Types of Stones

Crixivan Stones

Protease inhibitors are a new class of medication used to treat patients with HIV disease. Indinavir sulfate (Crixivan), a protease inhibitor, is widely used to treat patients with HIV infections. Urinary lithiasis has been associated with the use of Indinavir. As with other renal calculi, ureteral stents, hydration, analgesics, and antispasmodics have provided favorable outcomes. Nonsteroidal-anti-inflammatory drugs (NSAID) should be avoided as they have been shown to result in deterioration of renal function. The formation of urinary lithiasis is a frequent complication of Indinavir therapy resulting in stones in 3-9% of patients. Hyperhydration and acidification of urine are usually successful. However, emergency drainage is usually required in 3% of cases. 20% of patients have been shown to have crystals in the urine. 8% of patients had urologic symptoms (3% had nephrolithiasis, 5% had crystalluria associated with dysuria/back pain). Crystalluria may be associated with dysuria and urinary frequency. Flank or back pain is associated with intrarenal sludging and the classic syndrome of renal colic. It is also believed that Crixivan stones may act as a nidus for heterogenous nucleation leading to the development of mixed urinary stones. Surgical intervention may be required in some patients. In addition, a combined medical and surgical intervention may be necessary. Indinavir therapy averaged 5.7 months prior to presentation of renal colic. All patients presented with microscopic hematuria. The median number of symptomatic urinary stone episodes after initiating Indinavir was 2 stones per patients. Radiographically, Indinavir stones are typically radiolucent. Abdominal CT scan demonstrated hydronephrosis without calcifications. CT scan with contrast may demonstrate the presence of crixivan stones. These stones can cause high grade ureteral obstruction. The radiolucent-gelatinous nature of such stones makes lithotripsy a poor choice of treatment.


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