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Iron deficiency

Friday, August 29, 2025 08:47AM

Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key component of the hemoglobin protein, acting as a transport medium for electrons within the cells in the form of cytochromes, and facilitating oxygen enzyme reactions in various tissues. Too little iron can interfere with these vital functions and lead to morbidity and death.[1]

Total body iron averages approximately 3.8 g in men and 2.3 g in women. In blood plasma, iron is carried tightly bound to the protein transferrin. Several mechanisms control iron metabolism and safeguard against iron deficiency. The main regulatory mechanism is situated in the gastrointestinal tract. Most iron absorption occurs in the duodenum, the first section of the small intestine. Several dietary factors may affect iron absorption. Iron deficiency develops when iron loss is not sufficiently compensated by the intake of iron from the diet. When this state is uncorrected, it leads to iron-deficiency anemia, a common type of anemia.[1] Before anemia occurs, the medical condition of iron deficiency without anemia is called latent iron deficiency (LID).

Anemia is a condition characterized by inadequate red blood cells (erythrocytes) or hemoglobin. When the body lacks sufficient amounts of iron, the production of the protein hemoglobin is reduced. Hemoglobin binds to oxygen, enabling red blood cells to supply oxygenated blood throughout the body. Women of childbearing age,[2] children, and people with poor diet are most susceptible to the disease. A primary cause of iron deficiency in non-pregnant women is menstrual bleeding, which accounts for their comparatively higher risk than men.[3] Most cases of iron deficiency anemia are mild, alongside physical symptoms such as dizziness and shortness of breath, women with iron deficiency may also experience anxiety, depression, and restless leg syndrome.[3] If not treated can cause problems like an irregular heartbeat, pregnancy complications, and delayed growth in infants and children that could affect their cognitive development and their behavior.[4][5]

^[7] Symptoms of iron deficiency can occur even before the condition has progressed to iron deficiency anemia.

Symptoms of iron deficiency are not unique to iron deficiency (i.e. not pathognomonic). Iron is needed for many enzymes to function normally, so a wide range of symptoms may eventually emerge, either as the secondary result of the anemia or as other primary results of iron deficiency. Common symptoms of iron deficiency include:[8]

Less common symptoms of iron deficiency include:[8]

Continued iron deficiency may progress to anemia and progressive fatigue. Iron deficiency can also cause an elevated platelet count (thrombocytosis). Low iron levels in the blood may make some people ineligible to donate blood.

Signs and symptoms in children

Iron deficiency in children can progress slowly and the signs and symptoms may not be obvious. The most common symptom in children is appearing tired and pale.[13]

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