Anemia

Anemia

 

Anemia is characterized by decreased red blood cell mass, causing symptoms resulting from tissue hypoxia.

Definition (WHO)

  • Males – hemoglobin <13 g/dL (at sea level)
  • Females – hemoglobin <12 g/dL for nonpregnant females (at sea level)

Epidemiology

  • Incidence – 29-30/1,000 females; 6/1,000 males <45 years; 18.5/1,000 males >75 years
  • Age – different age peaks dependent on etiology of anemia
  • Sex – F>M during childbearing years

Classification

  • Based on morphology of red blood cell (rbc)
    • Mean cell volume (MCV)
      • Low MCV – microcytic
      • Normal MCV – normocytic
      • High MCV – macrocytic
    • Mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC)
      • Low MCH/MCHC – hypochromic
      • Normal MCH/MCHC – normochromic
  • Based on red blood cell production rate (measure of hemolysis)
  • Measured by reticulocyte count
  • Reticulocyte count formula (with correction for anemia):
    • Reticulocyte Count % (Hgb/Htc) (1/maturation time correction*)
      • *Maturation time correction is usually 2 for most patients

Pathophysiology

  • Macrocytic
    • Drug effect (hydroxyurea, azido-thymidine [AZT])
    • Nutrient deficiency – folate and/or B12
    • Hemolysis
    • Hypothyroidism
    • Excessive alcohol use
    • Myelodysplasia
  • Normocytic
    • Blood loss
    • Hemolysis
    • Renal insufficiency
    • Chronic disease (inflammatory or malignant)
    • Bone marrow infiltration
    • Hemoglobinopathies
  • Microcytic
    • Iron deficiency
    • Chronic disease (inflammatory or malignant) occurs in a minority of the cases
    • Thalassemia

Clinical Presentation

  • Acute loss – hypotension, tachycardia, confusion, diaphoresis
  • Chronic loss – fatigue, pallor, lack of stamina, breathlessness
    • Younger patients – may not have clinical symptoms until anemia is severe
    • Older patients – may first manifest with angina, dyspnea

Diagnosis

  • Laboratory testing
    • CBC with red blood cell indices combined with cell morphology on peripheral smear
    • Reticulocyte count
    • Further testing based on results of CBC and reticulocyte count
      • Total iron binding capacity (TIBC), serum iron, serum ferritin
      • Bone marrow biopsy may be needed

Treatment

  • Based on diagnosis
  • For acute loss – may require transfusion to maintain circulation

See Also