Anemia

Differential Diagnosis

Microcytic anemia (MCV <80)

• Iron-deficiency anemia
• Thalassemia
• Anemia of chronic inflammation (ferritin < 100 and transferrin saturation < 20%)
• Lead poisoning
• Sideroblastic anemia

Normocytic anemia (MCV 80-100)

• Elevated reticulocytes (normal marrow response)
  • Hemolytic anemia
    • Intrinsic RBC defect
      • Hemoglobinopathy
      • Enzymopathy: G6PD deficiency
      • Membrane-cytoskeletal defects
        • Hereditary spherocytosis
        • Hereditary elliptocytosis
      • Paroxysmal nocturnal hemoglobinuria
    • Extracorpuscular
      • Microangiopathic hemolytic anemia
      • Drugs and toxins: oxygen, nitrates, chlorates, methylene blue, dapsone, cisplatin, arsine, copper, lead
      • Infections: malaria, HUS, Clostridium perfringens
      • Autoimmune hemolytic anemia
        • Cold and warm AIHA
• Low or inappropriately normal reticulocytes (poor marrow response or low erythropoietin)
  • Chronic kidney disease

Macrocytic anemia (MCV >100)

• Megaloblastic
• Non-megaloblastic

Investigations

• CBC with differential
  • MCHC increased in HS and Hb SS
  • MCH decreased in hypochromic anemias
  • RDW increased in iron deficiency, reticulocytosis, blood transfusion
• Reticulocyte count (normally 1-2%)
• Peripheral blood film
• Ferritin, transferrin saturation
• Vitamin B12
• SPEP, and UPEP or serum free light chains