What is osteopenia?

Osteopenia refers to bone mineral density (BMD) that is lower than normal peak BMD but not low enough to be classified as osteoporosis. Bone mineral density is a measurement of the level of minerals in the bones, which indicates how dense and strong they are. If your BMD is low compared to normal peak BMD, you are said to have osteopenia. Having osteopenia means there is a greater risk that, as time passes, you may develop BMD that is very low compared to normal, known as osteoporosis.

What causes osteopenia?

Bones naturally become thinner as people grow older because, beginning in middle age, existing bone cells are reabsorbed by the body faster than new bone is made. As this occurs, the bones lose minerals, heaviness (mass), and structure, making them weaker and increasing their risk of breaking. All people begin losing bone mass after they reach peak BMD at about 30 years of age. The thicker your bones are at about age 30, the longer it takes to develop osteopenia or osteoporosis.

Some people who have osteopenia may not have bone loss; they may just naturally have a lower bone density. Osteopenia may also be the result of a wide variety of other conditions, disease processes, or treatments. Women are far more likely to develop osteopenia and osteoporosis than men. This is because women have a lower peak BMD and because the loss of bone mass speeds up as hormonal changes take place at the time of menopause. In both men and women, the following factors can all contribute to osteopenia:

• Eating disorders or metabolism problems that do not allow the body to take in and use enough vitamins and minerals
• Chemotherapy, or medications such as steroids used to treat a number of conditions, including asthma
• Exposure to radiation

Having a family history of osteoporosis, being thin, being white or Asian, getting limited physical activity, smoking, regularly drinking cola drinks, and drinking excessive amounts of alcohol also increase the risk of osteopenia and, eventually, osteoporosis.

What are the symptoms of osteopenia?

Osteopenia has no symptoms. You notice no pain or change as the bone becomes thinner, although the risk of breaking a bone increases as the bone becomes less dense.

How is osteopenia diagnosed?

Osteopenia is diagnosed with a bone mineral density (BMD) test, usually done to see whether you have osteoporosis. The most accurate test of BMD is dual-energy X-ray absorptiometry (DEXA), although there are other methods. DEXA is a form of X-ray that can detect as little as 2% of bone loss per year. A standard X-ray is not useful in diagnosing osteopenia because it is not sensitive enough to detect small amounts of bone loss or minor changes in bone density. See the topic Osteoporosis for more information on BMD testing.