Morning Report 12.4

This morning we had an excellent case presented by Dr. Arnold, involving a schema to work up hemolytic anemia. The patient ended up having autoimmune hemolytic anemia.

Here are a few quick teaching points from this morning;

  1. RDW (RBC distribution width)
    • Represents the size distribution
    • Is either normal (uniform population), or elevated (greater than normal variation)
    • Not highly specific or sensitive for ruling in/out any diseases
    • May be elevated due to vitamin or mineral deficiencies, or cases in which there are a population of microcytic cells due to hemolysis plus reticulocytosis
    • Obtaining a smear is ideal
  2. AIHA (autoimmune hemolytic anemia)
    1. Involves Abs binding to the RBC with complement activation and hemolysis
    2. Two categories; if reacting at body temperature this is warm autoimmune hemolytic anemia, if reacting less than body temperature this is cold agglutinin disease 
    3. The DAT (direct antiglobulin / coombs) is the test of choice, which looks for either IgG or C3 bound to the RBCs
    4. Progressive coating of the membrane by IgG, leads to uptake of the RBCs by the reticuloendothelial system.
    5. Treatment; steroids! If does not respond, then may need splenectomy and/or cytotoxic drugs ex rituximab and others
      1. Transfuse Hgb only if symptomatic / if bone marrow not responding
    6. Evaluation of Warm AIHA should include searching for other causes ex. SLE, CLL, and can be induced by medications (drug induced hemolytic anemia);
      1. Abs against normal erythrocyte antigens (due to cross-reactivity with Ags that are altered due to the drug); methyldopa, levodopa, procainamide
      2. Abs against antigenic drug-protein complex on cell surface; cephalosporins, penicillins, NSAIDs, quinine, INH



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