang="en">
  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">ojgas</journal-id>
      <journal-title-group>
        <journal-title>Open Journal of Gastroenterology</journal-title>
      </journal-title-group>
      <issn pub-type="epub">2163-9469</issn>
      <issn pub-type="ppub">2163-9450</issn>
      <publisher>
        <publisher-name>Scientific Research Publishing</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.4236/ojgas.2026.164015</article-id>
      <article-id pub-id-type="publisher-id">ojgas-150771</article-id>
      <article-categories>
        <subj-group>
          <subject>Article</subject>
        </subj-group>
        <subj-group>
          <subject>Medicine</subject>
          <subject>Healthcare</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Association between C-Reactive Protein, Fecal Calprotectin, and Endoscopic Disease Activity in Patients with Inflammatory Bowel Disease</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0009-0001-4338-7327</contrib-id>
          <name name-style="western">
            <surname>Bentabet</surname>
            <given-names>Samia</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <name name-style="western">
            <surname>Abed</surname>
            <given-names>Oumaima El</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <name name-style="western">
            <surname>Yousfi</surname>
            <given-names>Mounia El</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <name name-style="western">
            <surname>Abkari</surname>
            <given-names>Mohammed El</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <name name-style="western">
            <surname>Ibrahimi</surname>
            <given-names>Sidi Adil</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <name name-style="western">
            <surname>Lahmidani</surname>
            <given-names>Nada</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
      </contrib-group>
      <aff id="aff1"><label>1</label> Department of Hepato-Gastroenterology, Hassan II University Hospital, Fez, Morocco </aff>
      <aff id="aff2"><label>2</label> Faculty of Medicine and Pharmacy, Sidi Mohammed Ben Abdellah University, Fez, Morocco </aff>
      <author-notes>
        <fn fn-type="conflict" id="fn-conflict">
          <p>The authors declare no conflicts of interest regarding the publication of this paper.</p>
        </fn>
      </author-notes>
      <pub-date pub-type="epub">
        <day>02</day>
        <month>04</month>
        <year>2026</year>
      </pub-date>
      <pub-date pub-type="collection">
        <month>04</month>
        <year>2026</year>
      </pub-date>
      <volume>16</volume>
      <issue>04</issue>
      <fpage>138</fpage>
      <lpage>147</lpage>
      <history>
        <date date-type="received">
          <day>07</day>
          <month>03</month>
          <year>2026</year>
        </date>
        <date date-type="accepted">
          <day>13</day>
          <month>04</month>
          <year>2026</year>
        </date>
        <date date-type="published">
          <day>16</day>
          <month>04</month>
          <year>2026</year>
        </date>
      </history>
      <permissions>
        <copyright-statement>© 2026 by the authors and Scientific Research Publishing Inc.</copyright-statement>
        <copyright-year>2026</copyright-year>
        <license license-type="open-access">
          <license-p> This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link> ). </license-p>
        </license>
      </permissions>
      <self-uri content-type="doi" xlink:href="https://doi.org/10.4236/ojgas.2026.164015">https://doi.org/10.4236/ojgas.2026.164015</self-uri>
      <abstract>
        <p><bold>Background:</bold> Endoscopic evaluation is considered the reference method for assessing inflammatory activity in inflammatory bowel disease (IBD) [<xref ref-type="bibr" rid="B1">1</xref>]. Nevertheless, the invasive nature and cost of repeated endoscopic procedures limit their use for frequent monitoring in routine clinical practice [<xref ref-type="bibr" rid="B2">2</xref>]. In this context, non-invasive biomarkers such as C-reactive protein (CRP) and fecal calprotectin (FC) have been increasingly used to estimate intestinal inflammatory activity [<xref ref-type="bibr" rid="B3">3</xref>]. <bold>Aim:</bold> To examine the relationship between CRP, fecal calprotectin, and endoscopic disease activity in patients with IBD, and to determine the diagnostic performance of their combined use. <bold>Methods:</bold> This cross-sectional observational study included 180 adult patients with confirmed IBD who underwent recent endoscopic evaluation along with concomitant measurements of CRP and fecal calprotectin. Endoscopic activity was assessed using the Simple Endoscopic Score for Crohn’s Disease (SES-CD) for Crohn’s disease and the Mayo endoscopic subscore for ulcerative colitis. Associations between biomarker levels and endoscopic scores were analyzed using Spearman’s rank correlation coefficient. <bold>Results:</bold> A total of 180 patients were included, of whom 120 had Crohn’s disease, and 60 had ulcerative colitis. Fecal calprotectin demonstrated strong correlations with endoscopic activity in Crohn’s disease (r = 0.74, <italic>p</italic> &lt; 0.001) and ulcerative colitis (r = 0.69, <italic>p</italic> &lt; 0.001). In comparison, CRP showed moderate correlations with endoscopic severity (r = 0.48 and r = 0.42, respectively). The combined evaluation of CRP and fecal calprotectin improved the identification of moderate-to-severe endoscopic inflammation, with a sensitivity of 88% and a specificity of 76%. <bold>Conclusion:</bold> Fecal calprotectin shows a strong association with endoscopic disease activity and appears to be more informative than CRP for reflecting mucosal inflammation in patients with IBD.</p>
      </abstract>
      <kwd-group kwd-group-type="author-generated" xml:lang="en">
        <kwd>Inflammatory Bowel Disease</kwd>
        <kwd>Crohn’s Disease</kwd>
        <kwd>Ulcerative Colitis</kwd>
        <kwd>Fecal Calprotectin</kwd>
        <kwd>C-Reactive Protein</kwd>
        <kwd>Endoscopic Activity</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec1">
      <title>1. Introduction</title>
      <p>Inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic inflammatory conditions characterized by alternating periods of remission and relapse. Continuous assessment of disease activity is essential for guiding therapeutic decisions and optimizing patient outcomes [<xref ref-type="bibr" rid="B1">1</xref>]. In recent years, mucosal healing has become a central therapeutic objective because it is associated with lower relapse rates, reduced hospitalization, and improved long-term prognosis [<xref ref-type="bibr" rid="B2">2</xref>][<xref ref-type="bibr" rid="B3">3</xref>].</p>
      <p>Endoscopic evaluation remains the reference method for directly assessing intestinal inflammation and mucosal lesions in patients with IBD [<xref ref-type="bibr" rid="B4">4</xref>]. However, repeated endoscopic procedures are invasive, costly, and sometimes poorly tolerated by patients, which limits their use for frequent monitoring during routine follow-up [<xref ref-type="bibr" rid="B5">5</xref>].</p>
      <p>For this reason, increasing attention has been directed toward the use of non-invasive biomarkers to evaluate intestinal inflammatory activity. C-reactive protein (CRP) is widely used as a marker of systemic inflammation, although its ability to reflect intestinal disease activity is variable [<xref ref-type="bibr" rid="B6">6</xref>]. In contrast, fecal calprotectin, a neutrophil-derived protein released into the intestinal lumen during inflammation, has emerged as a sensitive and specific marker of mucosal inflammatory activity in IBD [<xref ref-type="bibr" rid="B7">7</xref>]-[<xref ref-type="bibr" rid="B10">10</xref>].</p>
      <p>Several studies have reported strong associations between fecal calprotectin levels and endoscopic disease activity and have highlighted its potential value for predicting relapse and monitoring response to therapy [<xref ref-type="bibr" rid="B11">11</xref>]-[<xref ref-type="bibr" rid="B14">14</xref>]. Furthermore, recent international recommendations emphasize the role of biomarker-based monitoring strategies as part of treat-to-target approaches in the management of inflammatory bowel disease [<xref ref-type="bibr" rid="B15">15</xref>]-[<xref ref-type="bibr" rid="B19">19</xref>].</p>
