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Pros and Cons of JAK2 testing

Posted by torcia @torcia, Oct 3, 2023

My doctor has given me conflicting opinions on whether or not JAK2 testing would advisable. My platelets have been high normal (394-399) since 2016. This year, they were 401. I discussed this with my doctor at my annual physical and he said he wouldn't recommend JAK2 testing because they wouldn't treat me at this platelet level and it could be detrimental to have on my medical record. The retest of platelets 2 weeks later was 404. Tests for inflammation and liver function were normal. CBC with white cell differentiation was also normal. He ordered the JAK2 testing without much explanation. I'm afraid to get this done because of what he said to me during our appointment. I'm concerned a positive JAK2 test might result in a premature diagnosis and prevent further testing/exploration of other possible problems. A negative result doesn't seem definitive either. I'm also concerned about cost and future insurance coverage. On the other hand, knowing either way about JAK2 might provide direction or something to look out for. I'm curious if others are glad they had this test or regret it? Does it make sense for someone whose platelets are only slightly over normal with no symptoms?

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jerrlin | @jerrlin | Oct 5, 2023

Get a second opinion. A lot is yet to be learned.

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eileen11108 | @eileen11108 | Oct 6, 2023

Normal platelets are 150 to 450 per LabCorp. Also, your other counts are normal. I would not be too concerned at this time.

My primary watched my platelets for years. When they jumped to 621 he sent me to a hematologist for evaluation, I have ET JAK2 and now on Hydroxyurea three days a week.

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1 reply
torcia | @torcia | Oct 6, 2023
In reply to @eileen11108 "Normal platelets are 150 to 450 per LabCorp. Also, your other counts are normal. I would..." + (show)
@eileen11108

Normal platelets are 150 to 450 per LabCorp. Also, your other counts are normal. I would not be too concerned at this time.

My primary watched my platelets for years. When they jumped to 621 he sent me to a hematologist for evaluation, I have ET JAK2 and now on Hydroxyurea three days a week.

Jump to this post

Thanks. It's helpful to hear your experience. Did your platelets stay stable over time and then spike up or did they gradually increase over time?

The upper limit of the reference range for the Kaiser lab is 400, so mine are slightly over normal. The other thing I've discovered in reading research articles online is that regardless of whether they fall in the normal range, a platelet count of 400 is probably at least two standard deviations beyond the mean of the general population. In other words, 98% or more people have lower platelet counts. The average platelet count for women of my age is around 260. Platelets that much higher than average are associated with a variety of negative outcomes. It's just really hard to know what to do with this information and what tests to ask for. I am hopefully getting a referral to hematologist. I'm starting to think that the JAK2 testing might be a good idea. If JAK2 is positive, then at least I have a reason for the high platelets. If it's negative, then maybe I push harder for other cancer screenings.

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1 reply
eileen11108 | @eileen11108 | Oct 6, 2023
In reply to @torcia "Thanks. It's helpful to hear your experience. Did your platelets stay stable over time and then..." + (show)
@torcia

Thanks. It's helpful to hear your experience. Did your platelets stay stable over time and then spike up or did they gradually increase over time?

The upper limit of the reference range for the Kaiser lab is 400, so mine are slightly over normal. The other thing I've discovered in reading research articles online is that regardless of whether they fall in the normal range, a platelet count of 400 is probably at least two standard deviations beyond the mean of the general population. In other words, 98% or more people have lower platelet counts. The average platelet count for women of my age is around 260. Platelets that much higher than average are associated with a variety of negative outcomes. It's just really hard to know what to do with this information and what tests to ask for. I am hopefully getting a referral to hematologist. I'm starting to think that the JAK2 testing might be a good idea. If JAK2 is positive, then at least I have a reason for the high platelets. If it's negative, then maybe I push harder for other cancer screenings.

Jump to this post

In June 2022 I was put on 500 mg Hydroxyurea every day. I started with headaches, dizziness, and a first ever vertigo attack. Hematologist took me off HU for a time and then put me back on 500 mg every other day. I did get down to 434. Eventually I had another break, now 500 mg only three days a week and headaches are less. Platelets are at 534 so next test will show how three days a week is working, All other labs are good.

By the way, my hematologist first said my goal was 450 or less and now she just said she would like me to get to below 400.

Good luck with your journey, Eileen

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1 reply
torcia | @torcia | Oct 7, 2023
In reply to @eileen11108 "In June 2022 I was put on 500 mg Hydroxyurea every day. I started with headaches,..." + (show)
@eileen11108

In June 2022 I was put on 500 mg Hydroxyurea every day. I started with headaches, dizziness, and a first ever vertigo attack. Hematologist took me off HU for a time and then put me back on 500 mg every other day. I did get down to 434. Eventually I had another break, now 500 mg only three days a week and headaches are less. Platelets are at 534 so next test will show how three days a week is working, All other labs are good.

By the way, my hematologist first said my goal was 450 or less and now she just said she would like me to get to below 400.

Good luck with your journey, Eileen

Jump to this post

Thanks for sharing your experience. I'm glad you've found a treatment that's tolerable and seems to be working.

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hlyonsrn | @hlyonsrn | Oct 7, 2023

I had platelets up to 600 and hemocrit top level to where they would take off some blood. When your platelets get higher if they do they will do a JAK2 test for sure. That and elevated platelets put you in a high risk of clotting and as for me before I was diagnosed had a blood clot the entire length of my left arm and with US they realized I had had another clot at some time in my brachial area. So due to that I'm high risk. Know if you are JAC 2 positive just gives them a better look at what preventative measures they need to take

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1 reply
torcia | @torcia | Oct 7, 2023
In reply to @hlyonsrn "I had platelets up to 600 and hemocrit top level to where they would take off..." + (show)
@hlyonsrn

I had platelets up to 600 and hemocrit top level to where they would take off some blood. When your platelets get higher if they do they will do a JAK2 test for sure. That and elevated platelets put you in a high risk of clotting and as for me before I was diagnosed had a blood clot the entire length of my left arm and with US they realized I had had another clot at some time in my brachial area. So due to that I'm high risk. Know if you are JAC 2 positive just gives them a better look at what preventative measures they need to take

Jump to this post

Thank you! Blood clots are scary. So glad they caught yours in time. I guess I should get the JAK2 so that I know what I'm dealing with. I want to get a TB test first. Apparently you can have latent TB that can increase platelets. Feels like a longshot, but something good to rule out before the more expensive JAK2 test.

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