Nephrotic syndrome (NS) is a frequent glomerulopathy in pediatrics, characterized by a leakage of blood proteins to the urine through damaged glomeruli [1] . The nephrotic syndrome of the child is defined biologically by the association of a 24-hour proteinuria greater than 50 mg/kg, a hypo-protidemia less than 60 g/L and a hypo-albuminemia less than 30 g/L. It is said to be impure when it is accompanied by arterial hypertension (HYPERTENSION) and/or renal insufficiency and/or microscopic hematuria (Hu) and/or if proteinuria is not selective. Otherwise, the SN is said to be pure [2] - [6] . It has an estimated hospital frequency of 0.26% in Côte d’Ivoire, 0.27% in Senegal and 0.8% in Congo Brazzaville [3] [7] [8] .

The nephrotic syndrome is one of the most frequent glomerular nephropathies in children aged 2 to 12 years, often after an infectious or allergic trigger [4] [9] - [11] . The annual global incidence has been estimated at between 1 and 4.7 cases/100,000 children [1] [9] [12] - [14] . Data on nephrotic syndrome are limited in sub-Saharan Africa.sub-Saharan Africa. It is predominant among male patients with a sex ratio of 1.7 to 2 [2] [7] [9] - [11] [15] .

Nephrotic syndrome is often associated with multiple relapses, with a psychological and academic impact and presents challenges in terms of diagnosis and management [16] . Its pathophysiology remains imperfectly known. Recent studies have identified genetic mutations responsible for hereditary forms of SN often progressing to renal insufficiency and progress is being made in understanding the pathophysiology and mechanisms of glomerular permeability to plasma proteins [15] [16] . The response to treatment varies according to the histological classification with steroid sensitivity observed in more than 90% of children with minimal lesion disease (MCD) compared to 25 to 50% of those with focal segmental glomerulosclerosis (FSGS) [1] [17] - [19] . Indications for renal biopsy are limited to unusual presentations or cases of non-response to corticosteroid therapy. The nephrotic syndrome of the child therefore presents itself in 3 clinical forms according to the response to the initial corticosteroid therapy: the corticosensitive nephrotic syndrome (CNS), the corticodependent nephrotic syndrome (SNCD) and the corticoresistant nephrotic syndrome (CRNS) [9] [19] [20] . There are also primary or idiopathic nephrotic syndrome (without initial cause), secondary nephrotic syndrome following an extra-renal cause and congenital nephrotic syndrome [12] [14] [21] .

The nephrophrotic syndrome can be defined as “impure” when it is accompanied by arterial hypertension and/or renal insufficiency and/or microscopic hematuria and/or if proteinuria is not selective. Otherwise, it is defined as “pure” [2] - [6] . Impure NS is less likely to be primary and respond less easily to corticosteroid therapy. Complications of NS and its treatment can put the vital prognosis of some children at risk. The aim of this study was to study the diagnosis and evolution of SN in the context of limited resources in a pediatric setting at the National Hospital of Zinder.

This work reports the characteristics of nephrotic syndrome in a hospital setting. The limitations of this study were above all the lack of financial means by the parents for carrying out etiological examinations, including the PBR, even if indicated.

During the study period, out of a total of 3758 patients, 26 cases of nephrotic syndrome in children were recorded, representing a hospital prevalence of 0.69%.

Table 1 presents the socio-demographic characteristics of the patients. The age group of 5 to 10 years was the most represented with 57.69% (n = 15) and the average age was 8 ± 2.99 years with extremes of 5 and 14 years. A male predominance was observed, with a sex ratio of 1.3. Children from rural areas accounted for 76.92% (n = 20) of the cases.

The history of angina and edema were found in 11.54% and 7.7%, respectively. The consultation period was greater than or equal to 14 days in 61.54% (n = 16) of the cases and statistically significant with the reason for consultation (OR = 10; CI [0.87 - 114.75]; p = 0.04). Anasarca was the main reason for consultation in 84.62% (n = 22) of cases and was the main sign found on physical examination followed by mucocutaneous pallor in 84.62% and 53.84% respectively. HYPERTENSION was found in 23.07% (n = 6) of the cases ( Table 2 ).

