Idiopathic membranous glomerulonephritis: a clinicopathologic and quantitative morphometric study.

We evaluated clinical and morphological findings in 254 patients (138 men and 116 women), with idiopathic membranous glomerulonephritis (IMGN). The mean age was 44 years. At time of biopsy proteinuria was found in 98%, nephrotic syndrome (NS) in 45.2%, hypertension in 10%, elevated serum creatinine concentration of greater than or equal to 1.4 g/dl in 24%, and markedly decreased Ccr (less than or equal to 40 ml/min) in 12.5% of the patients. Of 254 patients, 51 (20%) were classified as Stage I, 131 (52%) as Stage II, 52 (20.5%) as Stage III, 9 (3.5%) as Stage IV and 11 (4.3%) as Stage V, which was a relapsing form. Both intraglomerular, peripheral electron dense deposit-size and mean thickness of the glomerular basement membrane (GBMt) were analyzed by ultrastructural morphometric methods. In patients with NS, both the mean deposit-size and the mean GBMt were largest when compared to all others (p less than 0.01). The largest subepithelial deposits (SED), in mean, were observed in Stages II and V, while the largest incorporated deposits (ICD) were measured in Stages II and IV. The mean GBMt was largest in Stage III. Furthermore, there were strong correlations between the degree of proteinuria and the deposit-size (r = 0.603, p less than 0.001), and GBMt (r = 0.456, p less than 0.001). The GBMt showed a correlation with serum creatinine concentration (r = 0.476, p less than 0.001) and Ccr (r = 0.471, p less than 0.001). We concluded that the size of the electron dense deposits and GBM thickness play an important role in the clinical manifestation of IMGN.