Complete Remission in Idiopathic Membranous Glomerulonephritis

Department of Pathology, County Hospital Veszprém, H-8200 Veszprém Pob. 205 (Hungary) Dear Sir, Idiopathic membranous glomerulonephritis (IMGN) is a disease with a variable course. Its natural history indicates that complete remission occurs in 15-63% of patients with IMGN with stable renal function [1, 2]. Little attention has been paid to the clinical and histological alterations which definitely play a key role in late remission. It is known that remission time differs case by case, but factors which have an effect on remission time remain undefined. In our series, complete clinical remission – defined as a reduction of proteinuria to 0.2 g/day or less – was observed in the case of 41 followed up patients of 100 with IMGN after a mean interval of 8.4 ± 6.6 years (3-22) from the time ofthe first renal biopsy. Twenty-seven patients became symptom-free in the first 5 years. In the case of 7 patients, it took 5-10 years, and in another 7 patients, it took more than 10 years to become symptom-free. At the time of renal biopsy, the degree of proteinuria and mean serum creatinine concentration were significantly higher and the average level of creatinine clearance (Ccr) was significantly lower in the patients ofthe late remission group (table 1). No patient was hypertensive. Renal biopsy showed stage 1 glomerular lesion in 10 patients, stage 2 in 23, stage 3 in 7 and stage 4 in 1 patient. Four patients had mild tubulointerstitial (TI) lesion. No patients in this series had vascular lesion. Ultrastructural morphometric analysis was used to measure the size of the subepithelial electron-dense deposits (SED) [3] and the thickness of the glomerular basement membrane (GBM), according to Osawa’s method [4]. The average size ofthe SED was significantly larger in the late remission group compared to the other groups. The GBM was significantly thickened in the patients who entered complete remission 10 years later after the first renal biopsy (table 2). We compared the length of time between biopsy and remission and found good correlations when observing: (1) Ccr (r = -0.625, p < 0.001); (2) proteinuria (r = 0.73, p < O.01; fig. 1); (3) SED (r-0.61, p < 0.001; fig. 2); (4) GBM (r = 0.543, p < 0.002). Two thirds ofthe patients with short remission were treated with steroid (methylprednisolone) alone (13 cases) or steroid combined with im-munosuppressant (cyclophosphamide) (4 cases) drugs. Despite the drug therapy, 7 cases entered complete remission after 10 years. These results are in accordance with previous observations. Some authors report late remission in patients with large, numerous deposits and thickened GBM. However, no study has been published about the mor-phometric analysis of deposit size and GBM thickness in patients with IMGN and their role in remission time length. According to Franklin [1] and