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 (2).
  • Older patients with suspected IDA should undergo endoscopy to evaluate for occult GI malignancy (3)[C].

Pediatric Considerations

  • Risks for IDA in children include low birth weight, history of prematurity, lead exposure, low income status, and immigrant status. Additionally, infants who drink cow’s milk before 12 months of age have a higher risk for IDA.
  • The U.S. Preventive Services Task Force (USPSTF) did not find sufficient evidence for screening low-risk infants; the Centers for Disease Control and Prevention (CDC) recommends screening high-risk infants at 6 to 12 months, and the 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 (4)[A].


  • Iron deficiency is the most common nutritional deficiency in the world (5),(6), and IDA is the most common cause of anemia (50%) (5).
  • Predominant age: all ages but especially toddlers and menstruating and pregnant women
  • Predominant sex: female
  • Predominant race: Mexican American and black females (5)
  • Common in both 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 (6)

  • Infants and children age <12 years: 4–7%
  • Men: 2–5%
  • Menstruating women: 30% (6)

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, cow’s milk <12 months) (1),(4)
  • Iron- and vitamin Crich diet for menstruating women
  • Iron 30 mg/day for asymptomatic pregnant women (4)

Commonly Associated Conditions

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

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