Harvard Women's Health Watch

By the way, doctor: How often do I need a bone density test?

Q. I'm a healthy 65-year-old woman and just had my first bone density test. How often do I need to have it repeated?

A. Most doctors and organizations recommend that healthy women undergo bone mineral density (BMD) testing at age 65. There's good scientific evidence that BMD is linked to risk of fracture. The most widely used bone mineral density test is dual-energy x-ray absorptiometry, or DXA (see photograph).

How do I interpret my BMD?

The World Health Organization defines osteoporosis and osteopenia (bone density somewhat lower than normal) by calculating a woman's T-score, the number of standard deviations below the average value observed in healthy young adults. A T-score of –1.0 to –2.5 has been designated osteopenia. A T-score of –2.5 or lower indicates osteoporosis.

If you have osteoporosis, you should seriously consider countering bone breakdown with antiresorptive treatments, such as bisphosphonates, raloxifene, or nasal calcitonin. Estrogen (taken with a progestin in women who have an intact uterus) increases bone mineral density but is generally not prescribed for osteoporosis because of its serious risks — notably, heart disease, stroke, and breast cancer. Women with osteopenia may also want to consider treatment, depending on their other risk factors for fracture.

All postmenopausal women should take adequate calcium (1,200–1,500 mg/day) and vitamin D (current dietary guidelines suggest 400–600 IU/day of vitamin D, but recent evidence favors a higher daily intake, and many experts recommend 800–1,000 IU/day). It's also important to get regular weight-bearing and muscle-strengthening exercise.

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