Hematuria, either macroscopic or microscopic, has a lengthy differential diagnosis. High on the list should be infection, cancer, and kidney stones. Don't, however, forget drug side effect as a cause. Many drugs can cause hematuria, including NSAIDs, some antibiotics (cephalosporins, Cipro, Rifampin, Bactrim), some diuretics (Lasix, Chlorothiazide), and some herbals (ginko biloba). This is just one more reason to go over the patient's med list thoroughly each visit.