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Polycythemia Vera

Hi, I am new to the forum having been diagnosed with PV in May 2017 . My treatment up till now has only consisted of Asprin, however following my last appointment my Haematologist wants me to have venesection .Does this mean the Asprin alone has not had the desired effect? I assume that further blood tests will determine if/when I will need further venesection, but I wonder how soon after the first venesection you would expect to see a positive reaction in eg Hematocrit concentration .

I appreciate that my haematologist, is the best person to answer such questions, but as usual was a bit overwhelmed at my last clinic appointment and it was only when I left that I considered these points .

I am due at haematology clinic next month, when I hope to be better prepared,

Meantime I only ask if any of the forum members have experience of this sort of treatment plan.

Kind regards,


8 Replies

Hi Paddy,

Your treatment sounds appropriate. My understanding is that most docs will start with aspirin and venesections. Asking for a venesection does not mean the aspirin is not having the desired effect - they serve different purposes. It likely means that your hematocrit is higher than it should be.

- The aspirin is to reduce clotting.

- The venesections are to lower your hematocrit (target of 45 for men and 42 for women). Research has shown that keeping hematocrit below those levels reduces the threat of clots. When you get a venesection, it removes iron from your system which helps slow down the production of new red blood cells. Your body uses iron from dead red blood cells for new cells, so the removal of a bag of blood removes iron and slows down the overall production of red blood cells. It takes a while to replace the iron from natural food sources.

- The hematocrit will drop immediately (once you re-hydrate). My understanding is that a venesection reduces hematocrit by 2 percent.

- As you have venesections, it is likely that other blood values like MEAN CELL VOLUME (MCV) and MEAN CELL HEMOGLOBIN (MCH) will change - your cells will get a bit smaller. This is the desired effect to reduce clotting and hematocrit. In some people, platelets will also rise a bit.

Good luck,



Hi Bryan, thanks for your prompt and informative response .

kind regards



Yes Paddy, I agree with Bryan. I had several venesections when I was first diagnosed with PV, 3 years ago and they immediately brought down my haematocrit (57 - 43). I take baby aspirin to prevent clotting. My platelets and white cells then began to increase so I was put on Hydrea as venesections only affect the red count. I now take 1 Hydrea 5 days a week which is keeping everything stable. I no longer have venesections.

I have a good haemotologist who I see every 8 -10 weeks and we always discuss treatment options after the latest blood test. So far, all is under control and I feel well.

Kind regards,



The same thing happened to me at the beginning of my treatment. I had both medication and venesections. They work differently so both were needed. A venesection would last about three months and then be repeated after a check up with the haematologist. Once my meds were at the right level, the venesections were stopped.

So it does sound perfectly normal - well normal in our world!!

Best wishes,



Thanks Sally,

Kind regards



Hi Paddy, I can see you have had some good replies to your query, so all I will add is the next time you go to see your haematologist, write down all your questions so you don't forget to ask something important. Good luck, Maz


Hi Maz, you're spot on You know what its like, you think you've understood everything the doctors have told you and then come home and realise you've more questions than answers ! Hopefully, I'll be better prepared for my next appointment .

Many thanks



I have had PV for about 12 years. My first two years were aspirin and a low iron diet. I would need a blood draw about every six months. for a year then every three months. My Doctor put me on Hydroxy urea two 500 mg on Mon, Wed, & Fri one on each of the other days. It was six years before I needed another Blood draw and that was after the Christmas Holidays. Hope this helps.


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