When Should I Get a Bone Density Test?

Bones, like many things in life, start to deteriorate in middle age.

At its most extreme, the deterioration has a clinical definition—osteoporosis—a diagnosis that translates to “porous bone.”

With osteoporosis, even a relatively benign activity—like wrestling open a sticky window—can break a bone. The consequences of such fractures late in life can be profound, including pain, decreased mobility and function, even decreased quality of life and increased mortality.

“In older age, a very high percentage of people—more women than men—have osteoporosis or low bone mass," says endocrinologist Marcella Donovan Walker, MD, professor of medicine at Columbia University Vagelos College of Physicians and Surgeons. “One in three women over the age of 50 will experience a fracture related to osteoporosis in their lifetime.”

Bone loss is, of course, invisible. To detect decreased bone mass in the skeleton before the first fracture occurs, clinicians rely on the non-invasive scanning technology known as DXA (short for dual-energy X-ray absorptiometry and pronounced “dexa”).

When to get a DXA scan?

Guidelines for when to get a bone mineral density scan, and how often to repeat the scan, vary.

Medicare generally covers DXA scans every other year for women over the age of 65 and men over the age of 70. Other medical organizations and the Bone Health and Osteoporosis Foundation recommend that scans can begin even earlier, as early as age 50, for women and men who have risk factors for fractures.

“Variability in the guidelines makes it really confusing for both patients and doctors,” says Walker, who assesses each patient’s risk to make personalized recommendations about when it’s time for a baseline DXA.

In women, bone mass drops most rapidly in the four to five years around menopause, when estrogen plummets, then slows and continues through the rest of life.

“Given that about 20% of women over age 50 have osteoporosis and 50% have low bone mass, getting a first scan around this age may be beneficial for people with risk factors,” says Walker, “because we have a chance to slow the loss before it gets worse.”

A wide variety of factors affect rate of bone loss, says Walker, whose own research investigates how certain medications speed or slow the process.

Osteoporosis risk is greater in people who take certain medications for cancer and epilepsy, blood thinners, and steroids. In all genders, a family history of osteoporosis, alcohol and tobacco use, and medical conditions including diabetes increases risk of fracture.

Based on your individual risk factors, your primary care provider can recommend when you should get your first DXA scan.

DXA is fast and painless

Like a regular X-ray, a DXA scan uses low-dose radiation, is fast and painless, and doesn’t involve any injections. Plan on 15 to 20 minutes for the procedure.

DXA measures how much of the X-ray passes through the bone and converts this to a density measurement. The lower the mineral content, the more the X-rays pass through the bone.

Results of the scan are sent to your health care provider who will determine if treatment is needed.  

What happens if DXA detects weak bones?

Depending on the severity of bone loss, your health care provider may recommend watchful waiting or treatment.

The most widely prescribed treatments are a class of drugs known as bisphosphonates, which can be taken in pill form and slow bone loss. Another option—denosumab—requires an injection every six months. Some other injectable medications, such as teriparatide and others, stimulate bone formation. For younger people experiencing symptoms of menopause, hormone replacement therapy can slow the progression of bone loss.

“All drugs approved by the Food and Drug Administration for the treatment of osteoporosis reduce the risk of fracture. They are safe and most tolerate them without difficulty,” Walker says.

“Exercise and a healthy diet can help slow age-related bone loss, but their direct effect on bone density is small.”