ABSTRACT
Membranous nephropathy (MGN) is a common cause for nephrotic syndrome in adults. Renal failure usually develops gradually in patients with MGN and rapid deterioration of renal function is a rare complication. Moreover, the development of crescentric glomerulonephritis (CGN) as a cause of acute renal failure (ARF) in patients with preexisting MGN is very rare. We report 20-year-old male patient with MGN who presented with ARF due to superimposed CGN. He had been diagnosed as idiopathic MGN and his renal function was maintained within normal range. After 13 months of conservative treatment, ARF was developed and renal biopsy was performed to differentiate the possible causes of ARF. Renal biopsy revealed diffuse crescents formation on preexisting MGN. Anti-GBM antibody and ANCA were not detected. This patient was treated with combination therapy including methylprednisolone pulse therapy followed by high dose steroid and cyclophosphamide. His renal function was improved significantly 2 weeks after treatment. In conclusion, when unexplained ARF in patient with MGN develops, prompt investigation for superimposed conditions including CGN is necessary and repeat renal biopsy should be considered.