Celiac Disease in Children with Idiopathic Nephrotic Syndrome—A Retrospective Cohort Study

Objective: Idiopathic nephrotic syndrome (INS) is a rare, relapsing kidney disease. Trigger for relapses, among others, may be exposure to gluten in patients with INS and celiac disease (CD). CD is a gluten-sensitive disorder. The prevalence of CD ranges from 1% in the general population to 8% in patients with autoimmune diseases. The aim of the study was to assess the incidence of CD in patients with INS and the influence of a gluten-free diet on the course of INS. Material and Methods: A retrospective cohort study was conducted on 147 patients hospitalized between February 2020 and September 2024 in a single medical center. Patients were categorized into two groups: 98 patients with INS and 49 from the control group. The analysis included age, gender, total dose of glucocorticoids (GCs), duration of INS, serum levels of immunoglobulin class A (IgA) and G (IgG), the presence of antibodies against tissue transglutaminase (tTG) and endomysium (EMA), and urine analysis. A medical questionnaire regarding pathological symptoms during infancy and allergic diseases of patients and family members was conducted. Results: CD was diagnosed in 8% of patients with INS. A total of 66% of patients with INS and CD who followed a gluten-free diet had no or less frequent relapses. Conclusions: CD is more common in patients with INS than in the general population. A gluten-free diet in patients with INS and CD may decrease the frequency of nephrotic proteinuria relapses. CD may be oligosymptomatic, and it is important to search for it in all patients with INS. Owing to the small number of patients with CD among INS in the study, this issue requires further research.