      <p>The aim of the present study was to evaluate the relationship between CRP, fecal calprotectin, and endoscopic disease activity in patients with inflammatory bowel disease, and to assess the diagnostic performance of their combined use.</p>
    </sec>
    <sec id="sec2">
      <title>2. Materials and Methods</title>
      <sec id="sec2dot1">
        <title>2.1. Study Design and Setting</title>
        <p>This cross-sectional observational study was conducted at the Department of Hepato-Gastroenterology, Hassan II University Hospital, Fez, Morocco.</p>
      </sec>
      <sec id="sec2dot2">
        <title>2.2. Study Population</title>
        <p>A total of 180 adult patients with confirmed inflammatory bowel disease were included between January 2019 and January 2025, comprising:</p>
        <p>120 patients with Crohn’s disease.60 patients with ulcerative colitis.</p>
        <p>All patients were enrolled consecutively at the Department of Hepato-Gastroenterology of Hassan II University Hospital, Fez, Morocco.</p>
        <p>The maximum allowed interval between endoscopic assessment and biomarker measurement (CRP and fecal calprotectin) was 14 days. Only patients with both evaluations performed within this timeframe were included to ensure temporal consistency.</p>
        <p><bold>Inclusion</bold><bold>Criteria</bold></p>
        <p>Patients were eligible if they met the following criteria:</p>
        <p>Age ≥ 18 years.Confirmed diagnosis of Crohn’s disease or ulcerative colitis.Recent colonoscopy or rectosigmoidoscopy.Concurrent measurement of CRP and fecal calprotectin.</p>
        <p><bold>Exclusion</bold><bold>Criteria</bold></p>
        <p>Included patients with acute infections, recent gastrointestinal surgery (&lt;3 months), known colorectal cancer, use of nonsteroidal anti-inflammatory drugs within the previous 2 weeks, or incomplete clinical or biological data.</p>
      </sec>
      <sec id="sec2dot3">
        <title>2.3. Endoscopic Activity Definitions</title>
        <p>In Crohn’s disease, endoscopic activity was assessed using the Simple Endoscopic Score for Crohn’s Disease (SES-CD), with moderate-to-severe activity defined as SES-CD ≥ 7.</p>
        <p>In ulcerative colitis, endoscopic activity was assessed using the Mayo endoscopic subscore, with moderate-to-severe activity defined as a Mayo score ≥ 2.</p>
      </sec>
      <sec id="sec2dot4">
        <title>2.4. Biomarker Assessment</title>
        <p>Elevated CRP was defined as &gt;5 mg/L, and elevated fecal calprotectin (FC) as &gt;250 µg/g.</p>
        <p>The combined CRP + FC test was considered positive when both markers were elevated simultaneously.</p>
      </sec>
      <sec id="sec2dot5">
        <title>2.5. Endoscopic Assessment</title>
        <p>Endoscopic disease activity was evaluated using:</p>
        <p>SES-CD for Crohn’s disease.Mayo endoscopic subscore for ulcerative colitis.</p>
        <p>Moderate-to-severe activity was defined as:</p>
        <p>SES-CD ≥ 7.Mayo score ≥ 2.</p>
      </sec>
      <sec id="sec2dot6">
        <title>2.6. Biomarker Measurement</title>
        <p>CRP levels were measured in serum, with elevated levels defined as &gt;5 mg/L.</p>
        <p>Fecal calprotectin was measured using standardized assays, with elevated levels defined as &gt;250 µg/g.</p>
        <p>The combined CRP + FC test was considered positive when both markers were elevated.</p>
      </sec>
      <sec id="sec2dot7">
        <title>2.7. Statistical Analysis</title>
        <p>Continuous variables were expressed as mean ± standard deviation. Correlations between biomarkers and endoscopic scores were evaluated using Spearman’s rank correlation coefficient. Statistical analyses were performed using SPSS software. A two-sided <italic>p</italic>-value &lt; 0.05 was considered statistically significant.</p>
      </sec>
    </sec>
    <sec id="sec3">
      <title>3. Results</title>
      <sec id="sec3dot1">
        <title>3.1. Patient Characteristics</title>
        <p>A total of 180 patients with confirmed inflammatory bowel disease were included in the study. The mean age of the study population was 34.2 years, with a predominance of female patients (58%). Crohn’s disease represented the majority of cases, accounting for 120 patients (66.7%), whereas 60 patients (33.3%) were diagnosed with ulcerative colitis.</p>
        <p>The baseline characteristics of the study population are summarized in <bold>Table 1</bold>.</p>
        <p><bold>Table 1.</bold> Baseline characteristics of the study population.</p>
        <table-wrap id="tbl1">
          <label>Table 1</label>
          <table>
            <tbody>
              <tr>
                <td>
                  <bold>Variable</bold>
                </td>
                <td>
                  <bold>Value</bold>
                </td>
              </tr>
              <tr>
                <td>Total patients</td>
                <td>180</td>
              </tr>
              <tr>
                <td>Mean age</td>
                <td>34.2</td>
              </tr>
              <tr>
                <td>Female</td>
                <td>105 (58%)</td>
              </tr>
              <tr>
                <td>Male</td>
                <td>75 (42%)</td>
              </tr>
              <tr>
                <td>Crohn’s disease</td>
                <td>120 (66.7%)</td>
              </tr>
              <tr>
                <td>Ulcerative colitis</td>
                <td>60 (33.3%)</td>
              </tr>
            </tbody>
          </table>
        </table-wrap>
        <p>Among patients with Crohn’s disease, ileal involvement (L1) was observed in 38%, colonic involvement (L2) in 27%, and ileocolonic disease (L3) in 35% of cases.</p>
        <p>In patients with ulcerative colitis, left-sided colitis represented the most frequent disease extent (41%), followed by pancolitis (37%) and proctitis (22%).</p>
      </sec>
      <sec id="sec3dot2">
        <title>3.2. Biomarker Levels according to Endoscopic Activity</title>
        <p><bold>Crohn</bold><bold>’</bold><bold>s</bold><bold>Disease</bold><bold>:</bold> In patients with Crohn’s disease, Active endoscopic inflammation (SES-CD ≥ 7) was associated with significantly higher levels of inflammatory biomarkers compared with inactive disease.</p>
        <p>Mean CRP levels were 26.4 mg/L in patients with active disease compared with 8.2 mg/L in those with inactive disease. Similarly, fecal calprotectin concentrations were markedly elevated in active disease (780 µg/g) compared with inactive disease (190 µg/g).</p>
        <p>Detailed biomarker levels according to endoscopic activity are presented in <bold>Table 2</bold>.</p>
        <p><bold>Table 2.</bold> Biomarker levels according to endoscopic activity.</p>
        <table-wrap id="tbl2">
          <label>Table 2</label>
          <table>
            <tbody>
              <tr>
                <td>
                  <bold>Disease</bold>
                </td>
                <td>
                  <bold>Endoscopic</bold>
                  <bold>Activity</bold>
                </td>
                <td>
                  <bold>CRP</bold>
                  <bold>(mg/L)</bold>
                </td>
                <td>
                  <bold>Fecal</bold>
                  <bold>Calprotectin</bold>
                  <bold>(µg/g)</bold>
                </td>
              </tr>
              <tr>
                <td>Crohn’s disease</td>
                <td>Active</td>
                <td>26.4</td>
                <td>780</td>
              </tr>
              <tr>
                <td>Crohn’s disease</td>
                <td>Inactive</td>
                <td>8.2</td>
                <td>190</td>
              </tr>
              <tr>
                <td>Ulcerative colitis</td>
                <td>Active</td>
                <td>12.8</td>
                <td>720</td>
              </tr>
              <tr>
                <td>Ulcerative colitis</td>
                <td>Remission</td>
                <td>5.6</td>
                <td>210</td>
              </tr>
            </tbody>
          </table>
        </table-wrap>
        <p>These findings indicate that patients with active mucosal inflammation present markedly higher biomarker levels compared with those in endoscopic remission.</p>
