Hematology and Oncology Book

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Iron Deficiency Anemia

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  1. See also
    1. Microcytic Anemia
    2. Pediatric Anemia
  2. Epidemiology
    1. Most common cause of Microcytic Anemia
    2. Incidence
      1. Children: 4-7% under age 15 years
        1. Rare before age 6 months in term infants
        2. Rare until birth weight doubles in Preterm Infants
      2. Men: 2-3%
      3. Women (non-pregnant): 12% when menstruating
        1. Drops to 6-9% after Menopause
        2. Incidence is 19-22% if Black or Mexican-American
    3. References
      1. (2002) MMWR Morb Mortal Wkly Rep 51:897
  3. Causes
    1. Premenopausal women
      1. Excessive menstrual flow: 2 mg/day iron lost
      2. Dietary Iron absorption: 1.5 - 1.8 mg/day iron gained
      3. Each Pregnancy: 500 to 1000 mg iron lost
    2. Males and Postmenopausal women
      1. Colon Cancer until proven otherwise
      2. Gastrointestinal blood Loss
        1. Gastritis from NSAID use
        2. Peptic Ulcer Disease
      3. Partial gastrectomy
      4. Diverticulosis
      5. Gastrointestinal angiodysplasia
      6. Ulcerative Colitis
      7. Increased iron requirements
        1. Pregnancy (see above)
        2. Childhood
    3. Less common Causes
      1. Gastrointestinal parasites (e.g. Hookworms)
      2. Gastrointestinal blood loss in long distance Running
      3. Hereditary Hemorrhagic Telangiectasia
      4. Pulmonary hemosiderosis
  4. Symptoms and Signs
    1. See Pica
    2. See Anemia Signs
    3. Change in stool color (Melena or bright red blood)
    4. History of excessive menstrual flow (Menorrhagia)
    5. History of gastrointestinal blood loss
      1. Hemorrhoids
      2. Peptic Ulcer Disease
    6. Medication usage predisposing to GI Bleeding
      1. NSAIDs
      2. Aspirin
      3. Corticosteroids
    7. Associated findings
      1. Generalized Pruritus
      2. Glossitis
      3. Angular Cheilitis
      4. Fatigue
      5. Developmental delay in children
  5. Labs
    1. Complete Blood Count (CBC)
      1. See Hemoglobin Cutoffs for Anemia
      2. See Hematocrit Cutoffs for Anemia
      3. Mean Corpuscular Volume (MCV)
        1. General
          1. See MCV Cutoffs for Microcytic Anemia
          2. MCV cutoff varies by age and per reference
          3. MCV usually <75 in iron deficiency Anemia
        2. Normocytic Anemia (MCV 80 to 100 fl)
          1. Normocytic early in course of Anemia
        3. Microcytic Anemia (MCV <80 fl)
          1. Microcytosis follows Hemoglobin drop of 2 g/dl
      4. Red Cell Distribution Width (RDW)
        1. Precedes change in Mean Corpuscular Volume
      5. Mean Corpuscular Volume to Red Blood Cell Count ratio
        1. See Mentzer Index
        2. Ratio <13: Thalassemia
        3. Ratio >13: Iron deficiency Anemia, Hemoglobinopathy
    2. Iron Studies (in order of sensitivity)
      1. Serum Ferritin <45 ng/ml (usually <20 ng/ml)
        1. Falls before other indices
        2. Most sensitive for iron deficiency Anemia
        3. Falsely elevated as acute phase reactant
      2. Total Iron Binding Capacity (TIBC) rises
      3. Serum Iron
        1. Falls after Serum Ferritin
        2. Falls after Total Iron Binding Capacity (TIBC)
      4. Transferrin Saturation decreased (<5-9%)
        1. Serum Iron to Total Iron Binding Capacity
        2. Falls after Serum Ferritin
      5. Serum Transferrin receptor assay (new)
        1. Increased in Iron deficiency Anemia
        2. Normal in Anemia of Chronic Disease
    3. Other Screening Tests
      1. Erythrocyte Protoporphyrin level increased
        1. Similar timing as with Transferrin Saturation
    4. Reticulocyte Count or Reticulocyte Index
      1. Useful in categorization of Anemia type
      2. Does not assess degree of iron deficiency Anemia
    5. Images
      1. HemeoncAnemiaIronDeficiency.jpg
      2. HemeoncAnemiaIronDeficiencyOnTreatment.jpg
  6. Differential Diagnosis
    1. See Microcytic Anemia
    2. Thalassemia
  7. Management
    1. Identify a source of blood loss
      1. High correlation to Colon Cancer in older patients
        1. Beware adult men with iron deficiency Anemia
        2. Beware postmenopausal women iron deficiency Anemia
        3. Ioannou (2002) Am J Med 113:276
    2. Iron Supplementation
      1. Bone Marrow response limited to 20 mg/day iron
      2. Typical adult dosing
        1. Ferrous Sulfate 325 mg PO daily
      3. Anticipated response
        1. Hemoglobin increases 1 gram/dl every 2-3 weeks
        2. Iron stores normalize after Hemoglobin is corrected
          1. May require additional 4 months to normalize
        3. Example timeline
          1. Week 2: Reticulocytosis (<10%)
          2. Week 3: Increased Hemoglobin halfway to normal
          3. Week 8: Normal Hemoglobin
      4. Continue Ferrous Sulfate 325 mg PO qd for 4-6 months
    3. Evaluate failure to respond to Iron Supplementation
      1. Noncompliance
      2. Poor iron absorption due to concurrent medications
        1. Concurrent antacid use
      3. Continued excessive blood loss
      4. Consider Parenteral iron if true malabsorption
  8. Resources: Patient Education
    1. Information from your Family Doctor: Iron Deficiency
      1. http://www.familydoctor.org/healthfacts/009/
  9. References
    1. (1998) MMWR Morb Mortal Wkly Rep 47:1
      1. http://www.cdc.gov/mmwr/pdf/rr/rr4703.pdf
    2. Shine (1997) Am Fam Physician 55(7):2455

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