Indinavir urinary stones as origin of upper urinary tract obstruction

The development of HIV protease inhibitors has dramatically improved the treatment prognosis of HIV-infected patients. The treatment, however, is associated with the potential for adverse events that are unique to protease inhibitors. One of them, Indinavir, can lead to the development of urinary stones. Three weeks after starting treatment with Indinavir, Zidovudine and Lamivudine, a 66-year-old patient developed symptomatic hydronephrosis on the right side due to multiple Indinavir stones blocking the ureter. Microhematuria and characteristic crystals were found in the urine. After interruption of treatment and increased fluid intake, the crystallurea was not longer detectable and the patient became asymptomatic within 3 days. Nephrostomy and ureteral stent placement were not necessary. Patients on treatment with Indinavir are required to maintain a fluid intake of at least 1.5-2 l/day to reduce the risk of crystallization and urinary stones. Pharmacologic metaphylaxis to prevent crystallization is not recommended.