Acute renal failure due to bilateral ureteral stone impaction in an HIV-positive patient.

A 51-year-old HIV-positive man treated with atazanavir for 9 months presented with anuria following right flank pain. Laboratory examination indicated renal insufficiency, and abdominopelvic computed tomography scanning showed bilateral hydroureteronephrosis, but no stones were visualized. Endoscopic procedures were performed to investigate the causes of ureteral obstruction and, if possible, to insert Double-J stents in the ureters. A yellowish stone composed of pure atazanavir was found at the right ureteral orifice, and retrograde pyelography revealed a filling defect in the left ureter found to be caused by an atazanavir stone. The patient's renal function recovered after removal of these stones.