Renal US findings in sulfadiazine-induced crystalluria.

The authors report two cases of sulfadiazine-induced obstructive nephropathy that were diagnosed with ultrasound (US). Renal US demonstrated layered clusters of echogenic shadowing material--presumed to be sulfa crystals--which cleared when the crystalluria resolved. The authors conclude that renal US is helpful in diagnosing sulfa calculi and subsequent obstructive nephropathy.