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)

Diagnosis

• Microcytic Anemia
  • 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
  • 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
  • RDW high: Vit B12 or folate deficiency
  • RDW nl: ETOH abuse, liver disease, hypothyroidism, drug induced, myelodysplasia

Treatment

Hb <6 --> almost always transfuse

Hb >10 --> almost never transfuse

DDX

1. Hemorrhage
2. Destruction (hemolytic)
   1. Hereditary
   2. Acquired
3. Impaired Production
   1. Hypochromic (microcytic)
      1. Fe deff, chronic disease, thalassemias, sideroblastic
   2. Aplastic/myelodysplastic (normocytic)
      1. marrow failure, chemicals (ETOH), radiation, infection (HIV, parvo), RF
   3. Megaloblastic (macrocytic)
      1. vit B12/folate def, drugs (chemo), HIV

Source

1/26/06 DONALDSON (adapted from Tintinalli's)