MPN Voice
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Question about terms


I am from the USA and would like some clarification. I was diagnosed with PV due to elevated platelets and HCT and a positive JAC 2. I am currently managed by 500 mg of Hydroxyurea and baby aspirin, and have weaned down my therapeutic phlebotomies to one every three months. I notice that most people say they have ET with a positive JAC 2. How do you distinguish between ET and PV? Or is PV not a common term.

Thank you

4 Replies

Hi tsperl,

There are 3 main types of MPN. ET essential thrombocythaemia, PV Polycythaemia Vera, and MF mylofibrosis. Most are either jac2 + or - . Jac 2 is one mutation along with cal r. There is a full explanation of all the MPN's on

The site is also a mine of information and well worth reading.

I have PV Jac+ with high platelets also, so a PV with a bit of ET.

Best wishes


1 like

Hi my lovely! I believe it's to do with the white & red blood cells, one produces too many of one I think ET is too many white and PV has too many red! I have ET AND PV and am JAK2+


Hello tsperl, as Judy has advised, you will find all the answers on our website

Best wishes, Maz


I highly recommend visiting the site already mentioned. It's a great terminology resource. My understanding (as someone who has PV), is that ET involves mostly the platelets, whereas PV involves platelets AND hematocrit. I had been diagnosed with ET (elevated platelets) until my hematocrit started climbing.


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