Low-dose steroids for superficial reasons?

Question

I'm a young guy with unreal metabolism, resulting in an ultra-slim appearance. I work out and run often, and I have an appropriate diet, but I still can't gain muscle, or even weight of any kind.

What I'm after is a more muscular build, not like a pro wrestler, but enough so that others can't easily see my clavicle bones when I take off my shirt. You know, something more like that of an average athletic guy my age (18).

Here's the question (finally):
Is there a low-dose steroid or some kind of hormone that I can get to help me achieve this?

Answer 1

you probably have a hyperthyroid condition I would seek a qualified thyroid specialists . here is a link in thyroid too much increases metabolism and hence reduces the maintenance of muscle tissue.
http://www.mesomorphosis.com/articles/gundill/thyroid-muscle-growth.htm#RTFToC7

Answer 2

Don't mess with hormones or steroids until you are over 21/22. Peroid!

Eat more, take creatine, and keep your protein intake high. Oh and eat more.