Sulfadiazine-associated obstructive nephropathy occurring in a patient with the acquired immunodeficiency syndrome

A 45-year-old man with the Acquired Immunodeficiency Syndrome (AIDS) and CNS toxoplasmosis presented with acute renal failure, hematuria, and renal colic shortly after starting treatment with sulfadiazine. Ultrasound examination of his kidneys was suggestive of intraparenchymal crystallization of sulfadiazine. His renal failure and ultrasound findings rapidly resolved with alkaline hydration. On rechallenge with sulfadiazine, he again developed renal insufficiency and ultrasonic findings consistent with stones. The use of sulfadiazine in the treatment of CNS toxoplasmosis in AIDS patients should be monitored carefully with the recognition that this form of crystalline-induced acute renal failure can occur in a dehydrated patient.