20+ years ago my platelets were 1800.....out of the blue. No symptoms, annual checkup.Given Anagrelide (Agrylin then), 5 mg twice daily, did the job. Went from monthly, to quarterly to annual visits. Ten years later a new hemotologist (mine retired) did a very poor bone marrow biopsy (five painful attempts), switched me to HD, which threw all my blood off so I was seeing him weekly, had all kinds of other symptoms. Took me 8 weeks to get a DIFFERENT referral (oncology institue hematologist) who put me BACK on Anagrelide stating if it works why switch? So, if the aspirin is working, why switch? Doc likes my platelets to be below 450 so I try to make certain I'm taking meds as prescribed BEFORE blood work. Sometimes I forget in the evening and have mis-judged what I needed while traveling, didn't get back in rhythm before appointment. Oh, my. YES ET has not limited my life, thank God!

Ask the doc about this, but I can think of a couple of possible reasons:

1. You have the CALR mutation, and CALRs are less likely to clot. Docs sometimes let CALR patients run up to 700 or 800 before they want to give HU.

2. You are under 60 with no history of clots and are considered low risk.

Could be a combo of those things.

The old rule of thumb was that HU was good for 20 years and then it might begin to cause more serious side effects. It may be that newer studies on long-term effects of HU show that it's safe to take for longer periods, especially if doctors are giving the lowest effective dose. That might also be something to discuss with yr doctor.