Atypical triad of IgA nephropathy: reversible acute kidney injury, gross hematuria, and severe bilateral flank pain.

Reversible acute kidney injury very rarely complicates the course of immunoglobulin A (IgA) nephropathy. We report an atypical case of reversible acute kidney injury, gross hematuria, and severe bilateral flank pain as the presenting triad of IgA nephropathy. Renal biopsy revealed mesangial IgA deposition without glomerular crescents. The patient's renal dysfunction, mediated by red cell tubular obstruction, interstitial nephritis, and tubular necrosis, resolved without intervention. We conclude that IgA nephropathy should be considered in the differential diagnosis for transient acute kidney injury with gross hematuria, and should be appropriately treated based on known prognostic factors.