Evaluate Rituximab Treatment for Idiopathic Membranous Nephropathy

The Membranous Nephropathy is one of the most common cause of Nephrotic Syndrome of adults. In 2/3 of patients the cause of the disease is idiopathic. This can also be referred to as idiopathic membranous nephropathy (IMN).The most of these patients are treated by non immunosuppressive symptomatic treatment (NIST): antiproteinuric and antihypertensive blocking the rennin-angiotensine system. However, the patients resistant to antiproteinuric treatment risk to develop an end stage renal disease (ESRD). Rituximab has been recently used in patients suffering of nephrotic syndrome related to IMN in four international studies. Rituximab appears effective and safe in reducing proteinuria in nearly 60% of patients. The primary outcome of the investigators prospective randomized study is to determine whether or not the Rituximab associated with NIST is more effective than non immunologic symptomatic treatment alone in inducing long term remission of proteinuria.