I was on a school field trip for my son's school and chatting with another parent who is an oncologist/hematologist. We were talking sleep apnea and he said that sleep apnea can cause a thickening of the blood. Basically, the body is starved of oxygen and produces more hemoglobin in an attempt to fuel the body better.
As many of you know, T therapy can cause this as well, and I've personally had to donate blood to address high hemoglobin. I had never heard of sleep apnea causing this, however, and thought I'd share with the group.
If you run into high hemoglobin a lot while on T therapy, you might want to consider a sleep study...