Julia R. Fielding, M.D. Brigham and Women's Hospital, Harvard Medical School Boston, Massachusetts

This HIV positive patient had undergone CT examination of the abdomen for another complaint two months prior to this exam. There was no evidence of obstructive uropathy. A non contrast enhanced CT scan was obtained as part of his work-up (Figure 1), (Figure 2), and (Figure 3).

Answer: Indinavir associated nephrolithiasis. The CT images tailored to examine the ureter (contiguous 5mm images) demonstrate bilateral hydronephrosis and obstructing ureteral stones.

Many HIV positive individuals are now treated with protease inhibitors, such as indinavir, which suppress virus replication by inhibiting HIV protease, an enzyme required to render HIV infectious. One of the side effects of indinavir is nephrolithiasis, occuring in 4% of treated individuals (1,2). The stones are relatively soft and friable, and conservative therapy consisting of hydration, analgesics and cessation of indinavir for a few days is often effective treatment.

References:

Anonymous: New Drugs for HIV Infection. Medical Letter on Drugs and Therapeutics, 38;35, 1996.

Rich JD, Ramratnam B, Chiang M, Tashima KT. Management of Indinavir Associated Nephrolithiasis. J Urol 158;2228, 1997