RENAL CORTICAL INTERSTITIAL VOLUME IN MESANGIAL IGA NEPHROPATHY - DISSOCIATION FROM CREATININE CLEARANCE IN SERIALLY BIOPSIED PATIENTS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 47  (4) , 330-335
Abstract
Renal cortical interstitial fibrosis may be causally related to progressive decreases in glomerular filtration rate in a variety of renal diseases including glomerulonephritis. Renal biopsies (188) in 81 patients with mesangial IgA nephropathy were analyzed for the percentage of relative interstitial volume by a point-counting technique. The data were correlated with serum creatinine, endogenous creatine clearance and the patient''s age at biopsy. In addition, 81 biopsies taken immediately after cadaver transplantation from age-matched donors were used as controls for the interstitial volume measurements. There was a negative nonlinear correlation between percentage of interstitial volume and creatinine clearance (r = -0.601, P < 0.001). The correlations were not explained by age. Serial biopsies in 39 patients clearly demonstrated that the percentage of interstitial volume could be dissociated from creatinine clearance. The prognosis in individual patients for progression to chronic renal failure could not be predicted from the relative interstitial volume at initial biopsy. Patients with mesangial IgA nephropathy demonstrated higher interstitial volumes than age-matched cadaver donors (P < 0.001). Although interstitial volume and creatinine clearance are inversely related, the abilty to dissociate these 2 variables in serial biopsies draws into question the hypothesis that interstitial fibrosis is causally related to changes in creatinine clearance. Studies to validate this hypothesis should involve patients followed with serial biopsies and renal function studies. In mesangial IgA nephropathy, interstitial changes are most likely secondary to the activity of the glomerular process.