Kidney and urinary tract manifestations in inborn errors of immunity

Background Kidney and urinary tract disorders represent an underrecognized but clinically important comorbidity in children with inborn errors of immunity (IEI). This study aimed to characterize the spectrum, frequency, and associated factors of kidney and urinary tract manifestations in pediatric patients with IEI to support early diagnosis and follow-up. Method This retrospective single-center study included pediatric patients with IEI and kidney or urinary tract involvement. IEIs were classified according to the 2024 IUIS classification, and nephrological diagnoses were based on current diagnostic criteria. Results Among 447 pediatric patients with IEI, 54 (12.1%) had kidney or urinary tract involvement. Consanguinity was present in 66.6% of these patients. Syndromic combined immunodeficiency was the most common IEI category (35.1%), and glomerular diseases were the most frequent kidney manifestation (29.6%). Patients with nephrological presentation were diagnosed with IEI at a significantly younger age and had a shorter diagnostic delay than those with immunological presentation (both p<0.001). Proteinuria, the most common nephrological finding, was associated with poorer overall survival (log-rank p=0.042). The age at first nephrological manifestation differed significantly across IEI categories (p=0.005), occurring earliest in patients with complement disorders. Chronic kidney disease was present in approximately one-forth of the patients and 16% required kidney replacement therapy. Conclusion Kidney and urinary tract manifestations are common and heterogeneous in pediatric IEI and vary according to the underlying immunological diagnosis. Early recognition of these manifestations may facilitate timely IEI diagnosis and underscores the importance of close collaboration between nephrologists and immunologists.