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Updated: Dec 29 2021

Autoimmune Hemolysis

Images
https://upload.medbullets.com/topic/120235/images/splenomegalyandsubcaphematomacormark.jpg
https://upload.medbullets.com/topic/120235/images/differential for anemia - moises d.jpg
https://upload.medbullets.com/topic/120235/images/hemolytic_anemia.jpg
  • Snapshot
    • A 60-year-old man presents to his primary care physician with complaints of fatigue. His family is concerned that he looks very orange. He sometimes experiences shortness of breath with physical exertion. A peripheral smear comes back with some spherocytes as well as some smudge cells. His direct Coombs test comes back positive with anti-C3 and anti-IgG.
  • Introduction
    • Extrinsic hemolytic anemia caused by antibodies
      • type II hypersensitivity
      • Characteristics
      • Warm Agglutinin (IgG)
      • Cold Agglutinin (IgM)
      • Temperature at which antibodies are most reactive to RBC
      • Body temperature
      • Lower temperatures (39.2°F)
      • Chronic vs acute
      • Chronic
      • Acute
      • Complement-mediated
      • Associated conditions
      • SLE (most common)
      • CLL
      •  Drugs (α-methyldopa and penicillin)
      • Mycoplasma pneumonia
      • Infectious mononucleosis (EBV)
      • Epidemiology
      • AIHA (most common)
      • More common in women
      • Mneumonic
      • Warm weather is GGGreat
      • Cold weather is for ice cream, yuMMM
  • Epidemiology
    • Peak incidence in 50s-80s
  • ETIOLOGY
    • Associated conditions
      • thrombocytopenia (combination of AIHA and thrombocytopenia = Evans syndrome)
      • other autoimmune diseases
  • Presentation
    • Symptoms
      • warm agglutinin disease
        • chronic hemolytic anemia
      • cold agglutinin disease
        • acrocyanosis (different from Raynaud's)
          • painful and blue toes/fingers in the cold
          • “colder” parts of the body
          • numbness
          • mottling
        • symptoms resolve upon warming that part of the body
        • acute hemolytic anemia
    • Physical exam
      • splenomegaly
      • jaundice
      • livedo reticularis
  • STUDIES
    • Two types of Coombs test
      • direct (direct antiglobulin test, DAT)
        • anti-IgG (Coombs reagent) added directly to patient's RBCs
        • if RBCs coated with Ig (like in warm agglutinin disease), RBCs agglutinate
        • RBC agglutination = + DAT
        • can also use anti-C3 Coombs reagent
      • indirect
        • normal RBCs added to patient sample
        • anti-IgG (Coombs reagent) is added to mixture
        • if mixture has RBCs coated with Ig, RBCs agglutinate
        • RBC agglutination = + indirect Coombs
      • direct and indirect tells us the same thing, but indirect will tell us that there's more antibodies
      • Characteristics
      • Warm Agglutinin (IgG)
      • Cold Agglutinin (IgM)
      • Direct Coombs test
      • + Direct Coombs test with anti-IgG Coombs reagent
      • + Direct Coombs test (DAT) with anti-C3 Coombs reagent
      • Indirect Coombs test
      • + Indirect Coombs test (tests for IgG autoantibodies)
      • - Indirect Coombs test
      • Other tests
      • RBCs spontaneously agglutinate
      • at room temperature
      • Most accurate test
      • Cold agglutinin titer
      • Complement level
      • Normal C3 and C4
      • ↓ C3 and C4
    • Peripheral blood smear
      • spherocytes (also seen in hereditary spherocytosis)
      • no fragments
        • RBC are destroyed in spleen or liver, not the vessels
    • Serology showing hemolytic anemia
      • ↑ LDH
      • ↑ indirect bilirubin
      • ↑ reticulocyte count
      • ↓ haptoglobin
    • Urinalysis
      • hemoglobinuria
      • hemosiderinuria
  • Differential
    • Cryoglobulinemia
    • Lymphoma
    • Raynaud's syndrome
    • HIT
    • Hereditary spherocytosis
  • Treatment
    • Prevention
      • for cold agglutinin disease
        • keep warm
    • Warm agglutinin
      • from best initial therapy to further steps in treatment ladder
        • glucocorticoids
        • IVIG
        • splenectomy
        • immunomodulators
          • rituximab
          • azathioprine
          • cyclosporine
    • Cold agglutinin
      • keep extremities warm
      • supportive therapy with folate
      • rituximab
      • plasmapheresis for those refractory to rituximab
      • other immunosuppressants
        • cyclosporine
        • cyclophosphamide
  • Complications
    • Warm agglutinin
      • lymphoproliferative disease
      • venous thromboembolism
    • Cold agglutinin
      • peripheral gangrene
      • lymphoma
  • Prognosis
    • Mortality rate 10%
    • For most patients, prognosis is good
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