Iron deposition in renal biopsy specimens from patients with kidney diseases

This study was performed to investigate the correlation between clinical pa rameters and! grading of iron deposition in renal biopsy specimens from 102 patients with various kidney diseases. Iron deposition in renal tissues wa s detected by Berlin blue staining. The extent of iron staining was semiqua ntitatively graded as negative (Fe-), grade 0, or positive (Fe+), including faint, grade 1; moderate, grade 2; or severe, grade 3, by light microscopy . Thirty-four of 102 patients (33%) showed positive iron staining. Fe+ pati ents had various renal diseases, mainly consisting of 12 patients with immu noglobulin A nephropathy and 5 patients with benign nephrosclerosis. Mean a rterial pressure (MAP), serum creatinine (sCr) levels, incidence of hematur ia, and urinary N-acety beta -D-glucosaminidase (u-NAG) levels in Fe+ patie nts were significantly greater than those in Fe+ patients, and u-NAG levels correlated positively with the extent of iron deposition. Study patients w ere tentatively divided into two groups according to the extent of iron dep osition:. group A, patients with grades 2 and 3 staining, and group B, pati ents with grades 0 and I staining. In group A, MAP, sCr level, urinary prot ein excretion, and the incidence of hematuria were significantly greater th an in group B. Our results suggest that the amount of iron deposition in re nal tissue may contribute to the progression of chronic renal disease and m ay be an early and sensitive indicator of renal damage in certain renal dis eases. (C) 2001 by the National Kidney Foundation, Inc.