Renal biopsy findings in acute renal failure in the cohort of patients in the Spanish Registry of Glomerulonephritis.

BACKGROUND AND OBJECTIVES Renal biopsy in acute renal failure of unknown origin provides irreplaceable information for diagnosis, treatment, and prognosis. This study analyzed the frequency and clinicopathologic correlations of renal native biopsied acute renal failure in Spain during the period 1994 through 2006. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Acute renal failure was defined as a rapid deterioration of glomerular filtration rate, with or without oligoanuria or rapidly progressive renal insufficiency, including acute-on-chronic renal failure. Patients who were younger than 15 yr were considered children, those between 15 and 65 yr adults, and those >65 elderly. RESULTS Between 1994 and 2006, data on 14,190 native renal biopsies were collected from 112 renal units in Spain. Of these, 16.1% (2281 biopsies) were diagnosed with acute renal failure. The prevalence of the main clinical syndromes was different in the three age groups: Biopsy-confirmed acute renal failure in children was 5.7%, in adults was 12.5%, and in elderly increased significantly to 32.9%. The prevalence of biopsy-confirmed acute renal failure according to cause was as follows: Vasculitis, 23.3%; acute tubulointerstitial nephritis, 11.3%; and crescentic glomerulonephritis types 1 and 2, 10.1%. The prevalence of the different causes differed significantly according to age group. CONCLUSIONS The Spanish Registry of Glomerulonephritis provides useful information about renal histopathology in biopsy-confirmed acute renal failure. The prevalence of vasculitis and crescentic glomerulonephritis is high, especially in elderly patients. These data obtained from a national large registry highlight the value of renal biopsy in undetermined acute renal failure.