A case of myasthenia gravis, who developed minimal change nephrotic syndrome during immunosuppressive therapy after thymectomy

Abstract

Myasthenia gravis is caused by antibodies against acetylcholine receptors and is treated with inhibition or elimination of antibody production. We report a 58-year-old woman who had been suffering from myasthenia gravis and underwent thymectomy in July 1995. Her myasthenic symptoms improved with immunosuppressive treatment using corticosteroid (100 mg/day) and azathioprine (100 mg/day). However she presented edema with massive proteinuria (7.54 g/day) and was admitted to our hospital on July 1997. She was diagnosed as having nephrotic syndrome and a renal biopsy was performed. The histological findings showed minimal change nephrotic syndrome. After pulse therapy with methylprednisolone (1 g/day × 3 days) following oral administration of prednisolone (60 mg/day), proteinuria disappeard after one month. Nephrotic syndrome is a rare complication in patients with myasthenia gravis. The increase in lymphokine production caused by thymectomy may be closely associated with the occurrence of nephrotic syndrome in spite of intensive immunosuppressive treatment in the present case. In this report, we also summarized reported cases of minimal change nephrotic syndrome with thymoma and myasthenia gravis.