      </sec>
      <sec id="sec3dot3">
        <title>3.3. Correlation between Biomarkers and Endoscopic Activity</title>
        <p>Correlation analysis demonstrated a significant association between biomarker levels and endoscopic disease severity in both Crohn’s disease and ulcerative colitis.</p>
        <p>The correlation coefficients between biomarkers and endoscopic activity scores are summarized in <bold>Table 3</bold>.</p>
        <p><bold>Table 3.</bold> Correlation between biomarkers and endoscopic activity scores.</p>
        <table-wrap id="tbl3">
          <label>Table 3</label>
          <table>
            <tbody>
              <tr>
                <td>
                  <bold>Biomarker</bold>
                </td>
                <td>
                  <bold>Crohn’s</bold>
                  <bold>Disease</bold>
                  <bold>(SES-CD)</bold>
                </td>
                <td>
                  <bold>Ulcerative</bold>
                  <bold>Colitis</bold>
                  <bold>(Mayo</bold>
                  <bold>score)</bold>
                </td>
              </tr>
              <tr>
                <td>Fecal calprotectin</td>
                <td>
                  r = 0.74 (
                  <italic>p</italic>
                  &lt; 0.001)
                </td>
                <td>
                  r = 0.69 (
                  <italic>p</italic>
                  &lt; 0.001)
                </td>
              </tr>
              <tr>
                <td>C-reactive protein</td>
                <td>
                  r = 0.48 (
                  <italic>p</italic>
                  &lt; 0.001)
                </td>
                <td>
                  r = 0.42 (
                  <italic>p</italic>
                  = 0.002)
                </td>
              </tr>
            </tbody>
          </table>
        </table-wrap>
        <p>Fecal calprotectin demonstrated strong correlations with endoscopic disease activity in both disease phenotypes. In Crohn’s disease, the correlation between fecal calprotectin and SES-CD score was r = 0.74, whereas CRP showed a moderate correlation (r = 0.48).</p>
        <p>Similarly, in ulcerative colitis, fecal calprotectin showed a strong correlation with the Mayo endoscopic score (r = 0.69), while CRP demonstrated a weaker correlation (r = 0.42).</p>
        <p>Overall, fecal calprotectin showed consistently stronger correlations with endoscopic disease severity than CRP, suggesting that fecal calprotectin more accurately reflects intestinal inflammatory activity.</p>
      </sec>
      <sec id="sec3dot4">
        <title>3.4. Ulcerative Colitis</title>
        <p>In patients with ulcerative colitis, active disease (defined as Mayo score 2 - 3) was associated with higher biomarker levels compared with patients in endoscopic remission (Mayo score 0 - 1).</p>
        <p>Mean CRP levels were 12.8 mg/L in active disease compared with 5.6 mg/L in remission. Fecal calprotectin concentrations were also significantly higher in active disease (720 µg/g) compared with remission (210 µg/g), as shown in <bold>Table 2</bold>.</p>
        <p>These findings further support the role of fecal calprotectin as a marker of mucosal inflammation in ulcerative colitis.</p>
      </sec>
      <sec id="sec3dot5">
        <title>3.5. Combined Diagnostic Performance</title>
        <p>The combined evaluation of CRP and fecal calprotectin improved the detection of clinically significant endoscopic inflammation.</p>
        <p>The diagnostic performance of the combined biomarker approach for identifying moderate-to-severe endoscopic activity showed:</p>
        <p>Sensitivity: 88%.Specificity: 76%.</p>
        <p>These results suggest that the combined use of CRP and fecal calprotectin may improve the identification of patients with active intestinal inflammation and may help guide decisions regarding the need for endoscopic reassessment.</p>
      </sec>
    </sec>
    <sec id="sec4">
      <title>4. Discussion</title>
      <p>The present study demonstrates that fecal calprotectin is strongly associated with endoscopic disease activity in patients with inflammatory bowel disease and shows a stronger correlation with mucosal inflammation than C-reactive protein. These findings support the growing evidence that fecal calprotectin represents a reliable non-invasive biomarker for assessing intestinal inflammatory activity in both Crohn’s disease and ulcerative colitis.</p>
      <p>Fecal calprotectin is a calcium-binding protein predominantly derived from neutrophils and released during intestinal inflammation. Because it directly reflects neutrophil migration into the intestinal lumen, its concentration in stool correlates closely with the degree of mucosal inflammatory burden [<xref ref-type="bibr" rid="B6">6</xref>][<xref ref-type="bibr" rid="B7">7</xref>]. In contrast, CRP is a systemic acute-phase reactant produced by hepatocytes in response to inflammatory cytokines such as interleukin-6. Although CRP is widely used in clinical practice due to its accessibility and low cost, it may underestimate localized intestinal inflammation, particularly in ulcerative colitis, where inflammation is often limited to the mucosal layer [<xref ref-type="bibr" rid="B5">5</xref>][<xref ref-type="bibr" rid="B20">20</xref>].</p>
      <p>Our findings are consistent with several previous investigations demonstrating a strong association between fecal calprotectin levels and endoscopic disease severity in IBD [<xref ref-type="bibr" rid="B21">21</xref>]-[<xref ref-type="bibr" rid="B24">24</xref>]. In particular, Schoepfer <italic>et al.</italic> [<xref ref-type="bibr" rid="B12">12</xref>] showed that fecal calprotectin correlates more closely with endoscopic activity than CRP in patients with ulcerative colitis. Similarly, Sipponen <italic>et al.</italic> [<xref ref-type="bibr" rid="B11">11</xref>] reported a significant relationship between fecal calprotectin concentrations and endoscopic lesions in Crohn’s disease. Meta-analyses have also confirmed the high diagnostic accuracy of fecal calprotectin for detecting active intestinal inflammation and predicting mucosal lesions [<xref ref-type="bibr" rid="B23">23</xref>].</p>
      <p>In the present study, fecal calprotectin demonstrated strong correlations with endoscopic scores in both Crohn’s disease and ulcerative colitis. These findings reinforce its role as a surrogate marker of mucosal inflammation. Because fecal calprotectin reflects intestinal neutrophilic inflammation directly at the mucosal level, it provides a more specific indicator of intestinal disease activity than systemic inflammatory markers.</p>
      <p>Interestingly, the strength of correlation between fecal calprotectin and endoscopic activity was slightly higher in Crohn’s disease compared with ulcerative colitis. This observation may be explained by differences in disease phenotype and inflammatory burden. Crohn’s disease is characterized by transmural inflammation and often involves extensive segments of the gastrointestinal tract, which may lead to higher levels of inflammatory biomarkers and stronger correlations with objective measures of disease activity.</p>
      <p>Another important finding of this study is the improved diagnostic performance observed when CRP and fecal calprotectin were evaluated together. The combined biomarker strategy achieved a sensitivity of 88% and specificity of 76% for detecting moderate-to-severe endoscopic activity. This suggests that integrating multiple biomarkers may enhance the identification of patients with clinically significant inflammation and support decision-making regarding the need for endoscopic reassessment. Multimarker monitoring strategies have increasingly been proposed to improve disease assessment and guide therapeutic decisions in IBD management [<xref ref-type="bibr" rid="B25">25</xref>]-[<xref ref-type="bibr" rid="B28">28</xref>].</p>
      <p>From a clinical perspective, the use of fecal calprotectin as a non-invasive monitoring tool may help reduce the need for frequent endoscopic procedures, improve patient comfort, and facilitate closer disease surveillance. Biomarker-guided monitoring strategies may also support treat-to-target approaches that aim to achieve mucosal healing and optimize long-term outcomes in patients with IBD [<xref ref-type="bibr" rid="B29">29</xref>][<xref ref-type="bibr" rid="B30">30</xref>].</p>
