Iron deficiency anemia is a condition in which the body does not have enough iron to produce adequate hemoglobin, reducing the blood's ability to carry oxygen.
Iron deficiency anemia is the most common nutritional form of anemia. It can result from inadequate iron intake, impaired absorption, increased requirements or blood loss. Treatment requires replacing iron and identifying and addressing the reason for iron deficiency.
Iron is stored mainly in tissues such as the liver, spleen and bone marrow. Bone marrow uses iron to produce hemoglobin within developing red blood cells.
Iron deficiency develops when iron loss or requirements exceed iron intake and absorption for a prolonged period. As iron stores become depleted, hemoglobin production eventually falls and anemia develops.
Iron is required to make hemoglobin inside red blood cells. When iron stores become depleted, hemoglobin production falls and red blood cells may become smaller and contain less hemoglobin, reducing oxygen delivery.
Iron deficiency progresses from depleted iron stores to iron-restricted red blood cell production and eventually iron deficiency anemia. The anemia is often microcytic and hypochromic, although early disease may have a normal mean cell volume.
Iron deficiency may occur without anemia or progress to iron deficiency anemia. Clinicians may also describe the condition according to its cause, such as nutritional deficiency, chronic blood loss, impaired absorption or increased physiological requirements.
Fatigue or unusual tiredness
Weakness
Pale skin or pale inner eyelids
Shortness of breath during activity
Dizziness or light-headedness
Headache
Fast heartbeat or palpitations
Difficulty concentrating
Brittle or spoon-shaped nails
Craving ice or other non-food substances
Restless legs
Common causes include chronic blood loss, heavy menstrual bleeding, pregnancy-related increased requirements, inadequate dietary iron intake, gastrointestinal blood loss, impaired intestinal absorption and increased needs during growth.
Menstruation, especially heavy menstrual bleeding
Pregnancy
Infancy, childhood and adolescence
Low intake of iron-rich foods
Gastrointestinal disease or surgery affecting absorption
Chronic gastrointestinal bleeding
Frequent blood donation
Diagnosis generally includes complete blood count, hemoglobin, hematocrit, red-cell indices and iron studies such as ferritin, serum iron, transferrin or total iron-binding capacity and transferrin saturation. The cause of iron deficiency should also be investigated.
Pallor
Fast heart rate
Brittle or spoon-shaped nails
Smooth or inflamed tongue
Cracks at the corners of the mouth
Signs of chronic blood loss
Reduced exercise tolerance
Restless-leg symptoms
Complete blood count
Hemoglobin and hematocrit
Mean corpuscular volume
Serum ferritin
Serum iron
Transferrin or total iron-binding capacity
Transferrin saturation
Reticulocyte count when clinically indicated
Upper gastrointestinal endoscopy when gastrointestinal blood loss is suspected
Colonoscopy when lower gastrointestinal bleeding requires investigation
Pelvic ultrasound when a gynecological cause of heavy bleeding is suspected
Peripheral blood smear
Stool testing for occult blood when clinically indicated
Testing for malabsorption or celiac disease when appropriate
Gynecological assessment for heavy menstrual bleeding
Additional gastrointestinal evaluation for unexplained iron deficiency
Anemia of chronic inflammation
Thalassemia
Vitamin B12 deficiency anemia
Folate deficiency anemia
Other causes of blood loss
Chronic kidney disease-related anemia
Other microcytic anemias
Iron deficiency may progress from depleted iron stores to iron-restricted red blood cell production and finally iron deficiency anemia. Severity is assessed using hemoglobin and clinical status rather than a cancer-like staging system.
Staging or grading systems differ between diseases. The information here is educational and should be interpreted by a qualified healthcare professional in the context of the individual case.
Treatment usually involves oral iron replacement when appropriate and correction of the underlying cause. Intravenous iron may be used when oral iron is ineffective, not tolerated, poorly absorbed or when rapid replacement is clinically necessary. Severe cases may require urgent treatment and, in selected situations, blood transfusion.
Oral iron replacement
Intravenous iron for selected patients who cannot tolerate, absorb or adequately respond to oral iron
Treatment directed at the cause of chronic blood loss
Other medicines or therapies when an underlying condition requires them
Medicines listed here are for educational information only. Do not start, stop, or change a medicine without professional medical advice.
Untreated iron deficiency anemia can cause severe fatigue, impaired physical performance, cognitive effects, pregnancy complications, developmental problems in children and, when severe, cardiovascular strain.
Severe shortness of breath at rest
Chest pain
Fainting or near-fainting
Very rapid heartbeat with severe weakness
Heavy ongoing bleeding
Confusion or markedly reduced alertness
Rapid deterioration in a person with known severe anemia
If symptoms are severe, rapidly worsening, or life-threatening, seek emergency medical care immediately.
The outlook is generally good when the cause is identified and iron stores are replenished. Persistent or recurrent anemia requires reassessment for ongoing blood loss, impaired absorption or another underlying condition.
Survival statistics describe outcomes in groups of people and cannot predict exactly what will happen to one individual. Prognosis depends on factors such as cancer stage, tumor biology, treatment response, overall health, and follow-up.
Iron deficiency is one of the most common nutritional deficiencies worldwide. Risk is particularly high in growing children, menstruating adolescents and adults, pregnant people and populations with limited access to iron-rich foods or healthcare.
Adequate dietary iron, appropriate supplementation for high-risk groups, management of heavy menstrual bleeding and prompt evaluation of unexplained blood loss can help prevent iron deficiency anemia.
What is my hemoglobin level?
What are my ferritin and transferrin saturation results?
What is causing my iron deficiency?
Could I be losing blood from my stomach or intestines?
Could heavy menstrual bleeding be causing the anemia?
Should I take oral iron or intravenous iron?
When should my blood count and iron stores be rechecked?
How should I take my iron medicine?
Do I need testing for another cause of anemia?
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