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When should I get a bone mineral density test?

Dr. Judith Reichman informs a menopausal woman on when's the best time to take her first bone density test and how osteoporosis can play a role.
/ Source: TODAY

Q: I have just become menopausal and my doctor says that according to current recommendations I should wait until I’m 65 to get my first bone density test. Isn’t that too late?

  • A: It might be. A bone mineral density test of the hip and spine is the gold standard for the detection of low bone mass. The U.S. Surgeon General, the American College of Obstetricians and Gynecologists, and the National Osteoporosis Foundation recommend that all women 65 years and older get a bone density test — but they also state that women who have any risk factors for a fracture should get the test at a younger age. At the time of menopause, especially if you’re not taking estrogen therapy, you’re at the greatest risk to lose bone mass (you can lose two to three percent per year for the first five to seven years of menopause). Obviously it’s extremely helpful to know “from whence you start”. I’m glad you’re asking this question now; fifty percent of peri menopausal and postmenopausal women don’t discuss osteoporosis with their physicians until they experience a fracture, which, although better than never, is too late.

Since there’s agreement that a woman should get a bone density test earlier if she has risk factors, let’s go over these factors. They are generally divided into two categories: major and less major. Here are the major risk factors:

  • You’ve already had a fracture in your adult years.
  • You’re thin (you weigh less than 127 pounds).
  • Your mother or sister has a history of osteoporosis and/or fragility fractures.
  • You’ve taken steroids in the past for three months or more.
  • You’re a long-term smoker or, worse, you currently smoke.

Here are the less major risk (but not to be ignored) factors:

  • You consume above moderate amounts of alcohol (more than two drinks a day).
  • You’ve gone through early menopause (before the age of 45) and/or you’ve had a lack of periods due to low estrogen for more than six months during your reproductive life.
  • You’ve had lifelong low calcium intake (you didn’t drink milk during your childhood and adolescent bone-forming years).
  • You lack physical activity. (If the muscle doesn’t pull on the bones, they lose mass).
  • You’re in general poor health and have a chronic disease.
  • You have balance and vision problems with a tendency to fall.

If you have any of these risk factors or (in my opinion) you intend to go through menopause without estrogen therapy, you should get a baseline bone density test. Often, you can get an inexpensive test that uses a portable ultrasound machine to test the density of the bone in the heel or arm. These tests give you and your doctor a “first look” at bone density, but they don’t tell you about the important areas of bone fragility (the hip and the spine).

The best way to get a number that reflects the bone mineral density  of these critical areas is with a  DEXA scan (dual-energy x-ray absorptiometry). It’s a simple noninvasive test: you lie on a table with your clothes on and in just 5 to 10 minutes an image of your bones will show up on a computer screen. Bone density is then calculated by the computer’s assessment of how much energy is absorbed by your bones.

The results of a bone density test are given in the form of the number of standard deviations (SD’s) from the bone density of an average 30-year old woman who has reached peak bone density. This is called the T-score. A comparison is also made with women in your same age group, and this is called the Z-score. A negative SD means there is bone loss. Minus or negative 1 SD translates into a bone loss of 10 to 15 percent below the average. The technical definition of osteoporosis is a T-score at or below -2.5 SD, whereas osteopenia (a fancy word for low bone mass) is a T-score of -1 to -2.5 SD.

These numbers are quite arbitrary, though, and the risk of osteoporosis can occur before that critical -2.5 T-score. For example, a study of almost 150,000 postmenopausal women showed that 82 percent of those with fractures had T-scores greater than –2.5, and 60 percent of these women had T-scores just over -2. Another study showed that 32 percent of women with a hip fracture and 54 percent with non-vertical fractures had a baseline bone mineral density of less than 2 SD below the average. In other words, they didn’t meat the “standard” for osteoporosis, but they had a fracture. I often see women in my practice whose T-score is between -1.5 and -2. I try to follow the National Osteoporosis Foundation's recommendation for these women, which says that pharmacological therapy (bisphosphonate drugs like Fosamax, Actonel, and Boniva) should be given to those who have a T-score of -1.5 and at least one risk factor. Some sort of therapy is also usually recommended for post-menopausal women whose T-score is more than -2. Regardless of their T-score, I tell all my patients to make sure they’re consuming (through food and supplements) adequate calcium (1,000 to 1,500 mg a day in divided doses, depending on age and bone status) and vitamin D (1,000 units IU daily).Dr. Reichman’s Bottom Line: Don't wait until the age of 65 to get a bone mineral density test if you have risk factors for osteoporosis. Earlier screening and appropriate therapy can mean the difference between bone health and bone fractures. Dr. Judith Reichman, the TODAY show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of .

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.