Macrocytosis

[johnnyjumpups]

I am 68 year old female with ET, JAK2V617F. Diagnosed in Dec. 2022 with blood only, no BMB. I take a baby aspirin and 500 mg hydroxyurea 5 days a week. Along with that diagnosis, all kinds of wacky things come up in a category called "morphology." One is Macrocytosis. I asked at my appointment with my hematologist/oncologist (nurse practitioner) why I have that, and she said because of my et. I have googled it and what I am worried about is the consequences of "untreated" macrocytosis. Permanent damage to nervous system and neurologic complications. My doctor's office is not concerned with it, but of course, I worry about every little thing. I do not have b12 deficiency or alcoholism. I have read and been told that HU actually causes macrocytosis. Does anyone have any input for me on this? I sure would appreciate it! Thank you.

[EPguy]

You're correct on HU causing high MCV. This plot is my MCV before, during, and after HU. It took a couple months to normalize.

None of my specialists were concerned about this, as it is common and a sign you're actually taking the drug. MCH is another that went up on HU.

Do you have MCV results before you started HU? This would tell how much is the HU vs the ET.

MCV

[johnnyjumpups in reply to EPguy]

Thank you for replying! Yes, I looked back and my MCV was 105.8 before HU and is 115.8 now. So I guess it's both. What I am concerned with is what to do about it and the long term effect it will have on me, like the nervous system and neurological effects. Nothing can be done to get it to normal?

[EPguy in reply to johnnyjumpups]

You likely have seen sites like this:

mayoclinic.org/macrocytosis...

Relevant macrocytosis causes include "increased red blood cell production" and "An underlying bone marrow cancer called myelodysplastic syndrome" (MDS)

--

You're not seeing an MPN specialist, rather a nurse practitioner, is that right?

You note a lot of abnormal morphology results beyond macrocytosis. Details matter for this and there could be information an MPN specialist can properly interpret, for example to rule out MDS.

[johnnyjumpups in reply to EPguy]

Thank you again EPguy. I appreciate your input and will be attempting to see a specialist. Thank you.

[hunter5582]

Concur with EPguy that you need to see a MPN Specialist rather than a regular hematologist. MPNs are rare disorders and most doctors/nurses, including hematologists. have little experience with them.

Macrocytosis is caused by HU. It is an expected outcome that is used to monitor adherence to the medication. If MCV is elevated then you would also see other changes. Interpreting these results requires looking at all of the erythrocyte numbers. If there were alterations in your MCV or other erythrocyte numbers prior to starting HU, this does need to be reviewed.

Here is a list of MPN expert providers. mpnforum.com/tsr-the-list/

[johnnyjumpups in reply to hunter5582]

Thank you Hunter5582. I appreciate your input.

[Meatloaf9]

Hi, I am almost 75 with PV for 7 years (known). After starting HU (2021) my MCV and MCHC both elevated above normal. MPN specialist said that was expected and how they know you are taking the HU. Mine has been elevated ever since, always between about 100 and 104. Last reading about 104. MPN specialist says that is Ok and expected. I have had no know problems with HU so far that I know of. Best to you.

[johnnyjumpups in reply to Meatloaf9]

Thank you Meatloaf9. I appreciate your reply.