Minimal change disease and idiopathic membranous glomerulonephritis in adults. A quantitative study

Fifteen renal biopsy specimens from adult patients with minimal change disease (MCD) and twelve with early stages of idiopathic membranous glomerulonephritis (MGN) for whom light, electron and immunofluorescence microscopy and full clinical data were available were examined quantitatively. As controls 6 biopsy and 9 autopsy specimens of the normal kidneys were used. Morphometric investigations were performed by means of a computer image analysis system to evaluate whether morphometric analysis is helpful in differential diagnosis of MCD and early MGN in adults and to study whether changes in quantitatively analyzed glomeruli correlated with the clinical data. The mean values of total glomerular area, total glomerular cells per total glomerular area, total glomerular cells per unit of glomerular area, mesangium (% of total glomerular area) and relative interstitial volume in both MCD and MGN were increased in comparison with normal controls, most of them significantly. In MGN the mean values of total glomerular area, total glomerular cells per total glomerular area and relative interstitial volume were significantly greater than those of the minimal change group. In MGN but not in MCD there was a significant positive correlation between interstitial volume and serum creatinine. Correlations between proteinuria and total glomerular cells per unit of glomerular area, were weak and not significant in both MCD and MGN groups. Although our results give clear evidence that quantitative analysis can not be used instead of light microscopy, electron microscopy and immunohistochemistry, it may be helpful in differential diagnosis of MCD and early stages of MGN in adults, particularly when electron microscopy is not available. In particular, precise evaluation of the interstitial lesions seems to be extremely useful in these cases.