Clinical course and outcome of idiopathic membranous nephropathy in Japanese children

We retrospectively studied 12 Japanese children (8 boys, 4 girls) with idiopathic membranous nephropathy (IMN), aged 2.9-15.8 (mean 7.7) years at onset. All patients were identified through either screening or a routine urinalysis; proteinuria was present in all, haematuria, which was macroscopic in 4, in 11. Three had nephrotic syndrome (NS) at or soon after onset. Stages on electron microscopy, performed in 10 patients, were I in 3, II in 5 and III in 2. Steroids alone or with cyclophosphamide were administered to 5 patients, including the 3 patients showing NS. Complete remission of proteinuria occurred in 8 patients 0.3-1.6 (mean 0.6) years after onset, and proteinuria did not recur. After a follow-up of 1.6-11.6 (mean 5.9) years, these 8 patients were in complete remission and the remaining 4 had only mild proteinuria; none had hypertension or impaired renal function. Thus, we infer that IMN in Japanese children may have a better course and outcome than IMN in non-Japanese children. Based on a comparative study of Japanese (previously reported cases added to ours) and non-Japanese (mostly Caucasian) children with IMN, this was confirmed: it is possible that steroid therapy in Japanese patients is more effective in inducing remission of NS and preserving renal function.