      <p>However, several limitations of this study should be acknowledged. First, the cross-sectional design does not allow evaluation of longitudinal changes in biomarker levels or their predictive value for relapse and therapeutic response. Prospective longitudinal studies would be necessary to determine whether fecal calprotectin can reliably predict disease relapse or guide treatment adjustments. Second, although fecal calprotectin is widely used in clinical practice, there is currently no universally standardized cut-off value applicable across different patient populations and assay methods.</p>
      <p>Despite these limitations, our study has several strengths. The use of validated endoscopic scoring systems, including the SES-CD for Crohn’s disease and the Mayo endoscopic subscore for ulcerative colitis, ensured objective assessment of mucosal disease activity. In addition, biomarker measurements were obtained concurrently with endoscopic evaluation, allowing accurate correlation analysis. Finally, the study was conducted in a real-world tertiary care cohort, reflecting routine clinical practice and enhancing the clinical applicability of the findings.</p>
      <p>Overall, our results reinforce the value of fecal calprotectin as a key biomarker for assessing intestinal inflammation in inflammatory bowel disease and support its integration into non-invasive monitoring strategies.</p>
      <p>These findings are consistent with current international treat-to-target strategies for inflammatory bowel disease management. According to the STRIDE-II recommendations, objective assessment of inflammation using biomarkers such as fecal calprotectin is strongly encouraged to guide treatment decisions and monitor therapeutic response.</p>
      <p>Recent guidelines from the American Gastroenterological Association further support the use of fecal calprotectin and CRP as non-invasive tools for monitoring disease activity and guiding therapeutic decisions in both ulcerative colitis and Crohn’s disease [<xref ref-type="bibr" rid="B31">31</xref>][<xref ref-type="bibr" rid="B32">32</xref>].</p>
    </sec>
    <sec id="sec5">
      <title>5. Conclusions</title>
      <p>In this study of 180 patients with inflammatory bowel disease, fecal calprotectin showed stronger correlations with endoscopic activity than C-reactive protein in both Crohn’s disease (r = 0.74 vs 0.48) and ulcerative colitis (r = 0.69 vs 0.42). Patients with active disease exhibited markedly higher biomarker levels.</p>
      <p>The combined use of fecal calprotectin and CRP improved detection of moderate-to-severe endoscopic activity, with 88% sensitivity and 76% specificity. These findings support fecal calprotectin as a reliable non-invasive biomarker for monitoring intestinal inflammation and optimizing the use of endoscopy in IBD follow-up.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <title>References</title>
      <ref id="B1">
        <label>1.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Ng, S.C., Shi, H.Y., Hamidi, N., Underwood, F.E., Tang, W., Benchimol, E.I., <italic>et al</italic>. (2017) Worldwide Incidence and Prevalence of Inflammatory Bowel Disease in the 21st Century: A Systematic Review of Population-Based Studies. <italic>The</italic><italic>Lancet</italic>, 390, 2769-2778. https://doi.org/10.1016/s0140-6736(17)32448-0 <pub-id pub-id-type="doi">10.1016/s0140-6736(17)32448-0</pub-id><pub-id pub-id-type="pmid">29050646</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/s0140-6736(17)32448-0">https://doi.org/10.1016/s0140-6736(17)32448-0</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Ng, S.C.</string-name>
              <string-name>Shi, H.Y.</string-name>
              <string-name>Hamidi, N.</string-name>
              <string-name>Underwood, F.E.</string-name>
              <string-name>Tang, W.</string-name>
              <string-name>Benchimol, E.I.</string-name>
            </person-group>
            <year>2017</year>
            <article-title>Worldwide Incidence and Prevalence of Inflammatory Bowel Disease in the 21st Century: A Systematic Review of Population-Based Studies</article-title>
            <source>The Lancet</source>
            <volume>6736</volume>
            <issue>17</issue>
            <pub-id pub-id-type="doi">10.1016/s0140-6736(17)32448-0</pub-id>
            <pub-id pub-id-type="pmid">29050646</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B2">
        <label>2.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Colombel, J., Narula, N. and Peyrin-Biroulet, L. (2017) Management Strategies to Improve Outcomes of Patients with Inflammatory Bowel Diseases. <italic>Gastroenterology</italic>, 152, 351-361.e5. https://doi.org/10.1053/j.gastro.2016.09.046 <pub-id pub-id-type="doi">10.1053/j.gastro.2016.09.046</pub-id><pub-id pub-id-type="pmid">27720840</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/j.gastro.2016.09.046">https://doi.org/10.1053/j.gastro.2016.09.046</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Colombel, J.</string-name>
              <string-name>Narula, N.</string-name>
              <string-name>Peyrin-Biroulet, L.</string-name>
            </person-group>
            <year>2017</year>
            <article-title>Management Strategies to Improve Outcomes of Patients with Inflammatory Bowel Diseases</article-title>
            <source>Gastroenterology</source>
            <volume>152</volume>
            <pub-id pub-id-type="doi">10.1053/j.gastro.2016.09.046</pub-id>
            <pub-id pub-id-type="pmid">27720840</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B3">
        <label>3.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Peyrin-Biroulet, L., Sandborn, W.J., Sands, B.E., Reinisch, W., Bemelman, W., Bryant, R.V., <italic>et al</italic>. (2015) Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE). <italic>Gastroenterology</italic>, 148, 1210-1219.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Peyrin-Biroulet, L.</string-name>
              <string-name>Sandborn, W.J.</string-name>
              <string-name>Sands, B.E.</string-name>
              <string-name>Reinisch, W.</string-name>
              <string-name>Bemelman, W.</string-name>
              <string-name>Bryant, R.V.</string-name>
            </person-group>
            <year>2015</year>
            <article-title>Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE)</article-title>
            <source>Gastroenterology</source>
            <volume>148</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B4">
        <label>4.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Maaser, C., Sturm, A., Vavricka, S.R., Kucharzik, T., Fiorino, G., Annese, V., <italic>et al</italic>. (2018) ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial Diagnosis, Monitoring of Known IBD, Detection of Complications. <italic>Journal</italic><italic>of</italic><italic>Crohn</italic>’ <italic>s</italic><italic>and</italic><italic>Colitis</italic>, 13, 144-164K. https://doi.org/10.1093/ecco-jcc/jjy113 <pub-id pub-id-type="doi">10.1093/ecco-jcc/jjy113</pub-id><pub-id pub-id-type="pmid">30137275</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1093/ecco-jcc/jjy113">https://doi.org/10.1093/ecco-jcc/jjy113</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Maaser, C.</string-name>
              <string-name>Sturm, A.</string-name>
              <string-name>Vavricka, S.R.</string-name>
              <string-name>Kucharzik, T.</string-name>
              <string-name>Fiorino, G.</string-name>
              <string-name>Annese, V.</string-name>
              <string-name>Diagnosis, M</string-name>
              <string-name>IBD, D</string-name>
            </person-group>
            <year>2018</year>
            <article-title>ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial Diagnosis, Monitoring of Known IBD, Detection of Complications</article-title>
            <source>Journal of Crohn’s and Colitis</source>
            <volume>13</volume>
            <pub-id pub-id-type="doi">10.1093/ecco-jcc/jjy113</pub-id>
            <pub-id pub-id-type="pmid">30137275</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B5">
