Acute Ciprofloxacin-Induced Crystal Nephropathy with Granulomatous Interstitial Nephritis.

Crystal-induced acute kidney injury (AKI) is caused by the intratubular precipitation of crystals, which results in obstruction and kidney injury. Ciprofloxacin, a commonly used antibiotic, causes AKI secondary to immune-mediated interstitial injury. Rare mechanisms of ciprofloxacin-induced renal injury include crystalluria, rhabdomyolysis, and granulomatous interstitial nephritis. Clinical and experimental studies have suggested that crystalluria and crystal nephropathy due to ciprofloxacin occur in alkaline urine. Preexisting kidney function impairment, high dose of the medication, and advanced age predispose to this complication. We report a case of ciprofloxacin-induced crystal nephropathy and granulomatous interstitial nephritis in a young patient with no other predisposing factors. The patient responded to conservative treatment without the need for glucocorticoids.