As an indispensable auxiliary examination method in modern clinical medicine, biochemical tests can directly reflect human organ function, substance metabolism and homeostasis of internal environment, and run through the whole process of disease diagnosis, treatment and prognosis evaluation [[1]]. Departments admit patients with different primary diseases, which involve different target organs and metabolic disorders, leading to differentiated manifestations of various biochemical indicators.

Diseases of the hepatobiliary system usually cause abnormal elevation of transaminase and bilirubin [[2]]. Cardiovascular and cerebrovascular diseases are often accompanied by disorders of myocardial enzymes, blood lipids and electrolytes [[3]]. Infectious diseases result in increased physical consumption and activated inflammation, which indirectly affect the levels of protein-related indicators [[4]]. Surgical trauma may damage skeletal muscles and cause fluctuations of creatine kinase. At present, most clinical studies focus on biochemical indicators of a single disease or a single department, while horizontal comparative studies covering multiple departments across the hospital are relatively insufficient, making it difficult to form a unified interpretation framework for test results [[5]].

Based on real inpatient data from our hospital, this study conducted a statistical analysis on full-set biochemical test results of patients from seven clinical departments, summarized the characteristics of biochemical indicators in each department, and identified test items with department-specific features. The findings are expected to help clinicians interpret test reports more accurately, and provide basic data for optimizing laboratory reference ranges and establishing hospital-wide disease screening systems.

This study conducted a horizontal comparison of biochemical indicators among 597 inpatients from seven mainstream clinical departments after excluding cases from gastroenterology, anorectal surgery and pediatric surgery. The results verified that biochemical indicators differed remarkably across departments, and the variations were highly correlated with pathological changes of corresponding diseases. The statistically significant inter-departmental differences of all indicators also have practical clinical significance.

Patients in the Department of Hepatobiliary, Gland and Vascular Surgery were mainly diagnosed with liver, biliary tract and pancreatic diseases, whose core pathological manifestations included hepatocellular injury and biliary obstruction. ALT and AST are mainly distributed in the cytoplasm and mitochondria of hepatocytes, and they are released into blood in large quantities when hepatocytes are damaged. Impaired metabolism and excretion of bilirubin lead to elevated total bilirubin and direct bilirubin. ALP and γ-GT are characteristic indicators of biliary tract injury, which explains the comprehensive elevation of the above indicators in this group, consistent with typical laboratory manifestations of hepatobiliary diseases [[6]].

Elevated CK levels were observed in patients from the Department of Neurosurgery & Thoracic Surgery and neurology departments. CK is mainly distributed in skeletal muscle and cardiac muscle tissues. Surgical trauma causes mechanical damage to skeletal muscle in patients receiving operations in neurosurgery and thoracic surgery departments. Cerebrovascular diseases and myopathies, common in neurology departments, also result in myocyte damage and subsequent CK release [[7]]. Although the underlying causes differ, the laboratory performances are similar in these two groups.

Albumin levels were obviously decreased in patients from the Department of Infectious Diseases. Infection and inflammatory reactions induce hypermetabolism and increased protein consumption. Meanwhile, inflammatory factors inhibit hepatic protein synthesis, leading to reduced serum albumin, which serves as an important laboratory marker of poor nutritional status in infected patients [[8]]. Serum calcium levels were relatively high in the Department of Cardiology and Department of Neurology II, which may be associated with bone metabolism disorders and medication use among elderly patients with cardiovascular diseases.

The Department of Gastroenterology had the highest LDH level. LDH is widely distributed in human tissues. Tissue hypoxia, mucosal damage and systemic stress can all cause its elevation. Digestive tract hemorrhage and severe gastrointestinal diseases are common in gastroenterology patients, which easily trigger systemic stress and tissue injury, thus increasing LDH levels.

No significant inter-departmental differences were found in blood glucose, triglyceride and low-density lipoprotein cholesterol. These indicators are affected by multiple individual factors including diet, living habits, chronic underlying diseases and temporary medication use. Individual variations prevail over group differences among departments, so these indicators present no department-specific characteristics.

Combined with the research results, clinicians should not merely judge test results by general reference ranges. Comprehensive interpretation combining patients’ affiliated departments and underlying diseases is required. For instance, isolated elevated transaminase in patients from hepatobiliary departments is mostly attributed to primary hepatobiliary diseases, while the same change in postoperative surgical patients is likely caused by surgical stress or transient drug effects, avoiding overdiagnosis. The indicator characteristics summarized in this study can also be applied as references for preliminary hospital-wide disease screening to improve the efficiency of initial assessment for outpatient and inpatient cases.

Multiple biochemical indicators of inpatients from seven clinical departments in the general hospital have significant inter-departmental differences, which are determined by organ damage, metabolic status and treatment regimens of corresponding diseases. Hepatobiliary-related indicators are characteristically elevated in patients of the Department of Hepatobiliary, Gland and Vascular Surgery. CK increases obviously in patients receiving neurological and surgical treatment, and albumin generally declines in patients with infectious diseases. The above indicators can be used as important auxiliary evidence for diagnosis in corresponding departments. Clinicians should interpret biochemical test results individually with consideration of departmental and disease background, so as to further improve the clinical application value of biochemical tests.

First, this is a single-center retrospective study with data only collected from our hospital, which limits the extrapolation of conclusions to other medical institutions. Second, this study only conducted overall inter-group comparison, without stratified analysis and adjustment for confounding factors such as age, gender, disease severity, treatment regimens, combined medication and surgical history, so it cannot refine the indicator characteristics of different subgroups. Third, several departments have relatively small sample sizes (e.g. Department of Neurosurgery & Thoracic Surgery), which may slightly affect the stability of statistical results. This study did not perform post-hoc multiple comparisons, so it cannot accurately identify pairwise inter-departmental differences. Further multi-center studies with expanded sample size, stratified analysis and multiple comparison analysis will be carried out to optimize the research conclusions in the future.

We sincerely appreciate the strong support from all medical staff in the Department of Clinical Laboratory and various clinical departments of our hospital.

*Co-first authors.