Volume Ratio of Glomerular Tufts to Bowman Capsules and Renal Outcomes in Nephrosclerosis

Abstract

BACKGROUND The concomitant appearance of glomerular collapse and enlargement is characteristic of the histological findings in nephrosclerosis. However, no previous study quantitatively examined the clinicopathological significance of this feature in patients with biopsy-proven nephrosclerosis. METHODS Renal biopsy specimens and follow-up data from nephrosclerosis patients with estimated glomerular filtration rates >30 ml/min/1.73 m 2 at diagnosis were retrospectively reviewed. Mean volumes for glomerular tufts (GV) and Bowman capsules (BV) were separately calculated, based on the measurement of all areas of glomerular tufts and Bowman capsules in a cross-section of biopsy specimens. The G/B ratio was defined as the ratio of GV to BV. The doubling of serum creatinine levels (DSC) and the initiation of renal replacement therapies (end-stage renal disease (ESRD)) were examined as renal outcome indices. RESULTS A total of 67 patients with biopsy-proven nephrosclerosis were included. Clinicopathological findings at biopsy, other than GV, were comparable among all patients, irrespective of G/B ratio. Overall, 25 patients (37%) developed DSC and 9 (13%) developed ESRD during the median observation periods of 7.8 and 8.5 years, respectively. Renal survival curve analyses indicated a significantly worse prognosis for patients with a low G/B ratio, as compared with those with a high G/B ratio. Cox hazard analyses for DSC identified low G/B ratio as a significant predictor, but not low GV or BV. CONCLUSIONS These results suggest that the quantitative evaluation of G/B ratio may detect subtle abnormalities in the glomerulus, indicating the subsequent renal outcomes of nephrosclerosis patients.