1063 Presentation, treatment, and outcome of IgA nephropathy in children: comprehensive characterization of a Croatian single centre cohort

Abstract Background and Aims IgA nephropathy (IgAN) is a complex disease diagnosed only upon evaluation of a kidney biopsy. Since the threshold to perform this invasive procedure is higher and symptoms usually more indolent in children, the true prevalence might be underestimated, with fewer studies examining the presentation, treatment, and outcome of IgAN in paediatric population. Moreover, there is a substantial heterogeneity of clinical presentation and pathological features between geographical locations, with fewer data available for region of central and southern Europe. We therefore aim to provide a conscientious description of a paediatric IgAN cohort followed for an extended period of time in a centre caring for most of the Croatian paediatric patients. Method Single centre retrospective study of children newly diagnosed as IgAN since 2011 and followed for >2 years in a tertiary referral centre for paediatric nephrology of the Republic of Croatia. Results Total of 15 paediatric (150 mg/day) and hematuria (>5 RBC/mm3 in uncentrifuged urine) at the time of the biopsy, with the mean age of 12.2 ± 3.6 years. The median eGFR was 87 (69 – 111) mL/min/1.73m2 and the median value of proteinuria 260 (150 – 370) mg/day. More specifically, 2 patients had mild proteinuria (50 mg/kg/day). The results of biopsy in terms of MEST-C score showed M1 in 4, E1 in none, S1 in 3, T1 in 4, T2 in 0, C1 in 2 and C2 in none of the patients. The IF was positive for IgA and C3 in all patients, and in 1 for C1q. There was no significant correlation between C3 intensity values (0-4+) and 24 h proteinuria (r = 0.49, p = 0.06) or eGFR (r = −0.22, p = 0.43). Hypertension (≥95 percentile for age) was present in 2 (13%) patients. The median risk of a 30% decline in eGFR or progression to end-stage renal disease 5 years after renal biopsy calculated by International IgAN prediction tool for use in paediatric patents was 8.03% (4.58 – 11.27). Initial presenting episode was treated with ACEi in 7 (47%) and with glucocorticoids in 4 (27%) patients. There was no significant difference in proteinuria (p = 0.19) or risk of decline in eGFR or progression to ESRD (p = 0.16) among treated and untreated patients. In all of the treated patients proteinuria reached a target of