        <label>5.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Vermeire, S., Van Assche, G. and Rutgeerts, P. (2006) Laboratory Markers in IBD: Useful, Magic, or Unnecessary Toys? <italic>Gut</italic>, 55, 426-431. https://doi.org/10.1136/gut.2005.069476 <pub-id pub-id-type="doi">10.1136/gut.2005.069476</pub-id><pub-id pub-id-type="pmid">16474109</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1136/gut.2005.069476">https://doi.org/10.1136/gut.2005.069476</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Vermeire, S.</string-name>
              <string-name>Assche, G.</string-name>
              <string-name>Rutgeerts, P.</string-name>
              <string-name>Useful, M</string-name>
            </person-group>
            <year>2006</year>
            <article-title>Laboratory Markers in IBD: Useful, Magic, or Unnecessary Toys? Gut, 55, 426-431</article-title>
            <pub-id pub-id-type="doi">10.1136/gut.2005.069476</pub-id>
            <pub-id pub-id-type="pmid">16474109</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B6">
        <label>6.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Henriksen, M., Jahnsen, J., Lygren, I., Stray, N., Sauar, J., Vatn, M.H., <italic>et al</italic>. (2008) C-reactive Protein: A Predictive Factor and Marker of Inflammation in Inflammatory Bowel Disease. Results from a Prospective Population-Based Study. <italic>Gut</italic>, 57, 1518-1523. https://doi.org/10.1136/gut.2007.146357 <pub-id pub-id-type="doi">10.1136/gut.2007.146357</pub-id><pub-id pub-id-type="pmid">18566104</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1136/gut.2007.146357">https://doi.org/10.1136/gut.2007.146357</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Henriksen, M.</string-name>
              <string-name>Jahnsen, J.</string-name>
              <string-name>Lygren, I.</string-name>
              <string-name>Stray, N.</string-name>
              <string-name>Sauar, J.</string-name>
              <string-name>Vatn, M.H.</string-name>
            </person-group>
            <year>2008</year>
            <article-title>C-reactive Protein: A Predictive Factor and Marker of Inflammation in Inflammatory Bowel Disease</article-title>
            <source>Results from a Prospective Population-Based Study. Gut</source>
            <volume>57</volume>
            <pub-id pub-id-type="doi">10.1136/gut.2007.146357</pub-id>
            <pub-id pub-id-type="pmid">18566104</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B7">
        <label>7.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Tibble, J.A., Sigthorsson, G., Foster, R., Forgacs, I. and Bjarnason, I. (2002) Use of Surrogate Markers of Inflammation and Rome Criteria to Distinguish Organic from Nonorganic Intestinal Disease. <italic>Gastroenterology</italic>, 123, 450-460. https://doi.org/10.1053/gast.2002.34755 <pub-id pub-id-type="doi">10.1053/gast.2002.34755</pub-id><pub-id pub-id-type="pmid">12145798</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/gast.2002.34755">https://doi.org/10.1053/gast.2002.34755</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Tibble, J.A.</string-name>
              <string-name>Sigthorsson, G.</string-name>
              <string-name>Foster, R.</string-name>
              <string-name>Forgacs, I.</string-name>
              <string-name>Bjarnason, I.</string-name>
            </person-group>
            <year>2002</year>
            <article-title>Use of Surrogate Markers of Inflammation and Rome Criteria to Distinguish Organic from Nonorganic Intestinal Disease</article-title>
            <source>Gastroenterology</source>
            <volume>123</volume>
            <pub-id pub-id-type="doi">10.1053/gast.2002.34755</pub-id>
            <pub-id pub-id-type="pmid">12145798</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B8">
        <label>8.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Daperno, M., D’Haens, G., Van Assche, G., Baert, F., Bulois, P., Maunoury, V., <italic>et al</italic>. (2004) Development and Validation of a New, Simplified Endoscopic Activity Score for Crohn’s Disease: The SES-CD. <italic>Gastrointestinal Endoscopy</italic>, 60, 505-512. https://doi.org/10.1016/s0016-5107(04)01878-4 <pub-id pub-id-type="doi">10.1016/s0016-5107(04)01878-4</pub-id><pub-id pub-id-type="pmid">15472670</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/s0016-5107(04)01878-4">https://doi.org/10.1016/s0016-5107(04)01878-4</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Daperno, M.</string-name>
              <string-name>Haens, G.</string-name>
              <string-name>Assche, G.</string-name>
              <string-name>Baert, F.</string-name>
              <string-name>Bulois, P.</string-name>
              <string-name>Maunoury, V.</string-name>
              <string-name>New, S</string-name>
            </person-group>
            <year>2004</year>
            <article-title>Development and Validation of a New, Simplified Endoscopic Activity Score for Crohn’s Disease: The SES-CD</article-title>
            <source>Gastrointestinal Endoscopy</source>
            <volume>5107</volume>
            <issue>04</issue>
            <pub-id pub-id-type="doi">10.1016/s0016-5107(04)01878-4</pub-id>
            <pub-id pub-id-type="pmid">15472670</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B9">
        <label>9.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Schroeder, K.W., Tremaine, W.J. and Ilstrup, D.M. (1987) Coated Oral 5-Aminosalicylic Acid Therapy for Mildly to Moderately Active Ulcerative Colitis. <italic>New England Journal of Medicine</italic>, 317, 1625-1629. https://doi.org/10.1056/nejm198712243172603 <pub-id pub-id-type="doi">10.1056/nejm198712243172603</pub-id><pub-id pub-id-type="pmid">3317057</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1056/nejm198712243172603">https://doi.org/10.1056/nejm198712243172603</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Schroeder, K.W.</string-name>
              <string-name>Tremaine, W.J.</string-name>
              <string-name>Ilstrup, D.M.</string-name>
            </person-group>
            <year>1987</year>
            <article-title>Coated Oral 5-Aminosalicylic Acid Therapy for Mildly to Moderately Active Ulcerative Colitis</article-title>
            <source>New England Journal of Medicine</source>
            <volume>317</volume>
            <pub-id pub-id-type="doi">10.1056/nejm198712243172603</pub-id>
            <pub-id pub-id-type="pmid">3317057</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B10">
        <label>10.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Sherwood, R. and Walsham, N. (2016) Fecal Calprotectin in Inflammatory Bowel Disease. <italic>Clinical</italic><italic>and</italic><italic>Experimental</italic><italic>Gastroenterology</italic>, 9, 21-29. https://doi.org/10.2147/ceg.s51902 <pub-id pub-id-type="doi">10.2147/ceg.s51902</pub-id><pub-id pub-id-type="pmid">26869808</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.2147/ceg.s51902">https://doi.org/10.2147/ceg.s51902</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Sherwood, R.</string-name>
              <string-name>Walsham, N.</string-name>
            </person-group>
            <year>2016</year>
            <article-title>Fecal Calprotectin in Inflammatory Bowel Disease</article-title>
            <source>Clinical and Experimental Gastroenterology</source>
            <volume>9</volume>
            <pub-id pub-id-type="doi">10.2147/ceg.s51902</pub-id>
            <pub-id pub-id-type="pmid">26869808</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B11">
        <label>11.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Sipponen, T., Savilahti, E., Kolho, K., Nuutinen, H., Turunen, U. and Färkkilä, M. (2008) Crohnʼs Disease Activity Assessed by Fecal Calprotectin and Lactoferrin: Correlation with Crohnʼs Disease Activity Index and Endoscopic Findings. <italic>I</italic><italic>nflammatory</italic><italic>Bowel</italic><italic>Diseases</italic>, 14, 40-46. https://doi.org/10.1002/ibd.20312 <pub-id pub-id-type="doi">10.1002/ibd.20312</pub-id><pub-id pub-id-type="pmid">18022866</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/ibd.20312">https://doi.org/10.1002/ibd.20312</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Sipponen, T.</string-name>
              <string-name>Savilahti, E.</string-name>
              <string-name>Kolho, K.</string-name>
              <string-name>Nuutinen, H.</string-name>
              <string-name>Turunen, U.</string-name>
            </person-group>
            <year>2008</year>
