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Iron deficiency anemia

Last updated: January 13, 2021

Summary

Iron deficiency anemia (IDA) is the most common form of anemia worldwide and can be due to inadequate intake, decreased absorption (e.g., atrophic gastritis, inflammatory bowel disease), increased demand (e.g., during pregnancy), or increased loss (e.g., gastrointestinal bleeding, menorrhagia) of iron. Prolonged deficiency depletes the iron stores in the body, resulting in decreased erythropoiesis and anemia. Symptoms are nonspecific and include fatigue, pallor, lethargy, hair loss, brittle nails, and pica. Diagnostic lab values include low hemoglobin, microcytic, hypochromic red blood cells on peripheral smear, and low ferritin and iron levels. Once diagnosed, the underlying cause should be determined. Patients at risk for underlying gastrointestinal malignancy should also undergo a colonoscopy. Iron deficiency anemia is treated with oral (most common) or parenteral iron supplementation. Severe anemia or those with concomitant cardiac conditions may also require blood transfusions. The underlying cause of IDA should also be corrected.

Epidemiology

  • Most common form of anemia worldwide [1]
  • ∼ 3% of the general population in the United States is affected [2]
  • Ethnic variations: African-American and Mexican-American populations in the US are at increased risk.
  • Prevalence highest in: [3]
    • Children up to 5 years of age
    • Young women of child-bearing age (due to menstrual blood loss)
    • Pregnant women

Epidemiological data refers to the US, unless otherwise specified.

Etiology

The most common causes of IDA can be divided by age groups and pathophysiologic mechanisms.

Based on age [1][4]

In resource-limited countries, adults > 50 years that present with IDA should have colon polyps/carcinoma ruled out as a potential underlying etiology.

Based on underlying mechanism [4][6][7]

Pathophysiology

Clinical features

DICEd Plumm - Dysphagia, Iron deficiency anemia, Carcinoma of the esophagus, Esophageal webs in Plummer-Vinson syndrome.

References:[2][11]

Diagnostics

Approach

Laboratory tests [12]

Low ferritin and iron levels in combination with an elevated TIBC are diagnostic of iron deficiency anemia.

Increased ferritin does not rule out iron deficiency anemia. It can be increased in response to simultaneous inflammation.

Evaluation for underlying cause [1][12]

Treatment

References:[2][17]

Differential diagnoses

See "Diagnostics" in “Anemia.”

Iron deficiency anemia Anemia of chronic disease
Ferritin Normal to
Iron normal to ↓
Transferrin/TIBC Slightly ↓
Transferrin saturation Normal to slightly ↓
RDW normal
Soluble transferrin receptor (sTfR) normal

References:[2][12]

The differential diagnoses listed here are not exhaustive.

Special patient groups

Iron deficiency anemia in pregnancy

  • Epidemiology
    • > 40% of pregnant women are iron deficient [18]
    • Second most common cause of anemia in pregnant women (after physiologic anemia)
  • Etiology: increased iron requirements
  • Treatment: oral or IV iron supplementation (see “Treatment” above) [19][20]
  • Complications
    • Increased risk of adverse pregnancy outcomes
    • Impaired fetal neurodevelopment

