@garyr443 my ET is caused by the same mutation-CALR 9- that you have. My doctor said I was born with it. It just activated when I hit 73. Mutations are weird like that! I started with 1000mgs HU once a day. That was in April. My platelets dropped like a stone! They are now at 256 from 867. My red blood cells have also dropped big time. My white are just hovering above the “too low” level. My CNP lowered my dose to 500mgs once a day, but last blood test showed the platelets still at 256 and a continued fall of my red blood cells. I have an appointment soon and will see what the doctor thinks. I was utterly exhausted before the HU was lowered. The skin under my nails is dark grey to black. I wear nail polish to cover that up! I still feel tired each day, but it isn’t so bad now. I never nap! I eat like I always have and exercise a lot. Everyone is different, so you kind of have to decide what your goal is and how to reach it. You probably don’t want to have a stroke or heart attack from a clot, so that should weigh in as you decide your path forward. There are other drugs besides HU. ET is not well researched yet, so the older drugs used to treat the condition successfully are the ones the doctors like to prescribe. Still, all the feedback on these treatments has to come from us, the patients. So, speak up else how will our doctors know what this is like! I speak up a lot!