A foundation for strong bones

How DEXA scans support bone health

Mature couple walking through the countryside.

Hinde Butts has had osteoporosis for what seems like forever. At a lively 80 years old, she can hardly remember when her bone health hasn’t been one of her priorities.

“I was first diagnosed at least 20 years ago,” she said. “But thanks to all the different medicines that hold it at bay, I’m still able to walk, talk and complain — everything that women are supposed to do.”

Osteoporosis is a disease that causes bones to become weak as they lose density, leading to an increased risk for fracture. In the past, Butts’s osteoporosis has significantly deteriorated her jaw bone, but it most commonly targets the spine, hips and wrists.

Because she has been fortunate enough to never experience pain from her osteoporosis, Butts believes the condition can sneak up on people.

“You never see it in yourself, so you wouldn’t know about it until you have a bone scan,” she said. “When you go to the doctor and you’re already not as tall as you are on your driver’s license — that’s your first hint.”

Understanding a bone scan

Butts first found out about her weakening bones from a dual energy X-ray absorptiometry — or DEXA — bone scan. Testing bone density, or how strong bones are, is the only way to diagnose osteoporosis.

The best type of bone mineral density test is a DEXA scan. DEXA is a non-invasive radiologic test that measures bone density. Two X-ray beams, one high energy and one low energy, are aimed at a patient’s bones while a machine measures the amount of energy that passes through each of them. This measurement reveals how much calcium is in the bones.

Brandon Allard, M.D., practices internal medicine at Sanford Health and is one of the physicians who reads DEXA scans to determine risk levels for fracture and osteoporosis.

“In particular, we look at the vertebral bones of the lower back and the hips, which are important sites for bone density assessment,” Dr. Allard said. “And if needed we add the wrist, which is a third site that’s considered useful for diagnosis.”

As Dr. Allard further explained it, interpreting a DEXA scan is more about assessing a mathematically calculated number — reported as the T-score — than it is about visually examining images.

“Visually the images of high and low density bones actually don’t look that different,” he said. “It’s dependent on the software and the computers that run the DEXA machine to mathematically assess the bone density.”

A T-score shows how much higher or lower a patient’s bone density is to that of a healthy 30-year-old, the age when bones are at their strongest. The lower the score, the weaker the bones.

A DEXA scan can pair with a FRAX score to provide the full picture of a patient’s fracture risk. A FRAX score is a risk calculator based on a questionnaire that’s completed before a patient gets their DEXA scan. The questionnaire asks about factors such as family history and steroid usage.

“What a bone looks like tells you something about its strength, but the person’s characteristics give you additional information,” said Dr. Allard.

Safeguarding bone health

According to the National Osteoporosis Foundation, of the estimated 10 million Americans with osteoporosis, about 80 percent are women.

“Estrogen protects women from the rapid thinning of bones until menopause and then when their estrogen levels drop there’s a pretty predictable and abrupt drop in bone density,” said Dr. Allard.

Because of this, the U.S. Preventive Services Task Force recommends screening for osteoporosis in all women 65 years or older.

For men, getting a screening is based more on individual risk or history of fractures. Men’s bones are generally more protected by testosterone, as they don’t experience a menopause equivalent.

Proactive steps to help preserve bone density include staying physically active with weight-bearing activities and maintaining a well-balanced diet rich in calcium and vitamin D. Butts said she hopes younger people start thinking about their bone health.

“All of a sudden 10 years go by and you’re not standing up as straight,” she said.

One step ahead of fractures

Having a DEXA scan helps teams like Dr. Allard’s intervene early and prevent fractures, which often lead to a host of other problems.

“A fragility fracture — a fracture with no trauma — is a very ominous event that has the same risk to it as an acute cardiac event,” Dr. Allard said. “It’s serious business. Patients have a lot of disability and shortened life expectancy after.”

Many never get back to their level of activity before the break.

“It’s a common path to have patients who are limited functionally afterward, especially when they’re older. It takes them out of their productive, gainful life,” he said.

Dr. Allard often sees a certain acceptance when it comes to aging, where people expect to break bones as a natural part of getting older.

“But it’s not necessarily a normal part of aging,” Dr. Allard said. “No one should break bones just going through their life. There’s an underlying problem there that needs to be addressed, but we don’t have to accept people breaking bones over and over again.”

Getting a bone scan

A DEXA scan generally takes about 10 minutes to complete. It’s painless and involves a low amount of radiation. Patients don’t even have to change into a gown.

“The DEXA scan itself is nothing to get worried about. You lay on a table and there’s a machine that goes back and forth over you. Piece of cake,” Butts said.

Since her first DEXA bone scan, Butts has had at least four more. Getting multiple scans over time allows the physician reading them to make a comparison to previous studies and examine the trajectory of the bone density — whether it’s going up or down.

Fortunately for Butts, her bone density is now holding steady. But checking bone density can be a neglected part of routine care, so she encourages others to ask their doctor about getting a scan.

“It’s so worth it. It’s a half hour of your time,” she said. “In fact, it’s kind of relaxing. If you’re in a tired mood, you could fall asleep.”

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Posted In Imaging, Orthopedics, Women's

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