The exact medical causes of osteoporosis are not completely known. However, many of the major factors that can lead to the disease have been identified, and are listed below:
Everyone loses bone with age. After age 35, the body builds less new bone to replace losses of old bone. In general, the older you are, the lower your total bone mass and the greater your risk for osteoporosis.
A family history of fractures; a small, slender body build; fair skin; and a Caucasian or Asian background can increase the risk for osteoporosis. Heredity also may help explain why some people develop osteoporosis early in life.
Nutrition and lifestyle
Poor nutrition, including a low calcium diet, low body weight and a sedentary lifestyle have been linked to osteoporosis, as have smoking and excessive alcohol use.
Medications and other illnesses
Osteoporosis has been linked to some medications, including steroids, and to other illnesses, including some thyroid problems.