Recurrent nephrolithiasis associated with atazanavir use

A 64-year-old man with HIV on antiretroviral therapy (including atazanavir, a protease inhibitor) presented with left flank pain, nausea and vomiting. A kidney stone was suspected, and a CT scan demonstrated left hydronephrosis but failed to demonstrate nephrolithiasis or extrinsic compression. The patient had a ureteral stent placed which relieved his symptoms. A few months later, he underwent left ureteroscopy and a large ureteral calculus was found. The stone was removed and analysis showed 43% atazanavir and 57% calcium oxalate. Several months later, the patient developed flank pain on the opposite side. A renal ultrasound suggested right-sided nephrolithiasis and he subsequently underwent ureteroscopy with laser lithotripsy of two stones. Stone analysis showed that they were composed of 100% atazanavir. This case highlights the fact that patients treated with protease inhibitors remain at risk for developing nephrolithiasis. Ultrasonography can be a useful diagnostic tool in the setting of these radiolucent calculi.