09 Extrinsic Hemolysis

AIHA

  • antibodies coat RBC. RBC removed in spleen
  • RBC protect themselves from complement activation: no intravascular hemolysis

Warm

Pathogenesis and Symptoms

  • classic symptoms of anemia
  • splenomegaly: macrophages hypertrophy to consume RBCs

Diagnosis

  • smaller, spherical, lack central pallor
  • macrophage can't engulf whole RBC, just takes a bite off of it: shrink in size, more dense
  • also inherited disease

  • first see if normocytic anemia, then if RC is increased (increased production), then DAT

  • anti IgG antibodies bind to IgG on RBC and cause them to agglutinate

  • not used for AIHA
  • take patient serum and add sample RBC. Positive if antibodies in patient serum to RBC

  • used for new born hemolytic disease with mother serum against D+ RBC

Causes

  • all these diseases involve immune system

  • RBC bind antibody in absence of drug: surface of RBC altered

  • also cephalosporin

Treatment

  • severe: splenectomy

Cold

  • symptoms of anemia plus symptoms in extremities

  • large antibodies, cause RBC to agglutinate, especially in extremities
  • IgM fix complement, leaves bound C3 on RBC
  • DAT positive not for IgG but only for C3

  • C3 doesn't get in the way of macrophages like IgG: engulf whole
  • intravascular hemolysis result of complement activation

  • instead of add IgG, add anti-C3

  • IgG cold association with syphilis

MAHA

  • intravascular hemolysis
  • schistocytes: arrow, look like fragments

Mechanical

  • very high BP causes endothelial damage
  • thrombus shear RBC

  • narrow openings, stiff tissues

Infections

  • either intravascular RBC rupture or removal by spleen

  • sickle: Higher risk of severe disease in sickle cell disease
  • hole in robin's shirt: Higher risk of severe disease in asplenia
  • cracked blood stained windows: Hemolytic anemia
  • yellow babe: Jaundice
  • Sweating robin: fever
  • torn robin shirt: Irregularly cycling fevers