In my internet search today I came across the terms, primary vs. secondary osteoporosis. Primary osteoporosis is defined as bone loss due to aging, with no specific cause. Secondary osteoporosis has a direct cause, for example, extended use of prednisone. Then, one author, Dr. Susan Brown of "Better Bones" challenged the distinction, proposing that all osteoporosis has a direct cause, beyond just aging. I think she is on to something. Here is a link to her blog post, "Rethinking Osteoporosis." What do you think? She lists many possible direct causes, under the categories of nutrition, lifestyle, medical conditions, and drugs.