Resident Report 1/28 – Hemolysis

A special thank you to Dr. Lee Levitt for coming to morning report to participate in this interesting case!

Teaching Pearls:

  • Discrepancy of a low O2sat along with normal PaO2 is classically seen with methemoglobinemia.
    • Other causes include poor perfusion state such as vasoconstriction, hypothermia, or any other conditions that cause poor flow state.
    • Methemoglobin – Iron within hemoglobin exists as the oxidized state (+3), causing decreased affinity for oxygen binding.
  • Carboxyhemoglobin – when carbon monoxide binds to hemoglobin.
    • Hemoglobin has a very high affinity for CO compared to O2. Causes the oxygen dissociation curve to shift to the left, leading to decreased ability for O2 unloading.
    • Pulse oximetry cannot distinguish between carboxyhemoglobin and oxyhemoglobin.
  • Workup of anemia
    • Underproduction
    • Blood loss
    • Increased destruction (hemolysis)
  • Reticulocyte count – important to correct for degree of anemia and time of maturation.
    • High corrected reticulocyte index suggestive of blood loss or hemolysis.
    • Low corrected reticulocyte index suggestive of underproduction.
  • Hemolysis Labs
    • High LDH, low haptoglobin, indirect hyperbilirubinemia, Coombs test
  • Blood Smear
    • Schistocytes, helmet cells suggestive if microangiopathic hemolytic anemia.
    • Bite cells and Heinz bodies suggestive of G6PD deficiency.
    • Spherocytosis suggestive of either hereditary spherocytosis or autoimmune hemolytic anemia.
    • Sickle cells suggestive of sickle cell anemia
    • Target cells suggestive of liver disease (in particular obstructive liver disease), hemoglobinopathy, etc
  • Causes of Intrinsic hemolysis
    • RBC membrane defects
      • Example includes hereditary spherocytosis
    • Hemoglobinopathy
      • Examples include thalassemia, sickle cell disease, etc
    • Oxidation Problem
      • Most common example is G6PD deficiency.
  • G6PD Deficiency
    • Different variants of disease spectrum
    • X-linked disease – manifest in males
    • Hemolysis precipitated by acute insult, including infections or medications.
    • Medications associated with hemolysis include primaquine, dapsone, sulfa medications, etc.
    • Mediterranean variant associated with favism.
    • Negative G6PD test does not rule out G6PD deficiency in the setting of hemolysis.

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