I have a Humana PPO, and it's covered all my blood work so far, I only paid my $20 co-pay for the office visit right before I got the lab work across the hall in the same building. The testosterone was only $60 for a 5 month supply, so I didn't bother using insurance for that, especially since my prescription co-pays haven't been great in the past anyways. My doctor is a general practitioner though, so maybe they're not scrutinizing claims as much as they would with a specialist such as an endocrinologist.
I would assume that my doctor and her office's medical billing staff didn't bill it with some generic code or something, since my lab test orders that I took with me said the code number and then 'TRANSSEXUAL' next to each of the tests she wanted run. Maybe my plan does cover those things, I really have no idea since I work for a small company with no HR person and could never get a full copy of my benefits statement.