Nephrotic syndrome and IgA nephropathy in polycystic kidney disease.

A 70-year-old man with polycystic kidney disease developed nephrotic syndrome, deteriorating to renal insufficiency. Histological examination revealed IgA nephropathy. With treatment of prednisolone, an angiotensin-converting enzyme inhibitor, and an angiotensin II receptor-blocker, his proteinuria markedly decreased and renal function was stabilized. This case supports the idea that renal biopsy is needed in patients with polycystic kidney disease with nephrotic-range proteinuria, for appropriate treatment and prevention of renal failure.