Interesting thing I've noticed:
At work I've been using my own blood as a sorta kinda control/background test against a family with a genetic thrombocytopenia. I'm basically just using it to figure out how I'm going to set up an experiment.
Anyway, after I take my blood I spin it down to get the platelet rich plasma. Since getting back into training in the past 3 months, I've noticed a massive increase in my haematocrit. It's gone from roughly 40% to what looks like 60-70%. Is it a natural increase due to the effects of testosterone? anyway, it's pretty scarily high now...slightly worrying.