Bone mineral density, or BMD, typically increases from birth until early adulthood, and begins to lessen thereafter. People with osteopenia, or low BMD, appear to have lost BMD and might be at risk of developing osteoporosis, a disease characterized by pronounced loss of BMD and increased risk of fractures. Eighty percent of osteoporosis cases are women, who typically reach their BMD peak at age 30.
Background
According to the National Osteoporosis Foundation, or NOF, osteopenia can be a warning signal for developing osteoporosis. Its clinical significance, however, cannot be determined without an assessment of other risk factors, such as drug side effects, other health conditions, and, perhaps, follow-up scans to see if BMD continues to decrease over time.
Diagnosis
Osteopenia is identified by a BMD scan, a method of measuring the amount of calcium and other minerals in your bones. According to NOF, BMD measurements are interpreted by comparisons with a standard maximum bone density, which for both men and women is early adulthood.
How your BMD differs from this maximum is measured in T-scores, statistical measures of how much your BMD is above or below the standard maximum. For osteopenia and osteoporosis, T-scores measure how much lower your BMD is than this average. According to World Health Organization, a T-score between +1 and -1 is considered within the normal range, a T-score between -1 and -2.5 indicates osteopenia, and a T-score of -2.5 or lower indicates osteoporosis. Only between 1 percent and 5 percent of the population have T-scores of -2.5 or below.
Significance
A BMD scan showing osteopenia does not necessarily signal that you will develop osteoporosis. According to the University of Washington's Radiology Department, although the most common cause of osteopenia is osteoporosis, other reasons exist for low BMD. You might have had inadequate dietary calcium and vitamin D to develop sufficient BMD to begin with. Toxic exposures, including a history of smoking, heavy alcohol use, or lead exposures might have decreased your BMD. Medications such as steroids or heparin might have decreased your BMD, and other medical conditions, including anemia, metabolic or endocrine conditions, including menopause, pregnancy, and diabetes, can erode BMD.
Consequences
Although not as severe as osteoporosis, osteopenia weakens bones, increasing fracture risk. The challenge is determining whether osteopenia is an early warning sign of osteoporosis or there is another reason for the low BMD.
In either case, according to researchers at Johns Hopkins Medicine, you should reduce exposures to toxic substances and behaviors, modify medications, and address other health conditions contributing to decreases in BMD. In addition, you should take calcium and vitamin D and increase your weight-bearing exercise.
Treatment
Whether to treat osteopenia with bone-building prescription drugs developed for osteoporosis is debatable. Researchers at Johns Hopkins Medicine caution that osteopenia is not a disease and given the side effects and expense of treatment, prescription drug therapy for osteopenia should not be done routinely. The Surgeon General's Report emphasizes osteopenia only indicates risk and other clinical factors should be assessed.
