Clinical and pathohistological characteristics of biopsy-proven renal diseases in children in Croatia

There is little data on the spectrum of renal diseases among children in Croatia. A renal diseases registry has been set up recently in an attempt to address this issue nationwide. Here we report the results of a retrospective analysis of clinical and histopathological data of 565 children presenting to 7 hospitals in Croatia from 1991 to 2004 in whom kidney biopsy was performed. The most common indications for biopsy were nephrotic syndrome (39.2%), asymptomatic proteinuria/hematuria (21.7%) and nephritic syndrome (16.9%). All biopsies were analysed by light, immunofluorescent and electronmicroscopy. Primary glomerular diseases accounted for 65.4% of all biopsies, followed by secondary (14.8%) and hereditary glomerular diseases (12.0%). Among primary glomerular diseases the most frequent were focal segmental glomerulosclerosis (FSGS) (25.0%), mesangial proliferative glomerulonephritis (MEPGN) (19.2%) and IgA nephropathy (18.2%). The most common secondary glomerular diseases were Henoch-Schonlein purpura (HSP) ( 47.9%) and systemic lupus erythematosus (SLE) (35.4%). The most frequent hereditary glomerular disease was Alport syndrome (80.9%). In the group of children with primary glomerular diseases who presented with nephrotic syndrome the most frequent were FSGS (38.5%) and MEPGN (24.0%). Minimal changes glomerulopathy (MCG) accounted for only 10.9% cases. IgA nephropathy, primary or related to HSP, was the most common biopsy proven renal disease in Croatian children (20.0% of all cases). The analysis provided data on the frequency of histological renal lesions in children in Croatia. The higher frequency of FSGS among Croatian children in comparison with similar analyses in other countries deserves further evaluation.