MO1040: Idiopathic Nephrotic Syndrome After 10 Years of Age: Is Systematic Renal Biopsy Appropriate?

Abstract

Abstract BACKGROUND AND AIMS Renal biopsy (RB) is recommended at diagnosis for children presenting with isolated nephrotic syndrome (NS) after the age of 10–12 years, unlike in younger children, because of a higher frequency of other diagnoses than MCD or FSGS. Recent reports, local practices and new serological biomarkers for membranous nephropathy now question this approach. Therefore, the objective of our study was to evaluate the causes of NS and indications for RB in a population-based cohort of adolescents with NS. METHOD We conducted a retrospective multicenter study, including children aged 10–18 years diagnosed with Idiopathic-like NS between December 2007 and June 2020 in 35 paediatric and 3 paediatric nephrology (PN) departments of the Paris area (NEPHROVIR network) and patients with Idiopathic-looking NS biopsied in the three PN departments. RESULTS A total of 103 children were included (54 males). The mean age at diagnosis was 13.4 ± 2 years. A renal biopsy was performed in 76 patients: at presentation because of atypical symptoms (such as hypertension, macroscopic haematuria, organic renal failure) in 15 or for no other reason than age in 39 and after 4 weeks for steroid resistance +/– atypies in 22 patients. Histological findings were MCD (n = 49), FSGS (n = 13), mesangial proliferation (n = 3), membranous nephropathy (n = 6) and IgAN (n = 5). CONCLUSION NS was secondary in only 11% of adolescents presenting with Idiopathic-like NS, and first-line treatment with oral prednisone was appropriate in all cases. In addition, more than 40% of RB could have been avoided in steroid-sensitive NS patients. Finally, we propose that RB should only be performed in case of atypical clinical or biological history or steroid resistance after 4 weeks, as in the younger population.