Hyperleukocytosis was present in 30.23% (n = 8) of patients and anemia in 84.62% (n = 22) of cases. Nine (9) children had high azotemia, i.e., 34.60%, and serum creatinine was high in three patients, i.e., 11.54%. The 24-hour proteinuria was greater than 50 mg/kg/day in all patients. It was between 50 and 100 mg/kg/day in 65% of cases with an average of 82.78 mg/kg/d (extremes ranging from 54 to 244 mg/kg/d). There was no significant correlation between the 24-hour proteinuria and the consultation time (OR = 1.46; p = 0.69). The average protidemia was 44.85 g/L with extremes of 3.85 and 58.70 g/L. The average albuminemia was 18.78 g/l with extremes ranging from 7.7 to 29 g/l. Antistreptolysins O (ASLO) were positive (greater than 200 units/ml) in 61.54% (n = 16) of patients. The nephrotic syndrome was pure in 57.69% (n = 15) and impure in 43.31% of cases (n = 11) ( Table 3 ).

The patients received diuretics in 92.30% (n = 24) of cases, and antihypertensive drugs were used in 19.230% (n = 5) of cases. Apart from oral corticosteroid therapy which was the basic treatment, two (2) patients received a bolus of methyl prednisone, i.e., a frequency of 7.70%. In 84.61% (n = 22) of cases the patients were corticosensitive and 3.85% (n = 1) were corticosensitive. There is one (1) case of death, i.e., 3.85% ( Table 4 ). Out of two patients who developed corticoresistance, one (1) had received a renal biopsy puncture (PBR) which had objectified segmental and focal hyalinosis.

ASLO: antistreptolysine O; CRP: C-reactive protein.

Over an 11-month period, 3758 children were admitted to pediatrics, including 26 with NS, i.e., a hospital frequency of 0.69%. This prevalence is lower than that reported by Keita et al. in Senegal in 2017 in a study carried out among children aged 2 to 12 years [22] with 1.56%. Our rate is close to that reported in a study by Moyen et al. on nephrotic syndrome in children aged 3 to 17 years at the University Hospital of Congo Brazzaville with 0.80% [7] . The difference in recruitment mode as well as the study area could explain this variation in frequency. Indeed, our study was done in a department that only cares for children from 5 to 15 years old. A larger study concerning children aged 0 to 15 years would make it possible to have a prevalence of nephrotic syndrome in the pediatric population.

The average age of our patients was 8 ± 2.99 years and the age range of 5 to 10 years was the most common with 57.69%. According to the literature, SN in children usually occurs between the ages of 2 and 12 [9] [19] [23] . Gbadoé AD et al. reported a mean age between 6 and 8 years in Black Africa [5] . Serre J. et al. had found an average age of 4.6 years in India [13] and Loire, Deschenes G reported an average age of 4 years in France in 2015 [24] . Our result is in harmony with H Savadogo’s in Ouagadougou in 2019 [25] who had found an average age of 7 years 5 months and lower than the result reached by Moyen et al. in Congo Brazaville who reported an average age of 10 years 8 months [7] . This result could be explained by the fact that the majority of our patients were 5 to 10 years old and that the nephrotic syndrome most often occurs in children aged 2 to 12 years [9] . In most of the literature data the nephrotic syndrome was predominant in the male sex [26] [27] . In our study, the sex ratio was 1.3 in favor of boys. Okoro BA et al. in Nigeria in 2000 [28] and H Savadogo [25] had found a sex ratio of 1.28 and 1.3 respectively. However, this male predominance has not always been found. When nearing adolescence, there is a tendency towards a cancellation of the male predominance [1] . The fragility of the male sex due to the XY chromosome could explain the male predominance although there is no statistically significant link between sex and SN [29] .

In our series, 76.92% of the patients came from rural areas. This result could be explained by the unbalanced diet and exposure to many triggering factors such as infections that could have been missed or poorly managed in rural areas. The majority of children presented late, with 61.54% more than 2 weeks after the onset of symptoms, 26.92% between 7 and 14 days and 11.54% within a week. This delay in consultation could be explained in our context where self-medication and the use of traditional products constitute the first line of care sought by the population, for cultural but also economic reasons. Rural children may also report later than urban children since more resources are needed to reach the hospital, which families do not always have immediately. Edema represented the reason for consultation present in all our patients. It was sometimes associated with abdominal pain and dyspnea in rare cases. The edema was generalized (edema of the lower extremities, ascites, morning swelling of the face and hydrocele in boys) in 84.62% of cases. This is similar to the results of Savadogo et al. [26] where edema was observed in 86% of cases at presentation. This may reflect an aggravation of the disease given the delay in the consultation.

