[A case of combination therapy with MMF and steroids for idiopathic membranoproliferative glomerulonephritis].

A 26-year-old man diagnosed with nephrotic syndrome was administered steroid monotherapy. Urinary protein excretion was 2-3 g/day despite the therapy. Percutaneous renal biopsy revealed Type I idiopathic membranoproliferative glomerulonephritis (IMPGN). Although intravenous steroid therapy at the dose of 1,000 mg/day for 3 days was administered, proteinuria persisted at the level of 1 g/day. Renal dysfunction (cystatin C, 1.33 mg/L) was evident. Strong inflammation was suggested by occult blood (3+) and urinary (red blood cells: 30-50/high power field) sediment. We considered steroid monotherapy to be ineffective, and initiated combina-tion therapy with mycophenolate mofetil (MMF) and steroids. Consequently, urinary protein excretion moderately decreased to 0.34 g/day without adverse events or worsening of the renal function. The steroid quantity could be reduced without relapse. Subsequently, we were able to reduce the dose of MMF gradually, then terminated the medication. IMPGN is a rare disease with a poor renal prognosis. Recently, MMF therapies for IMPGN have been attempted, but there are few cases in Japan. Our case suggests that combination therapy with MMF and steroids is effective and safe for treating IMPGN.