A bone-density test is a way to measure the strength of your bones and the test it uses is called a DEXA scan, a type of X-ray. Every year, many people get a bone-density test. The main reason to have the test is to prevent fractures and disability and to treat serious bone loss, called osteoporosis. Most women under age 65 and men under 70 probably do not need the test because: - Most people do not have serious bone loss. - Most people have no bone loss at all or may only have mild bone loss (called osteopenia). - They do not need the test because they have a low risk of breaking a bone. - The best way to prevent bone loss is by exercising regularly and getting plenty of calcium and vitamin D.