Autoimmune Hemolytic Anemia

Aka: Autoimmune Hemolytic Anemia, Autoimmune Hemolysis, Immune Hemolytic Anemia, AIHA, Warm Hemolysis, Cold Hemolysis, Cold Agglutinin Disease, Warm Agglutinin Disease, Warm Autoimmune Hemolytic Anemia, Cold Autoimmune Hemolytic Anemia

advertisement

II. Pathophysiology

  1. Autoantibodies bind Red Blood Cells results in RBC lysis (Hemolysis)

III. Type: Warm Antibody (IgG mediated, extravascular Hemolysis, more common)

  1. Mechanism
    1. IgG binds RBCs typically at Rh complex at 37 C (Body Temperature)
    2. Reticuloendothelial Macrophages ingest IgG-bound membrane
    3. Form microspherocytes which are trapped by Spleen (may result in Splenomegaly)
  2. Causes
    1. Idiopathic Hemolytic Anemia (most common)
    2. Non-Hodgkin's Lymphoma
    3. Chronic Lymphocytic Leukemia (CLL)
    4. Systemic Lupus Erythematosus (SLE)
    5. Human Immunodeficiency Virus (HIV)
    6. Drug Induced Immune-Mediated Hemolysis

IV. Type: Cold Antibody (IgM and complement mediated, intravascular Hemolysis)

  1. Mechanism
    1. IgM transiently binds RBCs at 32 C (cold)
    2. Activates complement and C3 binds RBC membrane at PolysaccharideAntigens
    3. C3 bound RBCs are lysed on rewarming and are cleared by the liver
  2. Causes
    1. Human Immunodeficiency Virus (HIV)
    2. Mycoplasma pneumonia or other infection
    3. Infectious Mononucleosis
    4. Lymphoma
    5. Idiopathic

V. Type: Paroxysmal (Cold Hemolysis mediated by IgG)

  1. See Paroxysmal Cold Hemoglobinuria
  2. Causes
    1. Tertiary Syphilis
    2. Acute Viral Infection (Mumps, Measles)

VI. Findings

  1. Fatigue on exertion
  2. Dark Urine
  3. Jaundice

VII. Labs

  1. Diagnostic findings
    1. Hemoglobin
      1. Severe, symptomatic Anemia unresponsive to pRBC transfusion
    2. Direct Antiglobulin Test (Direct Coombs) positive
  2. Other supportive findings
    1. Reticulocyte Count increased
    2. Lactate Dehydrogenase (LDH) increased
      1. LDH Is higher in Warm Hemolysis (intravascular)
    3. Indirect Serum Bilirubin increased
    4. Haptoglobin decreased

VIII. Management

  1. General
    1. Consult with Hematology
    2. Blood Product Transfusions
      1. Use caution if pRBC transfusion needed
      2. Identify least cross-reacting pRBC match
  2. Cold Hemolysis
    1. Avoid cold exposure
    2. Supportive management
  3. Warm Hemolysis
    1. Associated with a severe, fulminant course with mortality as high as 22%
    2. Immunosuppressants (response rates as high as 70 to 80%)
      1. Corticosteroids (e.g. Prednisone 1-1.5 mg/kg/day)
      2. Biologic Agents (e.g. Rituximab)
    3. Other measures
      1. Red Blood Cell Transfusion
        1. Indicated for Hemoglobin <7 g/dl (70 g/L)
        2. Warm pRBCs to normal Body Temperature to reduce the risk of Hemolysis by >50%
        3. Coordinate with blood bank when transfusing in Autoimmune Hemolytic Anemia
      2. Splenectomy
        1. Indicated in refractory Autoimmune Hemolytic Anemia
      3. Cyclophosphamide
      4. Intravenous Immunoglobulin (IV Ig)
      5. Plasma exchange
      6. Hematopoietic Stem Cell Transplant

IX. References

  1. Schreiber in Goldman (2000) Cecil Medicine, p. 876-82
  2. Dhaliwal (2004) Am Fam Physician 69:2599-606 [PubMed]
  3. Jones (2024) Am Fam Physician 110(1): 58-64 [PubMed]
  4. Petz (2001) Curr Opin Hematol 8(6):411-6 [PubMed]
  5. Phillips (2018) Am Fam Physician 98(6): 354-61 [PubMed]

Images: Related links to external sites (from Bing)

These images are a random sampling from a Bing search on the term "Autoimmune Hemolytic Anemia." Click on the image (or right click) to open the source website in a new browser window. Search Bing for all related images

Related Studies

Related Topics in Hemolytic Disorders

advertisement