Anemia

Background

• Affects 1/3 of the world's population
• Most common causes are uterine and GI bleeding
• Pathophysiology
  • 4 mechanisms:
    • 1. Loss of RBCs by hemorrhage (e.g. GI bleed)
    • 2. Increased destruction (SCD, hemolytic anemia)
    • 3. Impaired production (iron/folate/B12 deficiency, aplastic/myelodysplastic anemia)
    • 4. Dilutional (rapid IVF infusion)

Clinical Features

• Most pts begin to be symptomatic at ~7gm/dL
• Weakness, fatigue, lethargy, DOE, palpitations
• Skin, nail bed, mucosal pallor
• Widened pulse pressure
• Jaundice, hepatosplenomegaly (hemolysis)
• Peripheral neuropathy (B12 deficiency)

DDX

1. Hemorrhage
2. Destruction (hemolytic)
   1. Hereditary
   2. Acquired
3. Impaired Production
   1. Hypochromic (microcytic)
      1. Iron deficiency, anemia chronic disease, thalassemia, sideroblastic anemia
   2. Aplastic/myelodysplastic (normocytic)
      1. Marrow failure, chemicals (ETOH), radiation, infection (HIV, parvo), RF
   3. Megaloblastic (macrocytic)
      1. Vit B12/folate deficiency, drugs (chemo), HIV

Diagnosis

• Microcytic Anemia (<81 fL)
  • RDW high
    • Ferritin low: Iron deficiency anemia
    • Ferritin normal: Anemia chronic disease or sideroblastic anemia (e.g. lead poisoning)
  • RDW normal
    • RBC count low: Anemia chronic disease, hypothyroidism, Vitamin C deficiency
    • RBC count nl or high: Thalassemia

• Normocytic Anemia ((81-100 fL)
  • Retic count nl
    • RDW normal: Anemia chronic disease, anemia of renal insufficiency
    • RDW high: Iron, Vit B12, or folate deficiency
  • Retic count high
    • Coombs Positive: Autoimmune cause
    • Coombs negative: G6PD, SCD, spherocytosis, microangiopathic hemolysis

• Macrocytic Anemia (MCV>100 fL)
  • RDW high: Vit B12 or folate deficiency
  • RDW nl: ETOH abuse, liver disease, hypothyroidism, drug induced, myelodysplasia

Treatment

• Transfusions
  • Consider if pt is symptomatic, hemodynamically unstable, hypoxic, or acidotic
  • Most pts w/ Hb <6 will benefit from transfusion; most pts w/ Hb >10 will not
  • Always draw labs necessary for diagnosis prior to transfusing
  • 1 unit PRBCs should raise the Hgb by 1gm/dL

See Also

Transfusions

Source

Tintinalli