            <article-title>Crohnʼs Disease Activity Assessed by Fecal Calprotectin and Lactoferrin: Correlation with Crohnʼs Disease Activity Index and Endoscopic Findings</article-title>
            <source>Inflammatory Bowel Diseases</source>
            <volume>14</volume>
            <pub-id pub-id-type="doi">10.1002/ibd.20312</pub-id>
            <pub-id pub-id-type="pmid">18022866</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B12">
        <label>12.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Schoepfer, A.M., Beglinger, C., Straumann, A., Safroneeva, E., Romero, Y., Armstrong, D., <italic>et al</italic>. (2010) Fecal Calprotectin Correlates More Closely with Endoscopic Activity than CRP in Ulcerative Colitis. <italic>Gut</italic>, 59, 151-156.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Schoepfer, A.M.</string-name>
              <string-name>Beglinger, C.</string-name>
              <string-name>Straumann, A.</string-name>
              <string-name>Safroneeva, E.</string-name>
              <string-name>Romero, Y.</string-name>
              <string-name>Armstrong, D.</string-name>
            </person-group>
            <year>2010</year>
            <article-title>Fecal Calprotectin Correlates More Closely with Endoscopic Activity than CRP in Ulcerative Colitis</article-title>
            <source>Gut</source>
            <volume>59</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B13">
        <label>13.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Mosli, M.H., Zou, G., Garg, S.K., Feagan, S.G., MacDonald, J.K., Chande, N., <italic>et al</italic>. (2015) C-Reactive Protein, Fecal Calprotectin, and Stool Lactoferrin for Detection of Endoscopic Activity in Symptomatic Inflammatory Bowel Disease Patients: A Systematic Review and Meta-Analysis. <italic>American</italic><italic>Journal</italic><italic>of</italic><italic>Gastroenterology</italic>, 110, 802-819. https://doi.org/10.1038/ajg.2015.120 <pub-id pub-id-type="doi">10.1038/ajg.2015.120</pub-id><pub-id pub-id-type="pmid">25964225</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1038/ajg.2015.120">https://doi.org/10.1038/ajg.2015.120</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Mosli, M.H.</string-name>
              <string-name>Zou, G.</string-name>
              <string-name>Garg, S.K.</string-name>
              <string-name>Feagan, S.G.</string-name>
              <string-name>MacDonald, J.K.</string-name>
              <string-name>Chande, N.</string-name>
              <string-name>Protein, F</string-name>
            </person-group>
            <year>2015</year>
            <article-title>C-Reactive Protein, Fecal Calprotectin, and Stool Lactoferrin for Detection of Endoscopic Activity in Symptomatic Inflammatory Bowel Disease Patients: A Systematic Review and Meta-Analysis</article-title>
            <source>American Journal of Gastroenterology</source>
            <volume>110</volume>
            <pub-id pub-id-type="doi">10.1038/ajg.2015.120</pub-id>
            <pub-id pub-id-type="pmid">25964225</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B14">
        <label>14.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Lin, J., Chen, J., Zuo, J., Yu, A., Xiao, Z., Deng, F., <italic>et al</italic>. (2014) Meta-Analysis: Fecal Calprotectin for Assessment of IBD Activity. <italic>Inflammatory</italic><italic>Bowel</italic><italic>Diseases</italic>, 20, 1407-1415. https://doi.org/10.1097/mib.0000000000000057 <pub-id pub-id-type="doi">10.1097/mib.0000000000000057</pub-id><pub-id pub-id-type="pmid">24983982</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1097/mib.0000000000000057">https://doi.org/10.1097/mib.0000000000000057</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Lin, J.</string-name>
              <string-name>Chen, J.</string-name>
              <string-name>Zuo, J.</string-name>
              <string-name>Yu, A.</string-name>
              <string-name>Xiao, Z.</string-name>
              <string-name>Deng, F.</string-name>
            </person-group>
            <year>2014</year>
            <article-title>Meta-Analysis: Fecal Calprotectin for Assessment of IBD Activity</article-title>
            <source>Inflammatory Bowel Diseases</source>
            <volume>20</volume>
            <pub-id pub-id-type="doi">10.1097/mib.0000000000000057</pub-id>
            <pub-id pub-id-type="pmid">24983982</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B15">
        <label>15.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Gisbert, J.P. and McNicholl, A.G. (2009) Questions and Answers on the Role of Faecal Calprotectin as a Biological Marker in Inflammatory Bowel Disease. <italic>Digestive and Liver Disease</italic>, 41, 56-66. https://doi.org/10.1016/j.dld.2008.05.008 <pub-id pub-id-type="doi">10.1016/j.dld.2008.05.008</pub-id><pub-id pub-id-type="pmid">18602356</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/j.dld.2008.05.008">https://doi.org/10.1016/j.dld.2008.05.008</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Gisbert, J.P.</string-name>
              <string-name>McNicholl, A.G.</string-name>
            </person-group>
            <year>2009</year>
            <article-title>Questions and Answers on the Role of Faecal Calprotectin as a Biological Marker in Inflammatory Bowel Disease</article-title>
            <source>Digestive and Liver Disease</source>
            <volume>41</volume>
            <pub-id pub-id-type="doi">10.1016/j.dld.2008.05.008</pub-id>
            <pub-id pub-id-type="pmid">18602356</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B16">
        <label>16.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">van Rheenen, P.F., Van de Vijver, E. and Fidler, V. (2010) Faecal Calprotectin for Screening of Patients with Suspected Inflammatory Bowel Disease: Diagnostic Meta-analysis. <italic>BMJ</italic>, 341, c3369-c3369. https://doi.org/10.1136/bmj.c3369 <pub-id pub-id-type="doi">10.1136/bmj.c3369</pub-id><pub-id pub-id-type="pmid">20634346</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1136/bmj.c3369">https://doi.org/10.1136/bmj.c3369</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Rheenen, P.F.</string-name>
              <string-name>Vijver, E.</string-name>
              <string-name>Fidler, V.</string-name>
            </person-group>
            <year>2010</year>
            <article-title>Faecal Calprotectin for Screening of Patients with Suspected Inflammatory Bowel Disease: Diagnostic Meta-analysis</article-title>
            <source>BMJ</source>
            <volume>341</volume>
            <pub-id pub-id-type="doi">10.1136/bmj.c3369</pub-id>
            <pub-id pub-id-type="pmid">20634346</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B17">
        <label>17.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Lasson, A., Simrén, M., Stotzer, P.O., Öhman, L. and Strid, H. (2015) Fecal Calprotectin Predicts Relapse in Ulcerative Colitis. <italic>Inflammatory Bowel Disease</italic>, 21, 2341-2347.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Lasson, A.</string-name>
              <string-name>Stotzer, P.O.</string-name>
              <string-name>Strid, H.</string-name>
            </person-group>
            <year>2015</year>
            <article-title>Fecal Calprotectin Predicts Relapse in Ulcerative Colitis</article-title>
            <source>Inflammatory Bowel Disease</source>
            <volume>21</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B18">
        <label>18.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Bryant, R.V., Burger, D.C., Delo, J., Walsh, A.J., Thomas, S., von Herbay, A., <italic>et al</italic>. (2016) Beyond Endoscopic Mucosal Healing in Inflammatory Bowel Disease. <italic>Nature Reviews Gastroenterology &amp; Hepatology</italic>, 13, 567-578.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Bryant, R.V.</string-name>
              <string-name>Burger, D.C.</string-name>
              <string-name>Delo, J.</string-name>
              <string-name>Walsh, A.J.</string-name>
              <string-name>Thomas, S.</string-name>
              <string-name>Herbay, A.</string-name>
            </person-group>
            <year>2016</year>
            <article-title>Beyond Endoscopic Mucosal Healing in Inflammatory Bowel Disease</article-title>
            <source>Nature Reviews Gastroenterology &amp; Hepatology</source>
            <volume>13</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B19">
