An elderly male who works as a car mechanic presents with 3 weeks of rash and 1 week of epistaxis and mucosal bleeding, found to have thrombocytopenia with plt 1 and anemia with hemoglobin of 7.4. He was initially treated for ITP (with the thought that his anemia was just 2/2 bleeding), but due to his persistent cytopenias and inappropriately low reticulocyte count, suspicion was high for a bone marrow process; he ultimately was diagnosed with AML.
Take-home points for thrombocytopenia from Brad Lewis:
1) Schistocytes on a smear are only helpful if you see them. If you don’t see them, you still can’t definitively rule out your MAHAs (DIC, TTP, etc) so interpret along with other labs (LDH, haptoglobin, bili) and the overall clinical picture
2) Pay attention to the rest of the smear, and ask heme to help interpret – even a rare myelocyte or blast or nucleated RBC is significant.
3) Get that reticulocyte count, AND trend it! Often the trend will help more than a single value.
Help! I never know how to interpret a reticulocyte count.
Remember this rough graph to help you estimate if a reticulocyte count is inappropriately low (i.e. not high enough given the degree of anemia)
Kaiser SF Internal Medicine Residency Blog 