Hemolytic Anemias

Definition

Hb < 12 g/dL (F) or < 13 g/dL (M) typically associated with elevated reticulocyte count and positive hemolytic markers, including:

Differential diagnosis

Immune:
- Autoimmune:
  - Warm autoimmune hemolytic anemia
  - Cold autoimmune hemolytic anemia (cold agglutinin disease)
- Alloimmune:
  - Immediate transfusion reaction
  - Delayed transfusion reaction
Non-immune:
- Intracorpuscular:
  - Hemoglobinopathy:
    - Sickle cell disease
    - Thalassemia
  - Membranopathy:
    - Hereditary spherocytosis
    - Hereditary elliptocytosis
  - Enzymopathy:
    - G6PD deficiency
    - Pyruvate kinase deficiency
- Extracorpuscular:
  - Thrombotic microangiopathy
  - Valve hemolysis
  - March hemoglobinuria
  - Spur cell anemia
  - Zieve syndrome
  - Wilson disease
  - Infection
    - Babesiosis
    - Malaria
    - C. perfringens
  - Thermal injury
Other conditions associated with positive hemolytic markers:
- Resorbing hematoma
- HLH
- Pernicious anemia

Peripheral smear findings

Condition	Findings
Warm autoimmune hemolytic anemia	Size +/- Microcytosis Anisocytosis (from spherocytes + reticulocytes) Staining Hyperchromia (loss of central pallor) Increased polychromatophilic cells Shapes Spherocytes Inclusions Typically none
Cold agglutinin disease	Size Normal Staining Mostly normochromic Increased polychromatophilic cells Shapes Normal Inclusions Typically none Other: RBC agglutination
Sickle cell disease	Size Normal Staining Loss of central pallor in sickle forms Increased polychromatophilic cells Shapes Irreversibly sickled cells Boat cells Inclusions Nucleated RBCs Howell-Jolly bodies Basophilic stippling
Hereditary spherocytosis	Size +/- Microcytosis Anisocytosis (from spherocytes + reticulocytes) Staining Hyperchromia (loss of central pallor) Increased polychromatophilic cells Shapes Spherocytes Inclusions Typically none
Thrombotic microangiopathy	Size Typically normal Staining Normal central pallor Increased polychromatophilic cells Shapes Schistocytes Inclusions Typically none

Examples of peripheral smear findings

Additional TBP resources

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