Iron deficiency anemia is an anemia caused by the lack of stored iron in the body, affecting the synthesis of hemoglobin. It is characterized by a lack of stainable iron in the bone marrow, liver, spleen, and other organ tissues, as well as decreased serum iron concentration, transferrin saturation, and ferritin levels, typically presenting as microcytic hypochromic anemia. Thus, iron deficiency anemia refers to a deficiency of iron. Iron is an essential trace element in the human body, involved in cellular functions and metabolic processes. The body has a strict regulatory mechanism for iron metabolism to ensure that iron levels are always maintained at a normal level, referred to as iron homeostasis. Iron homeostasis relies crucially on the balance between intestinal iron absorption and the body's iron requirements. Once this balance is disrupted, problems in iron distribution, absorption, transport, and storage may occur, leading to iron deficiency anemia.