Approach to hematuria (pediatrics) Quiz: Ace Your Exams

An 8-year-old boy presents to the pediatrician, accompanied by his parent, for hematuria that started that morning. There is no abdominal pain, dysuria, urinary frequency, urgency, or foul odor in the urine. The patient had a recent upper respiratory tract infection which self-resolved. He has no significant past medical history. A school hearing test done last week revealed bilateral high-frequency hearing loss. The child’s parent has a history of chronic microscopic hematuria. Temperature is 37.0°C (98.6°F), pulse is 82/min, respiratory rate is 20/min and blood pressure is 100/60 mmHg. The child is pleasant and in no distress. The bilateral ear canals and tympanic membranes are within normal limits and there are no abnormalities of the pharynx. Cardiopulmonary examination is unremarkable. Abdomen is soft, non-tender, and without masses, and there is no CVA tenderness. Gross blood is noted on the initial urine sample and microscopic hematuria with dysmorphic red blood cells persists on two subsequent tests each performed one week apart. Which of the following tests is most likely to establish the diagnosis in this patient?