References

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  2. Intermittent iron and folic acid supplementation during pregnancy in malaria-endemic areas. https://www.who.int/elena/titles/intermittent_iron_pregnancy_malaria/en/. Updated: February 11, 2019. Accessed: November 6, 2020.
  3. Lactation CoNSDPa, Medicine Io. Nutrition During Pregnancy. National Academies Press ; 1990
  4. Markova V, Hansen R, Thomsen LL, Pinborg A, Moos T, Holm C. Intravenous iron isomaltoside versus oral iron supplementation for treatment of iron deficiency in pregnancy: protocol for a randomised, comparative, open-label trial.. Trials. 2020; 21 (1): p.742. doi: 10.1186/s13063-020-04637-z . | Open in Read by QxMD
  5. Short MW, Domagalski JE. Iron deficiency anemia: evaluation and management.. Am Fam Physician. 2013; 87 (2): p.98-104.
  6. Killip S, Bennett JM, Chambers MD. Iron deficiency anemia. Am Fam Physician. 2007; 75 (5): p.671-678.
  7. Laura Percy, Diana Mansour. Iron deficiency and iron-deficiency anaemia in women's health. The Obstetrician & Gynaecologist. 2017; 19 (2): p.155-161. doi: 10.1111/tog.12368 . | Open in Read by QxMD
  8. Camaschella C. Iron-Deficiency Anemia. N Engl J Med. 2015; 372 (19): p.1832-1843. doi: 10.1056/nejmra1401038 . | Open in Read by QxMD
  9. Kazal LA Jr. Prevention of iron deficiency in infants and toddlers.. Am Fam Physician. 2002; 66 (7): p.1217-24.
  10. Institute of Medicine (US) Committee on Use of Dietary Reference Intakes in Nutrition Labeling. Dietary Reference Intakes, Guiding Principles for Nutrition Labeling and Fortification. National Academies Press ; 2003
  11. Anderson GJ, McLaren GD. Iron Physiology and Pathophysiology in Humans. Springer Science & Business Media ; 2012
  12. Sostres C, Gargallo CJ, Lanas A. Nonsteroidal anti-inflammatory drugs and upper and lower gastrointestinal mucosal damage. Arthritis Res Ther. 2013; 15 (Suppl 3): p.S3. doi: 10.1186/ar4175 . | Open in Read by QxMD
  13. Angular Cheilitis. http://research.omicsgroup.org/index.php/Angular_cheilitis. Updated: February 28, 2017. Accessed: February 28, 2017.
  14. Novacek G. Plummer-Vinson syndrome. Orphanet J Rare Dis. 2006; 1 (36). doi: 10.1186/1750-1172-1-36 . | Open in Read by QxMD
  15. Khan Y, Tisman G. Pica in iron deficiency: a case series. J Med Case Reports. 2010; 4 : p.86. doi: 10.1186/1752-1947-4-86 . | Open in Read by QxMD
  16. Bermejo F, García-López S. A guide to diagnosis of iron deficiency and iron deficiency anemia in digestive diseases. World J Gastroenterol. 2009; 15 (37): p.4638-4643.
  17. Mhadgut H, Galadima H, Tahhan HR. Thrombocytosis in Iron Deficiency Anemia. Blood. 2018; 132 (Supplement 1): p.4985-4985. doi: 10.1182/blood-2018-99-119352 . | Open in Read by QxMD
  18. Dan K. Thrombocytosis in iron deficiency anemia.. Intern Med. 2005; 44 (10): p.1025-6. doi: 10.2169/internalmedicine.44.1025 . | Open in Read by QxMD
  19. Xue CE, Shen QH, Wang Y, Zhang JY, Lin FR. [Clinical Significance of the Serum EPO Level in Patients with Iron Deficiency Anemia].. Zhongguo shi yan xue ye xue za zhi. 2015; 23 (5): p.1410-4. doi: 10.7534/j.issn.1009-2137.2015.05.036 . | Open in Read by QxMD
  20. Wei K-Y, Yan Q, Tang B, et al. Hookworm infection: a neglected cause of overt obscure gastrointestinal bleeding. Korean J Parasitol. 2017; 55 (4): p.391-398. doi: 10.3347/kjp.2017.55.4.391 . | Open in Read by QxMD
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  24. Soe-Lin S, Apte SS, Andriopoulos B Jr. Nramp1 promotes efficient macrophage recycling of iron following erythrophagocytosis in vivo. Proc Natl Acad Sci U S A. 2009; 106 (14): p.5960-5965. doi: 10.1073/pnas.0900808106 . | Open in Read by QxMD
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  26. Koilonychia.