I started out having a phlebotomy every two weeks regardless of the numbers. This lasted about two months. Then we started doing them only when my hemoglobin hit or exceeded 17.0 . This lasted about a year and I only had 3 or 4 during that time. Since my numbers have stabilized pretty well, my doc said that he would let me know if he thought I should get one. Now the number that drives my dosage amount is my platelets count. That one seems to be the most volatile of the numbers that my doc keeps his eye on.