Benzbromarone as a possible cause of acute kidney injury in patients with urolithiasis: Two case reports

RATIONALE: Reports of acute kidney injury (AKI) associated with benzbromarone use in patients with hyperuricemia (HUA) are rare so far. PATIENT CONCERNS: We describe 2 unique clinical patterns in which benzbromarone was a possible cause of AKI following self-medication for HUA. In case 1, a 45-year-old man developed AKI after taking 100 mg of benzbromarone. His serum creatinine (Scr) increased to 2.3 mg/dL on day 2 after benzbromarone administration. Ultrasound showed multiple small stones in both kidneys, and the 24-hour urine uric acid level was 3128 mg. In case 2, a 17-year-old male student presented with AKI after self-administration of 50 mg of benzbromarone. His Scr increased to 6.8 mg/dL on day 3 after benzbromarone administration. Ultrasound showed multiple stones in the left kidney. DIAGNOSIS: Both patients underwent renal biopsy, with findings of acute tubular interstitial nephropathy in case 1 and acute tubular damage in case 2. Drug-induced AKI was considered. INTERVENTIONS: Both cases were treated supportively with intravenous hydration only. In both patients, the Scr level recovered within 0.5 months and renal function was normal 3 months after discharge. LESSONS: Oral benzbromarone is widely used in Asian counties to treat HUA and the adverse effects are mostly mild. However, clinicians should be alert for benzbromarone-induced AKI. Moreover, uricosuric drugs should only be used after exclusion of urolithiasis and other contraindications.