Tell your doctor you are taking some OTC bodybuilding supplements of whatever and that you want to make sure they aren't unhealthy for you as you've heard some can be toxic. He should get the tests done.
There are some decent labs where you can get private blood work done. This avoids insurance issues and medical documentation of the tests. There are some online companies that do similar stuff. I'm sure someone here can list the one I'm talking about. I think it's San Francisco or Bay Area something or another, but I could be way off.