Glomerular hypertrophy in relapsing minimal change nephropathy

Clinicopathological and morphometric analysis of glomerular hypertrophy was conducted using biopsies from 89 patients with minimal change nephrotic syndrome (MCNS). Of the 89 patients, in 69 with complete remission and in 20 with one or more relapses, various clinical and morphometric parameters were compared to 15 normal controls. Proteinuria was more severe and serum creatinine (Cr) concentration significantly higher in patients with relapse of proteinuria. The morphometric analysis showed that the sizes of (1) glomerular tufts and (2) glomerular capillaries were significantly larger in patients in the relapse group than in the remission or control groups, but no difference in the size of Bowman's capsule was found between the two MCNS subgroups. The intertubular capillaries were narrower in patients who failed to reach prompt complete remission. A negative correlation between intra- and extraglomerular capillary size was evident (r = -0.83, p < 0.001). A definitive correlation was detected between the circumference of glomerular capillary loops and the degree of proteinuria (r = 0.89, p < 0.001). The mean tubulocapillary diffusion distance was significantly longer in biopsies of the patients in relapse and showed a close significant correlation with serum Cr level (r = -0.87, p < 0.001) and intertubular capillary size (r = -0.87, p < 0.001). These data suggest that extra- and intraglomerular hemodynamic alterations in MCNS lead to glomerular hypertrophy, and dilatation of the glomerular capillary loop plays a key role in the relapse of MCNS.