Iron Deficiency Anemia
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Contents |
Etiology
- blood losses from:
- gastrointestinal losses
- genitourinary losses
- menstrual bleeding
- iron loss with each menstrual period is about 20 g
- each unit of blood contains 250 mg of iron
- phlebotomy
- chronic hemoptysis
- hemodialysis
-
- high intestinal transit time
- celiac disease
- parasitic infection by hookworms
- pregnancy: iron loss is 500-1000 mg in pregnancy
- lactation
- idiopathic pulmonary hemosiderosis
- infants with unsupplemented milk
Pathology
- depletion of iron stores
- compromised iron delivery to sites of utilization
- iron-deficient erythropoiesis
Clinical-manifestations
- most patients asymptomatic
- symptoms are those common to all forms of anemia
- symptoms develop only when Hgb < 7 g/ dL if anemia is chronic unless coexistent pulmonary or cardiovascular disease
- pica
- skin & conjunctival pallor
- cheilosis, cheilitis
- glossitis
- brittle or "spoon nails" ( koilonychia)
- restless legs syndrome
- iron-deficiency may cause cognitive impairment/poor performance on standardized tests in children & adolescents even in the absence of anemia [3]
Laboratory
- red blood cell ( RBC) count
- < 5 X10E12/L in iron deficiency
- > 5 X10E12/L in thalassemia
- > 16 in iron deficiency
- < 16 in thalassemia
- decreased in iron-deficiency anemia
- may be normal (33% of patients)
- when iron stores are adequate
- mild iron deficiency anemia
- patients with liver disease
- combined iron & B12 or folate deficiency
- mean corpuscular hemoglobin is decreased
- platelet count is often elevated (may exceed 1,000,000/ uL early in disease)
- reticulocyte count: inappropriately low for degree of anemia
- peripheral smear
-
- decreased in iron-deficiency anemia
- decreased with compromised delivery of iron to sites of utilization (see pathology)
- low serum iron also occurs in:
- usually increased (> 300 ug/ dL) in iron-deficiency anemia
- largely reflects transferrin concentration
- increased with compromised delivery of iron to sites of utilization (see pathology)
- may be normal or low in:
- earliest marker of iron deficiency
- low serum ferritin (<12-15 ng/mL) indicates iron-deficiency
- ferritin is an acute-phase reaction, thus high or normal levels may mask iron-deficiency; ferritin is elevated in:
- serum ferritin > 100 ng/mL rules out iron deficiency even with inflammation [2]
- transferrin saturation
- measured by serum iron/ total-iron binding capacity ( TIBC)
- <9% is consistent with iron deficiency >15% is consistent with anemia of chronic disease 9-15% requires a bone marrow biopsy to distinguish iron deficiency from anemia of chronic disease
- decreased with compromised delivery of iron to sites of utilization (see pathology)
- serum transferrin receptor (not routine)
- fecal occult blood
- serum free erythrocyte protoporphyrin ( FEP) not routine
- increased in:
- iron deficiency
- anemia of chronic disease
- heavy metal exposure
- normal in:
- anti-gliadin antibodies if resistant to oral iron ( celiac disease)
- bone marrow biopsy (not routine)
- gold standard for diagnosis of iron deficiency
- decreased absent stainable iron indicates iron deficiency
- adequate iron stores in the bone marrow rule out iron deficiency unless the patient has recently received iron through supplementation or transfusion
Diagnostic-procedures
-
- suspicion of upper GI bleed
- telangiectasias ( hereditary hemorrhagic telangiectasias) [2]
- colonoscopy for positive fecal occult blood
Differential-diagnosis
- iron deficiency accounts for the majority of all hypochromic microcytic anemias
- thalassemia
- hemoglobinopathy
- anemia of chronic disease
- sideroblastic anemia
Management
- treat underlying cause of iron deficiency
- transfusion if indicated
- symptomatic
- risk of damage to vital organ
- iron supplementation (see iron replacement therapy)
- parenteral iron ( iron sucrose)
- reserved for patients not candidates for oral therapy
- iron dextran ( imferon), iron sucrose
- ferric gluconate for dialysis patients
- four 200-mg infusions of iron sucrose over 2-weeks may reduce fatigue in women with low serum ferritin (< 15 ng/mL) but without anemia [6]
- rarely anaphylaxis will occur with parenteral iron
- maximal reticulocyte response occurs in 7-10 days of initiation of iron supplementation
- hemoglobin should normalize within 2 months
- continue iron for 3-4 months after normalization of hemoglobin to replenish iron stores
- Follow-up: 6-8 weeks to assess response to therapy.
More General Terms
Additional Terms
References
- Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 575
- Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15 American College of Physicians, Philadelphia 1998, 2006, 2009
- Prescriber's Letter 8(8):46, 2001
- Schiller G, UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
- Kagansky RE et al Are we giving too much iron? Low-dose iron therapy is effective in octogenarians. Am J Med 118(10):1142, 2005 PMID: [1]
- Krayenbuehl P-A et al. Intravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentration. Blood 2011 Sep 22; 118:3222. PMID: [2]
- National Guideline Clearinghouse
- Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). American Academy of Pediatrics ngc-guideline: [3]
