Bone Health Screening: Understanding DEXA Scan Results and Fracture Risk

When you hear the word DEXA scan, it might sound technical, even intimidating. But here’s the truth: it’s one of the simplest, safest, and most important tests you can get for your bones-especially as you get older. Unlike a regular X-ray that just shows broken bones, a DEXA scan tells you if your bones are getting weak before they break. And that’s the whole point. Osteoporosis doesn’t come with pain or warning signs. It’s silent. By the time you fracture a hip or spine, it’s often too late to undo the damage. A DEXA scan catches it early. But knowing what the numbers mean? That’s where most people get lost.

What Exactly Is a DEXA Scan?

A DEXA scan-short for dual-energy X-ray absorptiometry-is a quick, painless test that measures how dense your bones are. It uses two very low-dose X-ray beams, one high-energy and one low-energy, to tell the difference between bone and soft tissue. The machine passes over your lower spine and hip, sometimes your forearm, and calculates how much mineral (mostly calcium) is packed into each square centimeter of bone. The result? A number in grams per square centimeter. But that number alone doesn’t tell you much. What matters is how it compares to two reference groups: healthy young adults and people your own age.

The radiation you get from a DEXA scan is tiny. Less than what you’d absorb from a day’s worth of natural sunlight. You’re exposed to more radiation on a short flight. The whole test takes about 10 minutes. You lie still on a table while the scanner moves above you. No needles. No fasting. No special prep. You just wear clothes without metal zippers or buttons. That’s it.

What Do the Numbers Mean? T-Score vs. Z-Score

After your scan, you’ll get two numbers: a T-score and a Z-score. Most people only hear about the T-score, but both matter.

The T-score compares your bone density to that of a healthy 30-year-old adult of the same sex and race. This is the number doctors use to diagnose osteoporosis. Here’s what it means:

• T-score of -1.0 or higher: Normal bone density
• T-score between -1.0 and -2.5: Osteopenia (low bone mass-your bones are weaker than normal, but not yet osteoporosis)
• T-score of -2.5 or lower: Osteoporosis

So if your T-score is -2.7, you have osteoporosis. Not borderline. Not maybe. That’s the diagnosis. And it’s not rare. About half of all women over 50 will have a T-score in the osteoporosis range at some point.

The Z-score compares your bone density to people your own age, sex, and ethnicity. This is useful if you’re under 50, pregnant, or have a medical condition that affects bone health. A Z-score below -2.0 means your bones are thinner than most people your age-and that’s something to dig into. It could point to an underlying issue like low vitamin D, thyroid problems, or even celiac disease.

Don’t confuse the two. A T-score of -1.8 might sound scary, but if you’re 45, your Z-score might be -0.5-which means your bones are actually fine for your age. That’s why both numbers matter.

Why a DEXA Scan Alone Isn’t Enough

Here’s the big mistake most people make: they think a low T-score = automatic fracture risk. Not true.

Some people with osteoporosis (T-score below -2.5) never break a bone. Others with osteopenia (T-score between -1 and -2.5) fracture easily. Why? Because bone density isn’t the whole story. Bone quality matters too. Are your bones brittle? Do they have micro-cracks? Are they losing their internal structure? DEXA can’t see that.

That’s where the FRAX tool comes in. Developed by the World Health Organization, FRAX takes your T-score and adds in other risk factors: age, weight, smoking, alcohol use, family history of hip fracture, steroid use, rheumatoid arthritis, and more. It doesn’t guess. It calculates your 10-year chance of breaking a hip or major bone. If your risk is over 20% for a major fracture or over 3% for a hip fracture, treatment is usually recommended-even if your T-score is only in the osteopenia range.

One real case: a 68-year-old woman had a T-score of -2.7. She was thin, smoked half a pack a day, and her mom broke her hip at 72. Her FRAX score showed a 24% chance of a major fracture in 10 years. She started a bone-building medication. Two years later, she’s still active. No fractures. That’s the power of combining data.

Who Should Get a DEXA Scan?

