I was diagnosed with secondary polycythemia. My ENT and my hematologist both think that I don't get enough oxygen when I sleep despite my use of a CPAP machine. When I first was diagnosed, my primary care physician stopped my HRT because the testosterone could elevate red blood cell production. After several months he let me go back on at 2 mg/day instead of the previous 5 mg day. After 6 months of reduced HRT, I decided to supplement my dosage by other means. Oddly, for me, the testosterone increase has not affected my hematocrit which increases at the same rate without or without HRT.
I get bled (phlebotomy) about once a month so that my hematocrit is maintained at ~45. Since I polycythemia, my blood is thrown away instead of being used elsewhere. Wasting the blood is a shame since there's nothing wrong with it, i.e., I have no communicable diseases, and I don't have undesirable behaviors/habits that could endanger potential recipients.