Iron is required for the synthesis of hemoglobin, a protein in red blood cells (RBCs). While iron is essential, excess iron can be harmful, and thus iron homeostasis is tightly regulated. Iron is absorbed through a complex biochemical pathway. In normal iron homeostasis, iron is absorbed from enterocytes and recycled from senescent red blood cells engulfed by macrophages. Iron circulates bound to transferrin and is delivered to the bone marrow for erythropoiesis. Hepcidin, produced by the liver, is the central regulator of iron homeostasis. While iron absorption can be increased and decreased as needed via homeostatic mechanisms, there is no physiologic mechanism in place to excrete excess body iron.