Understanding the purpose of a DEXA scan
A Dual-Energy X-ray Absorptiometry (DEXA) scan is a quick, non-invasive imaging test that measures bone mineral density (BMD). This measurement is a key indicator for diagnosing osteoporosis and predicting future fracture risk. The scan uses low-dose X-rays to assess bone strength, typically focusing on the most susceptible areas like the hip, spine, and forearm.
Bone density naturally peaks around age 30, after which it gradually declines. For women, this loss accelerates significantly after menopause due to declining estrogen levels. Because osteoporosis often develops without noticeable symptoms, a fragility fracture is sometimes the first sign of the disease. Regular screening is critical for early detection, allowing for lifestyle changes or medication to mitigate further bone loss and reduce fracture risk.
National screening guidelines by age and gender
Medical organizations, including the United States Preventive Services Task Force (USPSTF), provide clear guidelines on when individuals should consider bone density screening based on age and gender. While these are broad recommendations, they form the foundation for a doctor's decision.
For Women
- Age 65 or older: The USPSTF and other major health organizations recommend routine DEXA screening for all women aged 65 and over. This is considered the standard age for initial screening in women without specific risk factors.
- Postmenopausal and under 65: Earlier screening is recommended for postmenopausal women under 65 who have increased risk factors for osteoporosis. For example, a 50-year-old postmenopausal woman with a parental history of hip fracture may need a scan much sooner.
For Men
- Age 70 or older: The standard recommendation for men is to begin routine screening at age 70. Similar to women, this is the benchmark for men without significant risk factors for bone loss.
- Under 70 with risk factors: For men with specific risk factors, including certain medical conditions or lifestyle habits, screening may be advised earlier. The decision should be made in consultation with a healthcare provider.
Key risk factors that influence screening timing
Age is a major factor, but it is not the only one. A variety of lifestyle, medical, and genetic factors can accelerate bone loss and necessitate an earlier DEXA scan. Your doctor will assess your individual risk profile to determine the best timing for you.
- Lifestyle factors: Smoking and excessive alcohol consumption are known to contribute to bone loss. A sedentary lifestyle also increases risk, as weight-bearing exercise is vital for maintaining bone density. A person with these habits may need earlier screening.
- Family and personal history: A family history of osteoporosis, especially a parent with a hip fracture, is a significant risk factor. A personal history of a fragility fracture—a break resulting from a minor fall—is a direct indicator of compromised bone health and warrants a scan regardless of age.
- Low body weight: Thin and small-framed individuals tend to have less bone mass to begin with, putting them at a higher risk for osteoporosis as they age.
- Certain medical conditions: Several health issues are linked to increased bone loss, including rheumatoid arthritis, chronic kidney or liver disease, and type 1 diabetes. These conditions should prompt a discussion about early screening.
- Medications: Long-term use of certain medications, such as corticosteroids, some anti-seizure drugs, and proton pump inhibitors, can interfere with bone metabolism and lead to lower bone density.
The DEXA scan procedure: what to expect
The DEXA scan is a simple and quick outpatient procedure. You will lie on a padded table while a mechanical arm passes over your body, scanning your hip and spine. The entire process is painless and takes approximately 10 to 20 minutes. It is important to wear loose, comfortable clothing without any metal fasteners like zippers, buttons, or buckles, as these can interfere with the image quality. The amount of radiation is minimal, far less than a standard chest X-ray.
Interpreting your DEXA scan results
Your DEXA scan results are reported as T-scores and Z-scores. Understanding these scores is key to interpreting your bone health status.
- T-Score: This score compares your bone density to that of a healthy young adult at peak bone mass. It is the primary score used to diagnose osteoporosis in postmenopausal women and men aged 50 and older.
- A T-score of -1.0 or higher is considered normal bone density.
- A T-score between -1.0 and -2.5 indicates low bone mass, or osteopenia.
- A T-score of -2.5 or lower indicates osteoporosis.
- Z-Score: This score compares your bone density to that of other people in your same age, sex, and ethnic group. A low Z-score can signal that a medical condition other than normal aging may be causing bone loss.
When to get a bone density test: a comparison
This table illustrates various scenarios and the likely recommendation for when to get a DEXA scan, highlighting how risk factors can alter the standard age guidelines.
| Patient Profile | Standard Recommendation | Recommendation with Risk Factors |
|---|---|---|
| 65-year-old woman with no risk factors | Screen at age 65 | N/A |
| 55-year-old woman with a parent who had a hip fracture | Wait until age 65 | Screen sooner due to parental history |
| 70-year-old man with no risk factors | Screen at age 70 | N/A |
| 62-year-old man who is a current smoker | Wait until age 70 | Screen sooner due to lifestyle risk factors |
| 58-year-old postmenopausal woman with a history of long-term corticosteroid use | Wait until age 65 | Screen sooner due to medication-related bone loss |
The ultimate decision: consulting your doctor
While guidelines provide a roadmap, the decision on when to get a DEXA scan should always be a conversation with your healthcare provider. Your doctor can accurately assess your full health history, family background, and lifestyle to determine the most appropriate time for you to be screened. Based on your initial results, they will also advise on the frequency of future scans and any preventative or treatment measures needed.
By taking a proactive approach to bone health, individuals can significantly reduce their risk of fractures and maintain their mobility and quality of life as they age. For more comprehensive information on osteoporosis and bone health, visit the Bone Health and Osteoporosis Foundation website.
