Spironolactone Plus Full-Dose ACE Inhibition in Patients with Idiopathic Membranous Nephropathy and Nephrotic Syndrome: Does It Really Work?

We have studied the effects of add-on spironolactone treatment (100 mg/day) in 11 patients with idiopathic membranous nephropathy (IMN) and >3 gm proteinuria/day despite angiotensin converting enzyme (ACE) inhibitor therapy titrated to a systolic/diastolic blood pressure <120/80 mmHg. Blood pressure, 24-hour urinary protein excretion, and creatinine clearance were measured prior to, after two months of combined therapy, and after a 2-month withdrawal period of spironolactone. While systolic and diastolic blood pressure decreased significantly after spironolactone therapy, proteinuria did not improve. Serum potassium increased significantly as well, with three patients requiring resin-binding therapy. Thus, spironolactone seems to have no additional antiproteinuric effects over ACE inhibitor therapy in patients with IMN and nephrotic syndrome and carries the risk of significant hyperkalemia.