Anemia, Iron Deficiency



  • Low serum iron associated with low hemoglobin (Hgb) or microcytic, hypochromic red blood cells (RBCs)
  • Because normal Hgb varies with age and sex, anemia is defined as Hgb level 2 standard deviations below normal for age and sex (1).
  • Onset acute (rapid blood loss) or chronic (slow blood loss, deficient iron intake, or poor absorption)
  • Both low Hgb per RBC and fewer RBC in total lead to blood oxygen deficiency, which can have serious systemic consequences
  • System(s) affected: hematologic, lymphatic, immunologic, cardiac, and gastrointestinal (GI) systems

Geriatric Considerations

  • Iron deficiency anemia (IDA) is associated with increased hospitalization, morbidity, and mortality in older adults.
  • Older patients with suspected IDA should undergo endoscopy to evaluate for occult GI malignancy.

Pediatric Considerations

  • Risks for IDA in children include low birth weight, history of prematurity, lead exposure, low-income status, immigrant status, and drinking cow’s milk before 12 months of age.
  • The U.S. Preventive Services Task Force (USPSTF) did not find sufficient evidence for screening low-risk infants; the Centers for Disease Control (CDC) recommends screening high-risk infants at 6 to 12 months of age, and the American Academy of Pediatrics (AAP) recommends universal screening at 12 months (1).
  • Should screening be done, include both Hgb and ferritin.

Pregnancy Considerations

  • The USPSTF did not find sufficient evidence for screening pregnant women for IDA; the CDC recommends screening women for anemia at the first prenatal visit and giving low-dose iron to all pregnant women, whereas the American College of Obstetricians and Gynecologists (ACOG) recommends screening all pregnant women for IDA and treating those with IDA.
  • Iron supplements are recommended during pregnancy to improve maternal hematologic indexes, although significant clinical outcomes have not been proven (2)[A].


  • Iron deficiency is the most common nutritional deficiency in the world, and IDA is the most common cause of anemia (50%).
  • Predominant age: all ages but especially toddlers and menstruating and pregnant women
  • Predominant sex: female
  • Common in developing and developed countries


  • Adults: men 2%, women 15–20% annually
  • Infants and toddlers: 3–5% annually
  • Pregnant patients: may be as high as 20% (1)

2 billion people worldwide

  • Infants and children aged <12 years: 4–7%
  • Men: 2–5%
  • Menstruating women: 30%

Etiology and Pathophysiology

Depletion of iron stores leads to decrease in both reticulocyte count and production of Hgb. Causes:

  • Blood loss (menses, GI bleeding, trauma)
  • Poor iron intake
  • Poor iron absorption (e.g., atrophic gastritis, postgastrectomy, celiac disease)
  • Increased demand for iron (e.g., infancy, adolescence, pregnancy, breastfeeding)

Risk Factors

  • Premenopausal woman
  • Frequent blood donor
  • Pregnancy/lactation, young maternal age
  • Strict vegan diet
  • Use of NSAIDs
  • Hospitalized with frequent blood draws
  • Living in or visiting countries with endemic hookworm infection

General Prevention

  • Consider screening asymptomatic pregnant women and high-risk children at 1 year of age (guidelines vary) (1)[C].
  • Supplementation in asymptomatic children aged 6 to 12 months if at risk for IDA (e.g., malnutrition, abuse) (1),(2)
  • Iron- and vitamin Crich diet for menstruating women
  • Iron 30 mg/day for asymptomatic pregnant women (2)

Commonly Associated Conditions

  • GI tract malignancy, peptic ulcer disease (PUD), Helicobacter pylori infection, irritable bowel disease
  • Hookworm or other parasitic infestations
  • Hyper metrorrhagia
  • Pregnancy
  • Obesity treated with gastric bypass surgery
  • Malnutrition
  • Medications such as NSAIDs or antacids

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