When I was in my young 20s, I had a bone density test done. I was osteopenic. He said it was probably from my months on prednisone as a teenager, which seemed crazy to me as I would have assumed after 7 years or so that the bone tissue would have grown back on it's own. He had me on calcium and vitamin D for months and rechecked me and I was back to normal. I've never been checked again and I'm now 35. Haven't really even thought about it til now.