Background: This study was conducted to investigate retrospectively the indications for renal biopsy (RB) in native kidneys and to analyze pathological findings in a single tertiary pediatric hospital in Southern Italy for the last 36 years.

Methods: All patients who underwent RB at our hospital from 1979 to 2014 were included. All renal tissue specimens were studied under light and immunofluorescent microscopy, while electron microscopy was performed only for specific clinical indications.

Results: The study group included 213 patients (female 43.2%) who underwent 225 percutaneous native kidney biopsies. Median age was 10.4 years (range 0.6–24 years). The most frequent indication for RB was nephrotic syndrome (44.4%), followed by proteinuria (27.6%), asymptomatic hematuria (17.3%) and acute kidney injury (9.8%). Gross hematuria appeared after biopsy in less than 5% of the patients, but none of them needed blood transfusion. Adequate renal tissue sample was obtained in 95.5% of the renal biopsies. Primary glomerulonephritis (GN) was the most common finding (61.4%), followed by secondary GN (21.4%), tubulointerstitial diseases (3.7%) and hereditary nephropathy (2.8%), while in 10.7% of the cases, normal renal tissues were found. According to histopathological diagnosis, the most common causes of primary GN were IgA nephropathy (20.9%), followed by minimal change disease (18.1%) and focal segmental glomerulosclerosis (11.6%).