        <label>19.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Sands, B.E. (2015) Biomarkers of Inflammation in Inflammatory Bowel Disease. <italic>Gastroenterology</italic>, 149, 1275-1285.e2. https://doi.org/10.1053/j.gastro.2015.07.003 <pub-id pub-id-type="doi">10.1053/j.gastro.2015.07.003</pub-id><pub-id pub-id-type="pmid">26166315</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/j.gastro.2015.07.003">https://doi.org/10.1053/j.gastro.2015.07.003</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Sands, B.E.</string-name>
            </person-group>
            <year>2015</year>
            <article-title>Biomarkers of Inflammation in Inflammatory Bowel Disease</article-title>
            <source>Gastroenterology</source>
            <volume>149</volume>
            <pub-id pub-id-type="doi">10.1053/j.gastro.2015.07.003</pub-id>
            <pub-id pub-id-type="pmid">26166315</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B20">
        <label>20.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Lewis, J.D. (2011) The Utility of Biomarkers in the Diagnosis and Therapy of Inflammatory Bowel Disease. <italic>Gastroenterology</italic>, 140, 1817-1826.e2. https://doi.org/10.1053/j.gastro.2010.11.058 <pub-id pub-id-type="doi">10.1053/j.gastro.2010.11.058</pub-id><pub-id pub-id-type="pmid">21530748</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/j.gastro.2010.11.058">https://doi.org/10.1053/j.gastro.2010.11.058</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Lewis, J.D.</string-name>
            </person-group>
            <year>2011</year>
            <article-title>The Utility of Biomarkers in the Diagnosis and Therapy of Inflammatory Bowel Disease</article-title>
            <source>Gastroenterology</source>
            <volume>140</volume>
            <pub-id pub-id-type="doi">10.1053/j.gastro.2010.11.058</pub-id>
            <pub-id pub-id-type="pmid">21530748</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B21">
        <label>21.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Burri, E. and Beglinger, C. (2013) The Use of Fecal Calprotectin as a Biomarker in Gastrointestinal Disease. <italic>E</italic><italic>xpert</italic><italic>Review</italic><italic>of</italic><italic>Gastroenterology</italic><italic>&amp;</italic><italic>Hepatology</italic>, 8, 197-210. https://doi.org/10.1586/17474124.2014.869476 <pub-id pub-id-type="doi">10.1586/17474124.2014.869476</pub-id><pub-id pub-id-type="pmid">24345070</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1586/17474124.2014.869476">https://doi.org/10.1586/17474124.2014.869476</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Burri, E.</string-name>
              <string-name>Beglinger, C.</string-name>
            </person-group>
            <year>2013</year>
            <article-title>The Use of Fecal Calprotectin as a Biomarker in Gastrointestinal Disease</article-title>
            <source>Expert Review of Gastroenterology &amp; Hepatology</source>
            <volume>8</volume>
            <pub-id pub-id-type="doi">10.1586/17474124.2014.869476</pub-id>
            <pub-id pub-id-type="pmid">24345070</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B22">
        <label>22.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Mosli, M.H., Feagan, B.G., Zou, G., Sandborn, W.J., D’Haens, G., Khanna, R., <italic>et al</italic>. (2015) Reproducibility of Fecal Calprotectin Measurements. <italic>Inflammatory Bowel Disease</italic>, 21, 2211-2217.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Mosli, M.H.</string-name>
              <string-name>Feagan, B.G.</string-name>
              <string-name>Zou, G.</string-name>
              <string-name>Sandborn, W.J.</string-name>
              <string-name>Haens, G.</string-name>
              <string-name>Khanna, R.</string-name>
            </person-group>
            <year>2015</year>
            <article-title>Reproducibility of Fecal Calprotectin Measurements</article-title>
            <source>Inflammatory Bowel Disease</source>
            <volume>21</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B23">
        <label>23.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Lasson, A., Öhman, L., Stotzer, P.O., Simrén, M. and Strid, H. (2013) Monitoring Ulcerative Colitis with Fecal Calprotectin. <italic>Scandinavian Journal of Gastroenterology</italic>, 48, 1133-1138.</mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Lasson, A.</string-name>
              <string-name>Stotzer, P.O.</string-name>
              <string-name>Strid, H.</string-name>
            </person-group>
            <year>2013</year>
            <article-title>Monitoring Ulcerative Colitis with Fecal Calprotectin</article-title>
            <source>Scandinavian Journal of Gastroenterology</source>
            <volume>48</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B24">
        <label>24.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Schoepfer, A.M., Trummler, M., Seeholzer, P., Seibold-Schmid, B. and Seibold, F. (2008) Discriminating IBD from IBS: Comparison of the Test Performance of Fecal Markers, Blood Leukocytes, CRP, and IBD Antibodies. <italic>Inflammatory</italic><italic>Bowel</italic><italic>Diseases</italic>, 14, 32-39. https://doi.org/10.1002/ibd.20275 <pub-id pub-id-type="doi">10.1002/ibd.20275</pub-id><pub-id pub-id-type="pmid">17924558</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/ibd.20275">https://doi.org/10.1002/ibd.20275</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Schoepfer, A.M.</string-name>
              <string-name>Trummler, M.</string-name>
              <string-name>Seeholzer, P.</string-name>
              <string-name>Seibold-Schmid, B.</string-name>
              <string-name>Seibold, F.</string-name>
              <string-name>Markers, B</string-name>
              <string-name>Leukocytes, C</string-name>
            </person-group>
            <year>2008</year>
            <article-title>Discriminating IBD from IBS: Comparison of the Test Performance of Fecal Markers, Blood Leukocytes, CRP, and IBD Antibodies</article-title>
            <source>Inflammatory Bowel Diseases</source>
            <volume>14</volume>
            <pub-id pub-id-type="doi">10.1002/ibd.20275</pub-id>
            <pub-id pub-id-type="pmid">17924558</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B25">
        <label>25.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Kostas, A., Siakavellas, S.I., Kosmidis, C., Takou, A., Nikou, J., Maropoulos, G., <italic>et</italic><italic>al</italic>. (2015) Fecal Calprotectin in Inflammatory Bowel Disease. <italic>Annals of Gastroenterology</italic>, 28, 1-8.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Kostas, A.</string-name>
              <string-name>Siakavellas, S.I.</string-name>
              <string-name>Kosmidis, C.</string-name>
              <string-name>Takou, A.</string-name>
              <string-name>Nikou, J.</string-name>
              <string-name>Maropoulos, G.</string-name>
            </person-group>
            <year>2015</year>
            <article-title>Fecal Calprotectin in Inflammatory Bowel Disease</article-title>
            <source>Annals of Gastroenterology</source>
            <volume>28</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B26">
        <label>26.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Peyrin-Biroulet, L., Loftus, E.V., Colombel, J. and Sandborn, W.J. (2010) The Natural History of Adult Crohn’s Disease in Population-Based Cohorts. <italic>American Journal of Gastroenterology</italic>, 105, 289-297. https://doi.org/10.1038/ajg.2009.579 <pub-id pub-id-type="doi">10.1038/ajg.2009.579</pub-id><pub-id pub-id-type="pmid">19861953</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1038/ajg.2009.579">https://doi.org/10.1038/ajg.2009.579</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Peyrin-Biroulet, L.</string-name>
              <string-name>Loftus, E.V.</string-name>
              <string-name>Colombel, J.</string-name>
              <string-name>Sandborn, W.J.</string-name>
            </person-group>
            <year>2010</year>
            <article-title>The Natural History of Adult Crohn’s Disease in Population-Based Cohorts</article-title>
            <source>American Journal of Gastroenterology</source>
            <volume>105</volume>
