Loss of bone mineral density (BMD) that is not severe enough to be considered osteoporosis is referred to as osteopenia. The term comes from the Latin osteo (bone) and the Greek penia (poverty).
In osteopenia, as in osteoporosis, bone formation is inadequate to compensate for normal bone loss. Osteopenia is more common in women than in men, typically occurs in people age 50 and over, and osteopenia is considered a risk factor for osteoporosis as well as for fractures.
Diagnosing Osteopenia
The same tests that check for osteoporosis are used to diagnose osteopenia. The gold standard for measuring bone mineral density for osteopenia, however, is dual-energy x-ray absorptiometry (DEXA or DXA). This test yields two results: a Z-score and a T-score. The Z-score is a person’s BMD relative to other people of the same age and sex; the more commonly used T-score represents a person’s score compared with that of a healthy 30-year-old of the same sex.
The difference between a person’s actual BMD and the expected BMD is expressed as a standard deviation (SD). A negative number means that a person’s bones are less dense than the ideal; the lower the number, the greater the bone loss. A T-score of –1.0 to –2.5 means that a person has osteopenia; a T-score of –2.5 or lower indicates osteoporosis. In general, every 1 SD reflects a 10% to 12% decline in BMD and is associated with a doubling in fracture risk.
Who’s at Risk for Fractures From Osteopenia And Osteoporosis?
Studies have shown that more than 50% of fractures in postmenopausal women occur in those who have osteopenia rather than osteoporosis. In fact, a study in the Archives of Internal Medicine found that out of more than 2,000 women who experienced a fracture in the previous 12 months, only 18% had osteoporosis. The remaining 82% had T-scores of –2.5 or better, and 67% had T-scores of greater than –2.0.
Although women with osteoporosis may be more likely to have a fracture, many more women are in the osteopenic range, which accounts for the higher number of fractures in this group.
A second large study published in the same issue of the Archives of Internal Medicine found that previous fracture risk—not T-score—was the strongest predictor of a future fracture in women with osteopenia. Researchers found that 4.1% of women with previous fracture experienced another within a year, compared with 2.2% of women with a
T-score of –1.8 or less.
In addition, women with osteopenia and a previous fracture had nearly the same risk of fracture as women with osteoporosis in other studies, reinforcing the idea that women with osteoporosis are not the only ones who should be targeted for fracture prevention.
For men, risk factors for osteopenia include excessive alcohol intake, low testosterone levels, and gastrointestinal problems (such as malabsorption or chronic diarrhea).
Treatment for Osteopenia
Treatment options for osteopenia (which are the same methods used for preventing osteoporosis) include weight-bearing exercise and calcium and vitamin D supplementation. These measures appear to be effective at maintaining or increasing BMD in women with osteopenia.
For example, a third study in same issue of the Archives of Internal Medicine found that 50 women with osteopenia who participated in an exercise program for 26 months had a BMD increase of 0.7% in the lumbar spine, compared with a 2.3% loss of BMD in a control group of 33 women who did not exercise.
Little is known about whether other osteoporosis treatments can also help women with osteopenia, since few studies have focused on this group. However, some trials have shown that medications such as bisphosphonates can help preserve or increase BMD in women with osteopenia.
There is no general consensus on the ideal BMD at which to start treatment for bone loss, but many doctors use a T-score of –2.5 or less (the definition of osteoporosis) as the threshold.
However, the National Osteoporosis Foundation recommends that osteoporosis treatment be initiated for anyone with a T score of –2.0 or less or with a T-score of –1.5 or less and at least one other risk factor for fractures (such as a prior fracture as an adult, a family history of fractures, low body weight [less than 127 lbs.] or cigarette smoking).
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