The most common cause of anemia is blood loss. This may be the result of bleeding related to disorders of the gastrointestinal tract, lungs, kidneys, and uterus, or of severe trauma with arterial bleeding from any site. During premenopausal years, menstrual blood loss is a common cause of anemia, particularly in women with limited dietary iron intake (e.g., from low red meat intake). Up to 25 percent of menstruating females have absent iron stores due to monthly iron loss. This chronic bleeding may result in impaired bone marrow production of RBCs, which then increases the degree of anemia already present.
Causes of anemia medical expert witness specialties include hematology, internal medicine, hospitalist medicine, pediatric hospitalist medicine, reproductive endocrinology, and pediatrics.