Endourological management of a rare radiopaque ritonavir-composed urinary calculus

Protease inhibitors are a source of nephrolithiasis in HIV + patients, and these stones are described as not detected by CT. While urinary stones are commonly associated with certain protease inhibitors, stones composed of ritonavir are rare. We present the case of a 58-year-old female on ritonavir-boosted atazanavir who presented to our clinic complaining of gross hematuria and flank pain secondary to a ureteral stone. Surgical removal revealed the stone to be composed of 100% ritonavir with no usual urinary stone components. This is the first report of an HIV medicine stone being detectable by CT scan described as 100% ritonavir.