You don’t need one just because you’re over 50. But if you fit any of these, you should talk to your doctor about scheduling one:

• Women 65 and older
• Men 70 and older
• Postmenopausal women under 65 with risk factors (low body weight, smoking, family history)
• Adults who’ve had a fracture after age 50
• People taking long-term steroid pills (like prednisone)
• Those with conditions linked to bone loss: rheumatoid arthritis, type 1 diabetes, celiac disease, or hyperthyroidism
• People who’ve lost more than 1.5 inches in height

Medicare covers a DEXA scan every two years for people who meet these criteria. Most private insurers do too. But here’s the catch: many doctors don’t offer it unless you ask. If you’re at risk, don’t wait for them to bring it up.

What About Other Tests? Are They Better?

You might hear about QCT (quantitative CT), ultrasound, or even regular X-rays as alternatives. Here’s the reality:

• QCT gives a 3D view of bone and measures volume, not just density. But it uses 100 times more radiation than DEXA and costs twice as much. It’s not used for routine screening.
• Ultrasound (on the heel) is cheap and radiation-free. But it’s not accurate enough for diagnosis. It’s only good for initial risk screening.
• Regular X-rays only show fractures or severe bone loss. By the time you see it on an X-ray, you’ve already lost 30% of your bone mass.

DEXA is still the gold standard. It’s the only test the U.S. Preventive Services Task Force recommends for routine screening. And it’s the only one validated against actual fracture outcomes in large studies across decades.

Limitations and Pitfalls

No test is perfect. DEXA has blind spots:

• It can’t tell the difference between cortical (outer) and trabecular (inner) bone. That matters because osteoporosis often starts inside.
• Arthritis, spinal fusion, or metal implants can throw off the numbers. Your technician needs to know your history.
• It doesn’t show if you’ve already had silent spinal fractures. That’s why some scans include a VFA-vertebral fracture assessment-which looks for hidden breaks in your spine.
• For people with very high body weight, the machine may not be accurate. Some newer models handle this better.

Also, if you’ve had a scan before, make sure you go to the same facility. Different machines can give slightly different results. Comparing scans across different brands or settings can mislead your doctor.

What Happens After the Scan?

If your T-score is normal? Great. Keep doing what you’re doing: get enough calcium and vitamin D, stay active, avoid smoking, and limit alcohol.

If you have osteopenia? That’s your wake-up call. Lifestyle changes can stop or even reverse bone loss. Weight-bearing exercise (walking, lifting weights, dancing) is the most powerful tool. Studies show it can improve bone density by 1-3% per year. That’s more than most medications.

If you have osteoporosis? You’ll likely need medication. Options include bisphosphonates (like alendronate), denosumab, or newer drugs like romosozumab. They don’t fix bones overnight. But they reduce fracture risk by 30-70% over three years. And they work best when paired with lifestyle changes.

And if you’ve had a fracture? Even if your T-score is only borderline, you’re at high risk for another. Treatment is almost always recommended.

Why So Many People Are Still Being Missed

Here’s the uncomfortable truth: millions of people with osteoporosis never get screened. Especially women of color. In 2022, only 22% of Black women and 18% of Hispanic women over 65 had a DEXA scan-compared to 41% of white women. That’s not a gap in knowledge. It’s a gap in access, in doctor referrals, in awareness.

And younger people? Many think osteoporosis is an “old lady disease.” It’s not. Menopause, eating disorders, intense athletic training, and certain medications can cause bone loss in your 30s and 40s. If you’ve had a stress fracture, irregular periods, or a history of anorexia, get tested-even if you’re under 50.

What’s Next for Bone Health?

Science is moving fast. New tools are being added to DEXA scans. One is the Trabecular Bone Score (TBS), which analyzes the texture of your spine on the scan to estimate bone structure quality. It doesn’t need extra radiation. Just a software upgrade. Studies show TBS improves fracture prediction by up to 18% on its own.

Artificial intelligence is now being trained to spot tiny spinal fractures in DEXA images-something even experienced radiologists sometimes miss. One 2023 study showed AI detected 95% of hidden fractures, compared to 78% by humans.

But none of this replaces the need for early screening. The best future for your bones isn’t in fancy tech. It’s in getting tested now.