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A bone mineral density test is the best way to measure your bone health. It can tell you if you have osteoporosis and predict your risk for a bone fracture. If you are being treated for osteoporosis, a bone density test can tell your doctor how your bones are responding to treatment. [1-3]
Osteoporosis causes your bones to become thin, weak, and brittle. Osteoporosis is a common cause of fractures that can lead to disability. A fractured hip or wrist may be the first sign of osteoporosis. Osteoporosis is five times more common in women than men. The reason is the female hormone estrogen. Estrogen helps prevent bone loss in women. But when estrogen starts to drop around the time of menopause, there is a rapid loss of bone that lasts about three years. 
The most common bone density test is called a DEXA scan. This test is a painless imaging study that scans your bones while you lay still for several minutes. Radiation exposure from the test is less than a chest x-ray.  DXA usually measure bone density in your hip and lower spine. Other bone density tests measure density of your arm, wrist, finger, or heel. These tests can’t diagnose osteoporosis, but they can suggest the need for a DXA scan if they are abnormal. 
What Is a T-Score?
DXA reports your results as a T-score. Your bone density is compared to the normal bone density of a healthy young adult. Differences between your bone density and the normal density is measured in units called standard deviations: 
- A T-score of 0 means your score is the same as the healthy adult.
- A T-score 1 unit below normal (-1) is still considered within the normal range.
- A T-score between 1 and 2.5 units below normal (-1 to -2.5) is low bone mass, also called osteopenia.
- A T-score more than 2.5 units below normal (-2.5) means osteoporosis and an increased risk for bone fracture.
Who Should Get a DXA Scan?
DXA testing is recommended for all women age 65 and older. If you are postmenopausal, but under age 65, bone density testing may be recommended if you have risk factors for osteoporosis. These risk factors include: 
- A history of a bone fracture due to fragile bone
- A diagnosis of rheumatoid arthritis
- Body weight less than 127 pounds
- A history of smoking or alcohol abuse
- A history of hip fracture in a parent
If you have a normal DXA scan, you do not need to have another scan for up to 15 years. If you have an abnormal scan, your doctor may order testing more frequently to check for more bone loss. 
Do Men Need Bone Density Testing?
There is not enough evidence to recommend routine bone density testing in men.  Although osteoporosis is thought of as a woman’ disease, it can also occur in men, especially men over age 70. Just like women, the first sign in men may be a bone fracture of the hip, wrist, or spine. Men have larger and stronger bones than women and they do not have rapid bone loss like women do around menopause. However, by age 70 men are losing bone at the same rate as women. 
Bone density testing with DXA is the same for men as women, with the same T-score interpretation. Bone density testing for older men may be recommended if a physical exam shows that they are losing height or having a change in posture. A sudden fracture is another reason for treating. Testing is also done for men with these risk factors:
- Long-term disease of the kidneys, lungs, or stomach
- Use of steroid medication
- Signs of low testosterone
- Lack of physical activity
- Smoking or alcohol abuse 
How Is Osteopenia and Osteoporosis Treated in Men and Women?
If you have osteopenia, you may be able to prevent osteoporosis and a future fracture by increasing calcium and vitamin D in your diet. Calcium helps build bones and vitamin D helps you absorb calcium from your diet. You can also strengthen your bones with weight-bearing exercises like walking or jogging. 
Exercise helps because bone is living tissue that responds to exercise by adding more calcium. Recommendations for exercise are about 30 minutes on most days of the week. Weight-bearing exercise is any activity that that you do while standing, requiring your muscles and bones to work against gravity. 
Diet sources for calcium include leafy green vegetables, dairy foods, and canned fish with bones (like sardines). Vitamin D is not present in many foods so it is added to milk, juice, and cereal, fortified with vitamin D. To make vitamin D in your body, you need to be exposed to sunshine. Try to get outdoor sun exposure for about 15 minutes a few days each week. 
If you have osteoporosis, you should do all the same things you do for osteopenia, but your doctor may start you on a medication to treat osteoporosis.  Supplements for calcium and vitamin D may also be recommended by your doctor. 
RECOMMENDED FOR YOU
- Osteoporosis Guidelines: When Should I Get My First DEXA Scan?
- Exercises To Help Osteopenia and Osteoporosis
- 10 Tips to Fight Osteoporosis
- NIH, Bone Mass Measurement: What the Numbers Mean, https://www.bones.nih.gov/health-info/bone/bone-health/bone-mass-measure
- ACOG, Osteoporosis, https://www.acog.org/en/Womens%20Health/FAQs/Osteoporosis
- NIH, Osteoporosis in Men, https://www.bones.nih.gov/health-info/bone/osteoporosis/men