Thursday, April 16, 2009

Oh Schist!(....ocyte)

Microangiopathic Hemolytic Anemia (MAHA):

It is important to rule out the microangiopathic hemolytic anemia's when you see a CBC with anemia and thrombocytopenia. After a very detailed history and physical exam, a few additional tests must be done to clinch the diagnosis:
  • Hemolyitic work up: LDH, unconjugated bilirubin, haptoglobin
  • Coomb's test: to assess for autoimmune hemolytic anemia
  • Blood film: looking for schistocytes
If there your patient has biochemical evidence of hemolysis and schistocytes on the blood film then this is likely MAHA. Note that a positive Coomb's test in autoimmune hemolysis will typically be associated with spherocytes on the blood film - this is not MAHA

What are some of the more important causes of MAHA?
  1. Thrombotic Thrombocytopenia Purpura: presents with a classic pentad of fever, neurologic changes, renal failure, hemolytic anemia, and thrombocytopenia....although most patients have only 2-3 of these features. A great case-based approach to TTP can be found here.
  2. Hemolytic Uremic Syndrome: on the same spectrum as TTP, more common in children, and as the name implies it has a renal failure phenotype. Here is a cool paper from JAMA looking at the risk of developing HUS after treating E. coli 0157:H7 strains.
  3. Disseminated Intravascular Coagulation: check for coagulopathy with an INR, PTT, fibrinogen, and fibrin degradation products.
  4. HELLP Syndrome: a variant of pre-eclampsia with hemolysis, elevated liver enzymes, and low platelets. Read more about this here.
  5. Malignant Hypertension. More on this here.

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