Understanding Your DEXA Scan Results

What is a DEXA scan?

A DEXA scan (dual-energy X-ray absorptiometry) is a quick, painless imaging test that measures your bone mineral density — essentially, how strong and dense your bones are. It uses a very low dose of radiation — far less than a standard chest X-ray — and takes about 10–15 minutes.

The scan focuses on two areas: your lumbar spine (lower back) and your hip (specifically the femoral neck and total hip). These are the sites most vulnerable to fractures from osteoporosis and the most reliable for tracking changes over time.

Understanding your T-score

The main number on your DEXA report is your T-score. This compares your bone density to that of a healthy 30-year-old adult at peak bone mass. The result is expressed as a number above or below zero:

• T-score of -1.0 or higher: Normal bone density. Your bones are within the expected range.
• T-score between -1.0 and -2.5: Osteopenia — bone density is lower than normal but not yet in the osteoporosis range. Think of this as a yellow light, not a red one. Many people with osteopenia never develop osteoporosis, especially with appropriate prevention.
• T-score of -2.5 or lower: Osteoporosis — bone density is significantly reduced, and fracture risk is elevated. This is a clinical diagnosis, but it’s an important one to know about: osteoporosis is highly treatable.

Your T-score tells us about bone density, but it’s only one piece of the fracture risk puzzle. Other factors — your age, fracture history, medications, and fall risk — matter just as much.

Each full point of T-score roughly corresponds to a doubling of fracture risk. So a T-score of -3.0 carries meaningfully higher risk than -2.0 — but that risk is modifiable with treatment.

What about Z-scores?

Your report may also include a Z-score, which compares your bone density to people your own age and sex rather than to a 30-year-old.

• For postmenopausal women and men over 50, the T-score is what we use for diagnosis.
• For premenopausal women, men under 50, and children, the Z-score is more appropriate. In these groups, we don’t use the terms “osteopenia” or “osteoporosis” based on T-scores — instead, a Z-score of -2.0 or lower is described as “below the expected range for age.”
• A very low Z-score in a younger person raises the question of secondary causes — something specific that’s driving bone loss, such as a medication, a hormonal issue, or a nutritional deficiency.

FRAX: your 10-year fracture risk

FRAX is a calculator developed by the World Health Organization that estimates your 10-year probability of having a major osteoporotic fracture (hip, spine, forearm, or shoulder) and your 10-year probability of having a hip fracture specifically.

It takes into account several factors beyond your T-score:

• Your age, sex, and BMI
• Whether you’ve had a prior fracture
• Whether a parent fractured a hip
• Current smoking and alcohol use
• Whether you’re on glucocorticoids (like prednisone)
• Whether you have rheumatoid arthritis or other secondary causes

We use FRAX to help decide whether to start medication — particularly for patients with osteopenia, where the T-score alone doesn’t give us the full picture. Current guidelines generally recommend treatment when the 10-year risk of a major fracture is 20% or higher, or the 10-year hip fracture risk is 3% or higher.

How often should you get a DEXA?

• Every 2 years is the standard interval for most patients being monitored or treated for osteoporosis.
• Sooner — sometimes at 1 year — if you’ve started a new osteoporosis medication and we want to confirm it’s working, or if you’ve had a significant change in clinical status (such as starting long-term prednisone).
• Less frequently if your initial scan was normal and you have no major risk factors — your doctor may recommend repeating it in 3–5 years or longer.

Medicare covers a DEXA scan every 2 years for qualifying patients. If your insurance requires a longer interval, we can discuss options.

What can affect your results?

DEXA results are generally reliable, but a few things can influence the numbers:

• Different machines: If you get your DEXA at a different facility than last time, the results may not be directly comparable. Whenever possible, try to use the same machine and same location for follow-up scans.
• Vertebral artifacts: Arthritis, compression fractures, aortic calcifications, and even prior spinal surgery can falsely elevate the spine T-score — making your bones look denser than they actually are. When we see a spine T-score that looks suspiciously good, we pay closer attention to the hip.
• Significant weight changes: Gaining or losing a substantial amount of weight between scans can affect the measurement, since body composition influences X-ray absorption.
• Positioning: Consistent positioning on the scan table matters. Well-trained technologists follow standardized protocols to minimize this variable.

What does a diagnosis of osteoporosis mean?

If your DEXA shows osteoporosis, it’s natural to feel concerned — but this is a treatable condition, not an irreversible sentence. Effective medications can reduce fracture risk significantly, and lifestyle strategies like weight-bearing exercise, adequate calcium and vitamin D, and fall prevention all support bone health alongside treatment.

The purpose of identifying osteoporosis is to prevent fractures before they happen — particularly hip and spine fractures that can have a major impact on independence and quality of life. We monitor progress with follow-up DEXA scans and sometimes blood work.

A diagnosis of osteoporosis means we found something important early enough to do something about it. Your doctor will discuss specific treatment options with you based on your fracture risk, medical history, and preferences.

Why rheumatology cares about your bones

Many rheumatic conditions — and the medications we use to treat them — affect bone health directly. Rheumatoid arthritis itself is a risk factor for osteoporosis. Glucocorticoids (prednisone, methylprednisolone) are one of the most common causes of secondary osteoporosis. Chronic inflammation, reduced mobility, and hormonal changes all contribute.

This is why we screen for bone loss proactively and don’t wait for a fracture to tell us there’s a problem. If you’re due for a DEXA scan or have questions about your bone health, bring it up at your next visit.

This handout is provided for educational purposes and does not replace individualized medical advice. Always follow the specific instructions given by your rheumatologist.