What is a DEXA Scan?
A DEXA scan, or Dual-Energy X-ray Absorptiometry, is a safe, painless, and non-invasive procedure that measures bone mineral density (BMD). This quick test uses low-dose X-rays to assess the strength of your bones, typically focusing on the hips and spine, which are common sites for fractures. The test helps healthcare providers diagnose osteoporosis, a condition that causes bones to become weak and brittle, and osteopenia, which is a precursor stage of bone loss. Early detection through a DEXA scan is key for monitoring bone health over time and implementing strategies to prevent fractures.
Standard Screening Guidelines by Age
For women without significant risk factors, the standard recommendation for a baseline DEXA scan is at age 65. This guideline is supported by multiple health organizations, including the U.S. Preventive Services Task Force (USPSTF). The reason for this age recommendation is that bone mass loss accelerates significantly after menopause, and the risk of osteoporotic fractures increases with age. Establishing a baseline scan at 65 provides a snapshot of bone health to guide future decisions and treatment plans.
Screening Earlier: Recognizing Risk Factors
Many women need to start screening earlier than age 65 due to personal and lifestyle risk factors. For postmenopausal women under 65, a DEXA scan may be necessary if one or more of the following apply:
- Parental History of Hip Fracture: Having a mother or father who broke a hip significantly increases your own risk.
- Low Body Weight: Weighing less than 127 pounds or having a body mass index (BMI) under 20 kg/m² is a major risk factor.
- History of a Fragility Fracture: If you have experienced a fracture from a fall from a standing height or less, it's a strong indicator for a scan.
- Early Menopause: Natural or surgical menopause before age 45 is a risk factor, as it leads to an earlier decline in protective estrogen levels.
- Smoking: Current tobacco use is strongly associated with decreased bone density.
- Excessive Alcohol Consumption: Consuming more than two drinks per day on most days can increase risk.
- Certain Medications: Long-term use (3+ months) of certain drugs, such as corticosteroids (e.g., prednisone), some anti-seizure medications, or high-dose thyroid hormone replacement, can impact bone health.
- Medical Conditions: Some diseases, including rheumatoid arthritis, chronic kidney or liver disease, and type 1 diabetes, are linked to higher osteoporosis risk.
Interpreting Your Results: T-Scores and Z-Scores
Your DEXA scan results will include two key scores:
- T-score: This number compares your bone density to that of a healthy young adult at peak bone mass.
- Normal: T-score is -1.0 or higher.
- Osteopenia (Low Bone Mass): T-score is between -1.0 and -2.5.
- Osteoporosis: T-score is -2.5 or lower.
- Z-score: This compares your bone density to that of other people in your same age, sex, and ethnic group. An unusually high or low Z-score may suggest an underlying medical condition is affecting your bone density.
Comparison of Screening Guidelines
Several health organizations provide guidance on DEXA screening. While they all agree on the importance of screening, particularly for older women, there can be slight variations in specific age and risk factor thresholds.
| Organization | General Women 65+ Recommendation | Screening for Younger Postmenopausal Women (under 65) |
|---|---|---|
| U.S. Preventive Services Task Force (USPSTF) | Recommends screening for osteoporosis to prevent fractures. | Recommends screening for those with increased risk based on clinical risk assessment. |
| Bone Health and Osteoporosis Foundation (BHOF) | Recommends BMD testing for all women 65 and older. | Recommends testing for postmenopausal women 50-69 based on risk factor profile. |
| American College of Obstetricians and Gynecologists (ACOG) | Recommends bone density screening starting at 65. | Suggests selective screening for postmenopausal women with risk factors or fracture history. |
Regardless of the specific guidelines, the emphasis is on a personalized assessment, taking into account all your individual risk factors. The gold standard for any woman uncertain of her screening needs is to consult with her primary care physician. For up-to-date recommendations on screening and treatment, you can also review the U.S. Preventive Services Task Force Recommendations.
Next Steps After a DEXA Scan
If your DEXA scan reveals low bone mass or osteoporosis, your doctor may recommend a range of interventions. These can include:
- Lifestyle Modifications: Adjustments to your diet to increase calcium and vitamin D intake are often the first step. Weight-bearing exercises like walking, jogging, or using resistance weights can also help strengthen bones.
- Supplements: If dietary intake isn't sufficient, your provider may recommend calcium and vitamin D supplements.
- Medications: For more advanced cases of osteoporosis, prescription medications such as bisphosphonates or other injectables can help slow bone loss and rebuild bone density.
- Follow-Up Scans: The frequency of repeat scans depends on your initial results and risk profile. Higher-risk individuals may need a scan every two years, while those with minimal bone loss may have a longer interval.
Conclusion: Taking Control of Your Bone Health
Osteoporosis is a preventable and treatable condition, but early detection is critical. While age 65 is the standard guideline, a woman should start getting DEXA scans earlier if she has specific risk factors. By understanding your individual risk profile and consulting with your healthcare provider, you can create a proactive plan to protect your bones and ensure healthy aging for years to come. Don't wait until a fracture occurs; take charge of your bone health today.
