Background. Although several registries collecting data of patients with kidney diseases exist, there are only a few registries which specifically collect data relating to renal biopsy; one such registry is the Italian Registry of Renal Biopsies (IRRB). The aim of this study was to report on the relative frequency of nephropathies according to gender, age at time of biopsy, clinical presentation and renal function, based on the histologic diagnosis during the years 1996 to 2000. Methods. We evaluated data relating to 14607 renal biopsies, provided by 128 renal units in Italy. Data entry was performed by using the Internet-based database directly (URLhttp://www.irrb.net). Clinical presentation was defined as urinary abnormalities (UA), nephrotic syndrome (NS), acute nephritic syndrome (ANS). Renal diseases were divided in four major categories: (1) primary glomerulonephritides (GN); (2) secondary GN; (3) tubulointerstitial nephropathies (TIN); and (4) vascular nephropathies (VN). Results. Primary GN, TIN, and VN were more frequent in males compared to females while secondary GN was more frequent in females. Diseases whose frequency was higher in males were IgA nephropathy (IgAN), benign nephroangiosclerosis (BNA), and acute tubular necrosis (ATN). A significantly higher frequency of immune-mediated secondary GN, as well as primary GN, including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and mesangiocapillary GN (MCGN), was shown in females. Primary and secondary GN, TIN, and VN were more frequent in the range 15 to 65 years of age. At the time of biopsy 77% of primary GN and 61% of secondary GN presented with normal renal function. Acute renal failure (ACR) was more present in TIN (52%), while chronic renal failure (CRF) was more frequent in VN (47%). Conclusion. We believe collection of data relating to renal biopsies in a national registry is a useful tool for nephrologists in that it meets one of the current challenges facing the clinical research enterprise. The availability of these data will allow epidemiologic studies in health care to answer the several open questions in both prevention and treatment of renal diseases.
