Anemia (iron-deficiency anemia)

Iron-deficiency anemia is the most common type of anemia worldwide. It develops when the body lacks enough iron to produce adequate hemoglobin, the protein in red blood cells that carries oxygen. As a result, tissues receive less oxygen, causing fatigue, weakness, and other symptoms.

Iron deficiency can result from blood loss, inadequate dietary iron, or impaired absorption. In adults, especially men and postmenopausal women, iron-deficiency anemia should prompt evaluation for a source of blood loss, including possible gastrointestinal disease. Treatment involves correcting the underlying cause and replacing iron stores with oral or, when needed, intravenous iron.

Mild iron deficiency may cause no symptoms. As anemia develops, common features include:

• Extreme fatigue and weakness
• Pale skin (including pale inner eyelids and nail beds)
• Chest pain, fast heartbeat, or shortness of breath, especially with activity
• Headache, dizziness, or lightheadedness
• Cold hands and feet
• Inflammation or soreness of the tongue
• Brittle nails or spoon-shaped nails (koilonychia)
• Unusual cravings for non-food items such as ice, dirt, or starch (pica)
• Poor appetite, especially in children
• Restless legs syndrome in some people

Iron-deficiency anemia results from:

• Blood loss — heavy menstrual bleeding; gastrointestinal bleeding (ulcers, cancers, polyps, angiodysplasia, regular NSAID use); repeated blood donation; trauma
• Inadequate dietary iron — diets low in heme iron; exclusive cow’s-milk feeding in infants
• Impaired absorption — celiac disease, gastric bypass or other GI surgery, Helicobacter pylori, autoimmune atrophic gastritis, inflammatory bowel disease
• Increased requirement — pregnancy, rapid growth in children and adolescents

Higher-risk groups include:

• Women with heavy menstrual periods
• Pregnant people
• Infants and children, especially with high milk intake and low iron-rich foods
• Vegetarians and vegans who do not plan iron sources carefully
• Frequent blood donors
• People with gastrointestinal disorders or prior GI surgery
• Regular users of aspirin or other NSAIDs
• Endurance athletes in some cases

Untreated iron-deficiency anemia can lead to:

• Heart problems — rapid or irregular heartbeat; in severe cases, heart failure
• Problems in pregnancy — premature birth, low birth weight
• Growth and developmental delays in children
• Increased susceptibility to infection
• Worsening of underlying heart or lung disease

Perhaps most importantly in adults, the bleeding source itself (for example, a colon cancer) may progress if not identified.

Prevention strategies include:

• Eating iron-rich foods (red meat, poultry, fish, beans, lentils, tofu, fortified cereals, dark leafy greens)
• Pairing non-heme iron with vitamin C to enhance absorption
• Avoiding tea or coffee with iron-rich meals if iron stores are low
• Appropriate iron supplementation in pregnancy as advised
• Screening high-risk infants and pregnant people
• Evaluating and treating causes of chronic blood loss

Laboratory evaluation typically shows:

• Low hemoglobin and hematocrit
• Low mean corpuscular volume (microcytic anemia)
• Low serum ferritin (most specific practical marker of iron stores)
• Low serum iron and transferrin saturation; elevated total iron-binding capacity
• Blood smear may show small, pale red cells

Once iron deficiency is confirmed, the cause must be pursued — especially in men, postmenopausal women, and premenopausal women without a clear menstrual explanation. This may include celiac testing, H. pylori testing, and bidirectional endoscopy (upper endoscopy and colonoscopy) as indicated by age and symptoms.

See a healthcare professional for persistent fatigue, pallor, shortness of breath, or other symptoms of anemia. Seek prompt care for chest pain, severe dizziness, or fainting. Adults with confirmed iron-deficiency anemia need evaluation for the cause, not only iron replacement.

Treatment has two goals: replace iron and correct the underlying cause.

Iron replacement

• Oral iron (ferrous sulfate, ferrous gluconate, ferrous fumarate, or newer formulations) — often taken every other day to improve absorption and reduce side effects
• Take on an empty stomach when tolerated; vitamin C may help absorption; avoid taking with calcium, tea, or antacids
• Intravenous iron when oral iron is not tolerated, not absorbed, or when rapid repletion is needed (e.g., ongoing blood loss, pregnancy in some cases, heart failure protocols)
• Red blood cell transfusion only for severe, symptomatic anemia or instability

Treat the cause — manage heavy menses, stop offending NSAIDs when possible, treat ulcers, eradicate H. pylori, manage celiac disease, or address gastrointestinal lesions as appropriate.

Hemoglobin typically rises within a few weeks; iron stores take longer to replete. Continue iron for several months after hemoglobin normalizes to rebuild stores, unless IV iron was given in a full repletion dose.

While recovering:

• Take iron supplements exactly as directed
• Expect darker stools; report severe constipation, severe abdominal pain, or vomiting
• Eat iron-rich foods and combine plant sources with vitamin C
• Limit tea and coffee around iron-containing meals or supplements
• Keep follow-up blood tests to confirm response
• Complete recommended evaluation for the source of iron loss

Bring:

• Description of symptoms and duration
• Menstrual history if applicable
• Diet pattern and any prior bariatric or intestinal surgery
• List of medicines (especially NSAIDs, anticoagulants, antacids)
• Previous blood-count results
• Questions about the cause of iron deficiency, type of iron replacement, and needed gastrointestinal evaluation