Exercise-related hematuria. Findings in a group of marathon runners.

Sequential urine specimens were obtained from 50 marathon runners before, immediately after, and on three successive days following a marathon race. All prerace samples were normal, but nine (18%) of the 50 postrace urinalyses showed gross (one specimen) or microscopic (eight specimens) hematuria. No formed elements other than RBCs were seen, and all abnormalities cleared by 48 hours. Exercise-related hematuria appears to be a frequent, self-limited, and benign condition. Physicians should be aware of its occurrence and reserve extended testing for cases in which abnormalities persist beyond 48 to 72 hours.