Primary renal hematuria presenting as unilateral gross hematuria

A patient with unilateral gross hematuria was found to have mesangial proliferation and IgM deposition on renal biopsy, consistent with the entity of primary renal hematuria. This case refutes previous assumptions that renal biopsy is normal in patients with unilateral hematuria. Glomerular lesions may be more common than previously suspected in the setting of unilateral hematuria. Renal biopsy can be useful both to define the natural history of unilateral hematuria and prevent repeated diagnostic procedures in patients with abnormal biopsies.