why does testosterone replacement therapy use different drug from steroids "abuse"?

cave_cat

what is the difference between testosterone and the anabolic steroids because of which the legit doctors prescribe testosterone and nonlegit "abuser" athletes inject steroids? Could doctors switch to steroids in equivalent doses with the same effect? Could athletes switch to testosterone if it were available from the dealer? Is there a fundamental difference between these hormone therapies or are they essentially the same and so the choice is driven by what is traditional or available to a given group?

cave_cat

ok, there is a perfunctory discussion of it here http://www.steroid.com/steroids_testosterone.php . It sounds like anabolic steroids have a function related primarily to muscle growth and, in fact, are used/"abused" in synergy with testosterone. So presumably they are not used in testosterone replacement since muscle growth is not the goal.