In briefAnemia affects many active patients, from young female recreational athletes to elite male competitors. The treatment may simply be iron supplementation, but the causes of iron-deficiency anemia are many, including poor nutrition, exercise-induced hemoglobinuria or hematuria, gastritis, hemorrhoids, peptic ulcer disease, angiodysplasia, and adenocarcinoma. Therefore, physicians need to do a thorough evaluation that includes a medical history, family medical history, drug history, physical exam, and referral to a gastroenterologist if necessary.