A Rare Cause of Acute Kidney Injury: Crystal Nephropathy

Crystal nephropathy is defined as acute kidney injury (AKI) caused by the intratubular precipitation of crystals, which results in obstruction. We report here two cases of AKI associated with crystal nephropathy. The first case was a 69-year-old man. He had hematuria, proteinuria and renal failure. The second case was a 60-year-old woman. Her urine analysis was normal, but the serum creatinine level was high. Both of them had a history of nonsteroidal anti-inflammatory drug (NSAID) usage. AKI was considered in both cases. Because of the unimproved and progressively worsening renal function, renal biopsy was done in both cases and the diagnosis was crystal nephropathy. Renal biopsy is particularly helpful in cases with unexplained or prolonged AKI. AKI due to intratubular crystal precipitation is observed in association with many medications including NSAIDs, and a detailed history of drug usage is therefore important in cases with AKI.