Normocytic Anemia

Aka: Normocytic Anemia, Anemia of Chronic Disease, Anemia of Inflammation, Anemia of Systemic Disease

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II. Pathophysiology

  1. Underlying mechanisms
    1. Inhibition of Renal Erythropoietin synthesis and release
    2. Decreased Bone Marrow responsiveness to Erythropoietin
    3. Macrophage iron sequestration
    4. Increased RBC destruction
  2. Timing
    1. Anemia in the Intensive Care Unit develops within days to weeks
    2. Other Anemia of Chronic Disease develops over a 1-2 month period
  3. Other Anemias may be concurrently present
    1. Folate Deficiency
    2. Iron Deficiency Anemia
  4. Strenuous physical exertion can cause Normocytic Anemia
    1. Plasma volume expands
    2. Red Blood Cell mass remains unchanged

III. Evaluation

  1. MCV
    1. High normal MCV: Evaluate as Macrocytic Anemia
      1. Serum Vitamin B12
      2. Serum Folate
      3. Thyroid Stimulating Hormone (TSH)
    2. Low normal MCV: Evaluate as Microcytic Anemia
      1. Serum Ferritin
  2. Reticulocyte Count
    1. High Reticulocyte Count causes
      1. Obtain Hemolysis labs
        1. Serum Bilirubin
        2. Lactate Dehydrogenase
        3. Haptoglobin
      2. Positive Hemolysis labs
        1. Autoimmune Hemolysis
        2. Hemoglobinopathy (Hereditary Spherocytosis)
        3. Membrane disorders
        4. Enzyme defects
      3. Negative Hemolysis labs
        1. Bleeding without Iron Deficiency
        2. Hypersplenism
        3. Anemia recovery
    2. Normal Reticulocyte Count (suggests Bone Marrow hypofunction)
      1. Medical disease
        1. Consider Renal Function tests, Liver Function Tests, TSH
        2. Consider Erythropoietin
      2. Inflammation
        1. See Anemia of Chronic Disease causes below
      3. Bone Marrow disorder
        1. Leukemia
        2. Myelofibrosis

IV. Causes: Anemia of Chronic Disease

  1. Chronic Inflammation
    1. Infection
    2. Connective Tissue Disease (e.g. Rheumatoid Arthritis)
    3. Malignancy (excluding direct blood loss from cancer)
  2. Chronic Renal Failure
  3. Endocrine Failure (e.g. Hypopituitarism, Hypothyroidism)
  4. Hepatic disease

V. Labs

  1. Complete Blood Count
    1. See Hemoglobin Cutoffs for Anemia
    2. See Hematocrit Cutoffs for Anemia
    3. Hemoglobin (7-11 g/dl) suggests moderate Anemia
    4. Mean Corpuscular Volume (MCV) normal (80 to 100 fl)
      1. MCV cutoff varies by age and per reference
  2. Iron Indices reduced
    1. Serum Iron reduced
    2. Total Iron Binding Capacity reduced
    3. Iron Saturation variably low or normal
    4. Serum Transferrin decreased
    5. Serum Ferritin
      1. Decreased if Iron Deficiency Anemia
      2. Serum Ferritin increases as an acute phase reactant, a marker of systemic inflammation
  3. Bone Marrow Aspiration

VI. Resources

  1. Information from your Family Doctor: Normocytic Anemia
    1. http://www.familydoctor.org/handouts/639.html

VII. References

  1. Marino (2014) The ICU Book, p. 351
  2. Brill (2000) Am Fam Physician 62(10):2255-63 [PubMed]
  3. Wang (2016) Am Fam Physician 93(4): 270-8 [PubMed]

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