In order to define the type of renal disease, renal biopsy was performed in 1304 patients, aged 14-72 years. Their biopsies were processed for light and immunofluorescence microscopy, and electron microscopy in some cases. The diagnosis of primary glomerular disease was confirmed in 716 patients with the following incidence: minimal change nephrotic syndrome in 52 (7.2%), focal segmental glomerulosclerosis in 72 (9.9%), membranous nephropathy in 97 (13.5%), IgA nephropathy in 85 (11.8%), diffuse mesangial glomerulonephritis (GN) without IgA in 32 (4.4%), focal mesangial GN in 97 (13.5%), membranoproliferative GN in 59 (8.4%), acute GN in 88 (12.3%), crescentic GN in 53 (7.4%) and sclerosing GN in 46 patients (6.4%).
