Hi Tom, There are quite a few members in the Connect forum who have been diagnosed with a Myeloproliferative disorder such as ET, PV or Myelofibrosis brought about with the involvement of a mutation in the JAK2 gene.
While the diagnosis can be similar not one size fits all when it comes to a treatment plan. Each person has their own case history which can have a bearing on types of treatment, dosages, when to treat, duration and all of those factors. Some people may have a higher risk for developing clots than others. So it’s really not a good idea to compare your own treatment plan with anyone else.

Not sure if you’ve been to visit this particular discussion.
Essential Thrombocythemia: Looking for information and support
https://connect.mayoclinic.org/discussion/essential-thrombocythemia-1/
Here are a few links to articles that I’ve found helpful to explain MPNs, diagnoses and treatments:
Verywellhealth.com
https://www.verywellhealth.com/myeloproliferative-disorders-5209654
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https://www.verywellhealth.com/jak2-mutation-5217909
I also want to caution you that those of us in the forum aren’t able to diagnosis or offer treatments for an illness but we are able to use our experiences to help out when we can. I’m sure other members with ET will be popping in to share their experiences with hydroxyurea, which is the front runner in helping to control excess platelets for someone with ET. But it can also temporarily lower all your blood product numbers including white and red cells. Your doctor will check to your numbers frequently and adjust your dosage accordingly. Some members have been able to decrease their dosage after the initial higher treatment helps drop the numbers to a preferred level/.

From my understanding it isn’t always necessary to have a bone marrow biopsy to diagnose ET. Blood work can suffice to check for levels and any possible genetic mutations. However, with any myeloproliferative disorder, there is a change in the production of your blood. That all begins in the bone marrow which is the blood manufacturing center of the body. So it’s not overkill to have test done. Your doctor is being thorough as this test will show the health of your bone marrow and its ability to continue to produce healthy blood and will serve as a baseline for any future changes.

You may not experience any noticable physical changes at all but because HU may lower your white blood cells, you may be more susceptible to infections or illness. So, don’t stop being active and engaging in your vital daily activities but just be a little mindful to avoid people who are ill, no raw sushi/oysters, wash hands frequently etc..

One more discussion for you about timing of HU. https://connect.mayoclinic.org/discussion/contolling-hydroxyurea-fatigue-by-time-of-day-you-take-the-medication/

When are you due for your next labs?