            <pub-id pub-id-type="doi">10.1038/ajg.2009.579</pub-id>
            <pub-id pub-id-type="pmid">19861953</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B27">
        <label>27.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">DʼHaens, G., Ferrante, M., Vermeire, S., Baert, F., Noman, M., Moortgat, L., <italic>et al</italic>. (2012) Fecal Calprotectin Is a Surrogate Marker for Endoscopic Lesions in Inflammatory Bowel Disease. <italic>Inflammatory</italic><italic>Bowel</italic><italic>Diseases</italic>, 18, 2218-2224. https://doi.org/10.1002/ibd.22917 <pub-id pub-id-type="doi">10.1002/ibd.22917</pub-id><pub-id pub-id-type="pmid">22344983</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/ibd.22917">https://doi.org/10.1002/ibd.22917</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Haens, G.</string-name>
              <string-name>Ferrante, M.</string-name>
              <string-name>Vermeire, S.</string-name>
              <string-name>Baert, F.</string-name>
              <string-name>Noman, M.</string-name>
              <string-name>Moortgat, L.</string-name>
            </person-group>
            <year>2012</year>
            <article-title>Fecal Calprotectin Is a Surrogate Marker for Endoscopic Lesions in Inflammatory Bowel Disease</article-title>
            <source>Inflammatory Bowel Diseases</source>
            <volume>18</volume>
            <pub-id pub-id-type="doi">10.1002/ibd.22917</pub-id>
            <pub-id pub-id-type="pmid">22344983</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B28">
        <label>28.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Kennedy, N.A., Jones, G.R., Lamb, C.A., Appleby, R., Arnott, I., Beattie, R.M., <italic>et al</italic>. (2019) British Society of Gastroenterology Guidance for IBD Management. <italic>Gut</italic>, 68, S1-S106.</mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Kennedy, N.A.</string-name>
              <string-name>Jones, G.R.</string-name>
              <string-name>Lamb, C.A.</string-name>
              <string-name>Appleby, R.</string-name>
              <string-name>Arnott, I.</string-name>
              <string-name>Beattie, R.M.</string-name>
            </person-group>
            <year>2019</year>
            <article-title>British Society of Gastroenterology Guidance for IBD Management</article-title>
            <source>Gut</source>
            <volume>68</volume>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B29">
        <label>29.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Turner, D., Ricciuto, A., Lewis, A., D’Amico, F., Dhaliwal, J., Griffiths, A.M., <italic>et al</italic>. (2021) STRIDE-II: An Update on the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) Initiative of the International Organization for the Study of IBD (IOIBD): Determining Therapeutic Goals for Treat-to-Target Strategies in IBD. <italic>Gastroenterology</italic>, 160, 1570-1583. https://doi.org/10.1053/j.gastro.2020.12.031 <pub-id pub-id-type="doi">10.1053/j.gastro.2020.12.031</pub-id><pub-id pub-id-type="pmid">33359090</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/j.gastro.2020.12.031">https://doi.org/10.1053/j.gastro.2020.12.031</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Turner, D.</string-name>
              <string-name>Ricciuto, A.</string-name>
              <string-name>Lewis, A.</string-name>
              <string-name>Amico, F.</string-name>
              <string-name>Dhaliwal, J.</string-name>
              <string-name>Griffiths, A.M.</string-name>
            </person-group>
            <year>2021</year>
            <article-title>STRIDE-II: An Update on the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) Initiative of the International Organization for the Study of IBD (IOIBD): Determining Therapeutic Goals for Treat-to-Target Strategies in IBD</article-title>
            <source>Gastroenterology</source>
            <volume>160</volume>
            <pub-id pub-id-type="doi">10.1053/j.gastro.2020.12.031</pub-id>
            <pub-id pub-id-type="pmid">33359090</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B30">
        <label>30.</label>
        <citation-alternatives>
          <mixed-citation publication-type="journal">Ungaro, R., Mehandru, S., Allen, P.B., Peyrin-Biroulet, L. and Colombel, J. (2017) Ulcerative Colitis. <italic>The</italic><italic>Lancet</italic>, 389, 1756-1770. https://doi.org/10.1016/s0140-6736(16)32126-2 <pub-id pub-id-type="doi">10.1016/s0140-6736(16)32126-2</pub-id><pub-id pub-id-type="pmid">27914657</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/s0140-6736(16)32126-2">https://doi.org/10.1016/s0140-6736(16)32126-2</ext-link></mixed-citation>
          <element-citation publication-type="journal">
            <person-group person-group-type="author">
              <string-name>Ungaro, R.</string-name>
              <string-name>Mehandru, S.</string-name>
              <string-name>Allen, P.B.</string-name>
              <string-name>Peyrin-Biroulet, L.</string-name>
              <string-name>Colombel, J.</string-name>
            </person-group>
            <year>2017</year>
            <article-title>Ulcerative Colitis</article-title>
            <source>The Lancet</source>
            <volume>6736</volume>
            <issue>16</issue>
            <pub-id pub-id-type="doi">10.1016/s0140-6736(16)32126-2</pub-id>
            <pub-id pub-id-type="pmid">27914657</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B31">
        <label>31.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Singh, S., Ananthakrishnan, A.N., Nguyen, N.H., Cohen, B.L., Velayos, F.S., Weiss, J.M., <italic>et al</italic>. (2023) AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Ulcerative Colitis. <italic>Gastroenterology</italic>, 164, 344-372. https://doi.org/10.1053/j.gastro.2022.12.007 <pub-id pub-id-type="doi">10.1053/j.gastro.2022.12.007</pub-id><pub-id pub-id-type="pmid">36822736</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1053/j.gastro.2022.12.007">https://doi.org/10.1053/j.gastro.2022.12.007</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Singh, S.</string-name>
              <string-name>Ananthakrishnan, A.N.</string-name>
              <string-name>Nguyen, N.H.</string-name>
              <string-name>Cohen, B.L.</string-name>
              <string-name>Velayos, F.S.</string-name>
              <string-name>Weiss, J.M.</string-name>
            </person-group>
            <year>2023</year>
            <article-title>AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Ulcerative Colitis</article-title>
            <source>Gastroenterology</source>
            <volume>164</volume>
            <pub-id pub-id-type="doi">10.1053/j.gastro.2022.12.007</pub-id>
            <pub-id pub-id-type="pmid">36822736</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
      <ref id="B32">
        <label>32.</label>
        <citation-alternatives>
          <mixed-citation publication-type="other">Clough, J., Colwill, M., Poullis, A., Pollok, R., Patel, K. and Honap, S. (2024) Biomarkers in Inflammatory Bowel Disease: A Practical Guide. <italic>Therapeutic</italic><italic>Advances</italic><italic>in</italic><italic>Gastroenterology</italic>, 17. https://doi.org/10.1177/17562848241251600 <pub-id pub-id-type="doi">10.1177/17562848241251600</pub-id><pub-id pub-id-type="pmid">38737913</pub-id><ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1177/17562848241251600">https://doi.org/10.1177/17562848241251600</ext-link></mixed-citation>
          <element-citation publication-type="other">
            <person-group person-group-type="author">
              <string-name>Clough, J.</string-name>
              <string-name>Colwill, M.</string-name>
              <string-name>Poullis, A.</string-name>
              <string-name>Pollok, R.</string-name>
              <string-name>Patel, K.</string-name>
              <string-name>Honap, S.</string-name>
            </person-group>
            <year>2024</year>
            <article-title>Biomarkers in Inflammatory Bowel Disease: A Practical Guide</article-title>
            <source>Therapeutic Advances in Gastroenterology</source>
            <volume>17</volume>
            <pub-id pub-id-type="doi">10.1177/17562848241251600</pub-id>
            <pub-id pub-id-type="pmid">38737913</pub-id>
          </element-citation>
        </citation-alternatives>
      </ref>
    </ref-list>
  </back>
</article>