Blood test abnormalities in runners.

Physicians are conditioned to interpret blood test results outside "normal" limits as being signs of disease. In endurance-trained athletes, such "abnormal" tests results may instead be indications of physical activity. Data from six runners are presented illustrating that anemia, liver disease, myocardial ischemia, or renal disease might erroneously be diagnosed unless the physician is aware of the exercise habits of the patient.