Idiopathic membranous nephropathy (IMN) is one of the common types of primary glomerular diseases and the most common cause of nephrotic syndrome in adults.

Poticelli regimen is the classic treatment, but cyclophosphamide has many toxic side effects. The period of glucocorticoid therapy is relatively long, and the adverse reactions caused by glucocorticoid therapy cannot be ignored. For patients who are unwilling to receive glucocorticoids and cyclophosphanide or who have treatment contraindications, cyclosporine can be used, mainly cyclosporine and tacrolimus, with the rapid overall effect but a high short-term relapse rate. In recent years, rituximab therapy has become a first-line treatment, with a high remission rate, and few side effects, but expensive. In terms of efficacy alone, the above regimen did not exceed Poticelli regimen. However, the toxic side effects of rituximab, cyclosporine may be lower than that of Poticelli regimen. Based on the preliminary experiment, this study explored a new treatment plan: low-dose rituximab combined with cyclosporine in the treatment of IMN, the efficacy is not inferior to Poticelli regimen, but the side effects are significantly reduced. The result will provide a good choice for IMN patients.

Inclusion Criteria:

1. age 18-70 years; serum albumin level <30 g/L;
2. estimated glomerular filtration rate (eGFR according to the CKD-EPI formula) ≥60 mL/min per 1.73 m2;
3. patients with a moderate risk of IMN and decline <50% in proteinuria despite blockade of the renin-angiotensin system 3 months before randomization;
4. patients at high risk or very high risk of IMN.

Exclusion Criteria:

1. secondary causes of MN;
2. being pregnant or breastfeeding;
3. uncontrollable active infectious disease;
4. immunosuppressive treatment in the preceding 3 months.