I didn't like varying my HU dosage from 500mgs to 1000mgs from day to day; I felt that I had more problems after taking the 1000mg dose. So I researched and found that HU is also made as Droxia (and marketed to sickle cell anemia pts). Droxia comes in 200, 300, &400mg doses, and my hematologist agreed to give me 600mgs/day of the Droxia. I've been on it for 6 yrs without difficulty. I'm 77, PMF, JAK2+, and have not had spenomegaly or anemia. Other blood counts are normal, except for LDH being double the normal range.