Compare and contrast features of intravascular and extravascular hemolysis.

• Intravascular

  • From normal RBCs being damaged by mechanical injury, complement fixation, or exogenous toxins

  • See anemia, jaundice, increased LDH, decreased serum haptoglobin (which binds up the toxic free Hb…decreased serum haptoglobin is pretty specific for anemia), hemoglobinemia, hemoglobinuria, and hemosiderinuria

  • Free Hb and metHb will be seen in serum and urine when haptoglobin is depleted

• Extravascular

  • Occurs when RBCs are rendered “foreign” or become less deformable

  • RBC destruction occurs in the mononuclear phagocyte system (mostly spleen, some liver)

  • See anemia, jaundice, increased LDH, and normal to mildly decreased serum haptoglobin (since hemolysis is occurring outside of circulation, free Hb is not released in great amounts)

  • Hemoglobinemia or hemoglobinuria are absent or minimal

  • Splenomegaly may occur due to hypertrophy of the RES

Category: Medical Subject Notes , Pathology Notes