Idiopathic membranous glomerulopathy. Quantitative study of the subepithelial deposits and glomerular basement membrane including clinico-morphological correlations

Thirty-one renal biopsy specimens from patients with idiopathic diffuse membranous glomerulonephritis (MGN) for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available were examined quantitatively and compared with six normal controls, Morphometric investigations of the electron micrographs were done using a computer image analysis system to clarify conflicting opinions regarding the relationship between the clinical phase of MGN and the electron-microscopic density of the deposits and the thickness of the glomerular basement membrane (GEM), Two groups of MGN were selected: EMGN - relatively early cases (stage I and stage II according to the scheme proposed by Churg's group) and AMGN - advanced cases (stage III), In agreement with qualitative descriptions in MGN there was a distinct thickening of the GEM in comparison with normal controls (in both groups P < 0.001). There were significant positive correlations between deposit area per GEM area and proteinuria (r = 0.73, P < 0.002 in EMGN and r = 0.83, P < 0.001 in AMGN). The area of these deposits did not correlate with renal function and prognosis. The negative correlations between GEM thickness and hematuria were also clear in the EMGN and AMGN groups (respectively r = -0.74, P < 0.05 and r = -0.95, P < 0.02), but because of the small number of cases (respectively 8 and 7) further studies are needed to confirm this association, Correlation between the other parameters were weak and not significant.