A 57-year-old man presents following the passage of dark red urine one day ago. He had a similar episode two months ago, for which medical attention was not sought. He denies suprapubic pain, urinary urgency, frequency, or dysuria. No constitutional symptoms are present.

His medical history is significant for mild hypercholesterolemia, which is well controlled on atorvastatin 5 mg/day. He is not on any antiplatelet agents or anticoagulants. He is a heavy smoker, with a 30 pack-year history. He only drinks socially. He is retired now, after working as a storekeeper in a large private company for many years.

A complete blood count shows a hemoglobin of 14.2 g/dL. All other cell indices, including platelet counts are normal. A random capillary glucose, renal profile, liver profile, and coagulation profile are all normal.