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NBME 23 Answers

nbme23/Block 4/Question#24

A 60-year-old man comes to the physician because of ...


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 +11  upvote downvote
submitted by thomasalterman(76),

Patient has polycythemia vera, as evidenced by erythrocytosis, granulocytosis, and headaches & diziness. EPO is decreased due to erythrocytosis. Decreased LAP would indicate CML, not PV.

btl_nyc  I thought this was CML. What am I missing that would say CML over PV? +2  
btl_nyc  Nvm, RBCs go down in CML, but everything goes up in PV. +4  

 +2  upvote downvote
submitted by guillo12(18),

"PV is a neoplastic (clonal) blood disorder with autonomous (EPO-independent) erythroid proliferation. Because of the existence of a negative feedback mechanism, the erthrocytosis in PV down-regulates EPO production and results in below normal serum EPO levels. In contrast, an EPO-driven erythrocytosis characterizes secondary erythrocytosis, and this condition may be associated with either high or normal serum EPO levels."


 +0  upvote downvote
submitted by runnerman92(0),

Increased Levels of Myeloid cells ( Erythrocytosis, thrombocythemia, and granulocytosis) plus Dizziness and Headache increase the suspicion for Polycythemia vera.

Low EPO in PV due to Negative feedback on EPO release by kidney.

dentist  This is where the timing of everything in the question trips me up. FA say PV mechanism is increase EPO (2019, p299) +