Good morning, @sudutoo. I hope you have your reading glasses on! You have a lot of questions about essential thrombocythemia and thrombocytosis so I thought I’d drop a load of reading material out here for you.

Throughout my acute myeloid leukemia and bone marrow transplant journey 5 years ago, I became fascinated with blood cancers and blood conditions. I’ve learned first hand about the intricacies of our blood, bone marrow and immune systems, how mutations of genes work to mess with the order of things! We’re so incredibly complicated, it’s mind boggling that we even stay alive…just one little random mutation in the DNA and it can change the course of someone’s life.

You were diagnosed several years ago with thrombocytosis and wondering if this changes to ET.
In a large nutshell, Thrombocytosis occurs when another disease or condition causes you to have a high platelet count.

Thrombocythemia occurs when faulty cells in your bone marrow make too many platelets. Thrombocythemia is most often caused by your genes. Mutations or changes in the genes that control how your bone marrow forms platelets may cause thrombocythemia. Examples of such genes include JAK2, CALR, and MPL.

I believe you mentioned in one of your posts that you have a mutation in the JAK2 gene. That can be a key factor in the development of ET, PV (polycythemia vera) or MPF (myelofibrosis). Those are part of a group of blood conditions referred to as myeloproliferative neoplasms or disorders.

A good article from, verywellhealth.com explains the involvement of the mutated JAK2 gene in the potential development of these conditons:
https://www.verywellhealth.com/jak2-mutation-5217909
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Because of your elevated platelet count, your doctor suggested taking HU and that’s been successfully treating your condition since 2011. That sounds like a good track record! Sometimes we have to weigh the overall risk/reward benefit of taking meds that have potential side effects to keep us healthy and able to enjoy our lives to the fullest. While I’ve seen the reference to HU/leukemia link there seems to be no confirming evidence. Having an myeloproliferative disease has that remote, but underlying capability on its own without involvement of HU.

You might be interested in one of the articles in my list regarding HU and no evidence of it causing leukemia.
From The Hematologist by Ash Publications, Hydroxyurea's Leukemogenicity in Myeloproliferative Neoplasms: A Not Guilty Verdict https://ashpublications.org/thehematologist/article/doi/10.1182/hem.V8.6.1218/462498/Hydroxyurea-s-Leukemogenicity-in#

These last 5 articles all discuss thrombocytosis and essential thrombocythemia. I’m hoping by reading through these that you’ll better understand your blood condition of elevated white blood cells.

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https://www.mayoclinic.org/diseases-conditions/thrombocytosis/symptoms-causes/syc-20378315
https://www.healthline.com/health/primary-thrombocythemia
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https://www.verywellhealth.com/essential-thrombocythemia-2860907#:~:text=Essential%20thrombocythemia%20is%20a%20rare%20blood%20cancer%20that,potentially%20life-threatening%20complications%20like%20heart%20attack%20or%20stroke.
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https://www.medlink.com/handouts/essential-thrombocythemia#
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https://www.healthgrades.com/right-care/blood-conditions/essential-thrombocythemia
I know this is a long list for you to work through so take your time and take notes! Let me know if this was helpful for you!

I was diagnosed right away with Essential Thrombocythemia. (ET) having 1,250,000 platelets when first diagnosed. I had the Bone Marrow Biopsy and comfirmed JAK 2 so I guess if it is confirmed that gene mutation and no other disease caused it, it is ET. That is my understanding. But I could be wrong. Seems from what I have read that if another disease causes the over production of platelets, it might be possible to reverse it or stop the proliferation of the platelets, but with ET it is not curable, only treatable.