Hypertension is a criterion for SN impurity. The risk of HYPERTENSION with SN is higher in black subjects [29] . In our series, high blood pressure was found in 23.07%. This prevalence is similar to that reported by Oukrif et al. in Algeria in 2017 [30] with a prevalence of 21%. A study by Ndogon et al. in Senegal in 2017 [3] reported a lower percentage of 15%. A correlation between the risk of arterial hypertension and the age of occurrence greater than 8 years in children with NS was observed in a Chinese study [31] . The older age of the children in our study may be consistent with this. It is also important to note that hypertension and the “impurity” of SN suggest a secondary form of SN or even a nephritic/nephrotic syndrome, which has a pathophysiology and a course of the disease different from those of primary SN. The differences in the composition of the cases between the studies can therefore have an impact on these associations.

At the physical examination, 14 patients presented a pallor (53.84%). This anemia could be explained by the low socioeconomic level of our patients, mostly from rural areas, because this segment of the population was the most affected by nutritional deficiencies including iron deficiency. Fever was found in 11.54% of cases (n = 3). The increase in the excretion of transferrin in the urine in SN could contribute to a decrease in hemoglobin. In our series, 22 patients had anemia, i.e., a frequency of 84.62% with an average value of 9.4 g/dl. Anemia was also common in the study by H Savadogo et al. [25] , occurring in 95.3% of patients with an average Bh of 10.3 ± 2.6 g/dl. This result could also be explained in our context by the insufficiency of a balanced diet and pre-existing anemia, as well as chronic helminth infections.

By definition, 100% of our patients had low serum protein and albumin levels with respective averages of 41.19 ± 12.41 g/L and 18.46 ± 5.97 g/L. Similar values were reported by H Savadogo et al. [25] , Keita et al. in 2017 [23] and Ndongo A et al. in Senegal in 2016 [3] . This result could be explained in our context by the Pu of the 24 hours which was less than 100 mg/kg/24H in 65% of cases. The massive proteinuria of the 24 hours at the level of the SN had been reported by several authors in the literature [6] [29] . In our series, the 24-hour proteinuria was between 50 and 100 mg/ kg/d in 65% of cases with an average value of 82.78 mg/kg/d. Sfaihi et al. in 2010 [15] and A Ndongo et al. in 2016 in Senegal [2] had reported mean values higher than ours respectively with 100 mg/kg/d and 113.70mg/ kg/d. Our result was significantly lower than the values found in the literature, this result could be explained by the consultation period which was in the majority of cases between 2 to 4 weeks.

In our series, the SN was pure in 57.69% (n = 15) and impure in 42.31% of cases (n = 11). According to literature data, pure SN was predominant in the majority of cases. NS associated with hypertension and/or hematuria and/or renal dysfunction is defined as impure NS [4] [17] [32] [33] . H Savadogo et al. [26] had reported a rate of 43.2% of pure SN and 56.8% of impure SN in their cohort. This result could be explained by the high frequency of ASLO positivity in our study and the higher risk of most kidney diseases in people of African origin.

Primary nephrotic syndrome is a glomerular nephropathy that requires long-term oral corticosteroid therapy [31] . This treatment regimen has been reported by several authors throughout the literature [31] [34] . Nephrotic syndrome responds quickly to corticosteroid therapy with the disappearance of proteinuria at 1 month in 90% of cases [35] . In our study we found a sensitivity to corticosteroid therapy in 84.61% of cases with one case of corticosteroid dependence, i.e., 3.85% and two patients developed resistance corticosteroid therapy, i.e., in 7.69% of cases. Keita et al. in 2017 [23] and Ndongo et al. in 2016 [3] , all in Senegal respectively reported corticosensitivity in 77% and 78% of cases and corticoresistance in 13% and 22% of cases. On the other hand, H Savadogo et al. in Ouagadougou [26] reported 56.7% corticoresistance, 40% corticosensitivity and 3.3% corticodependence.

We observed that the nephrotic syndrome in children at the National Hospital of Zinder (HNZ) represented 0.69% of children admitted to pediatrics during the study period. The age group of 5 to 10 years was the most found. The male sex was the most represented. In this series, the edemato-ascitic syndrome was the main clinical sign. The improvement of the technical platform to carry out the RBP in case of indication and the carrying out of the anatomopathological examinations as well as the establishment of social security, will undoubtedly make it possible to improve the care of the child’s nephrotic syndrome at the HNZ.

The insufficiency of the technical platform was ended by the non-realization of the Renal Biopsy Puncture (RBP) in case of indication (cortico-resistance, corti codependency).

The lack of financial resources hindered the realization of certain examinations necessary for the etiological diagnosis (search for sickle cell anemia, hepatitis B, syphilis, lupus...).

All the authors have contributed to the realization of this work.