Learn What Your DEXA Scan T-Score Means for Bone Strength

What Do Your DEXA Scan T-Score Numbers Mean?

A dual-energy X-ray absorptiometry scan, or DXA/DEXA, measures bone mineral density, usually at the hip and spine. Your T-score compares your bone density with that of a healthy young adult. A lower score means lower bone density and higher fracture risk. For the basics, see T-score meaning explained simply.

A central DEXA scan is the standard test for evaluating bone health. The machine passes two low-dose X-ray beams through your body, typically focusing on the hip and lower spine. Dense bone blocks more of the beam, while thinner bone lets more pass through.

A computer then calculates your bone mineral density, or BMD, which is the amount of mineral mass in a square centimeter of bone tissue. Because raw mineral numbers are hard to interpret on their own, your results are reported as T-score. This T-score uses a standard deviation scale to compare your BMD to the average bone mass of a healthy young adult around age 30, when skeleton density is at its highest. Each point below zero represents one standard deviation below that peak. For a deeper look at the raw numbers, read our guide on how to interpret bone density. You can also review the bone mineral density testing guide from the National Library of Medicine for more testing details.

Normal vs. Low Bone Density: The WHO Categories

The World Health Organization established standard categories so clinicians and adults 65 and older can easily understand bone density levels:

• Normal Bone Density (T-score of -1.0 or higher): Your bone mineral density is close to or above the young adult average. Your bones have good mineral content, though fracture risk still depends on age, fall risk, medications, and other factors.
• Low Bone Density or Osteopenia (T-score below -1.0 and above -2.5): Your bone density is lower than the young adult reference range, but it has not reached the threshold for osteoporosis. You can explore our osteopenia range chart to see where specific numbers fall within this range.
• Osteoporosis (T-score of -2.5 or below): Bones have become significantly thinner and more fragile. Learn what a T-score below -2.5 represents for long-term bone care.
• Severe or Established Osteoporosis: This usually means a T-score of -2.5 or lower plus one or more past fragility fractures, such as a break from a minor fall or normal daily activity.

Medical organizations use these defined thresholds as osteoporosis diagnostic criteria to help select appropriate treatments.

T-Score vs. Z-Score: Why Both Numbers Matter

A T-score compares your bone density to a healthy young adult around age 30, when human skeleton mass peaks. A Z-score, however, compares your bone density to an average person of your exact same age, sex, and ethnic background.

Understanding what T-scores and Z-scores mean helps doctors tell the difference between normal age-related bone changes and secondary causes of bone loss. If an older adult has an unusually low Z-score (typically -2.0 or lower), their bone density is significantly lower than their age peers. This prompts clinicians to check for underlying medical issues, such as thyroid problems, vitamin deficiencies, or medication side effects.

How Does Your T-Score Relate to Bone Fracture Risk?

Lower bone density is linked to higher fracture risk. On average, each one-point drop in your T-score is associated with about 1.5 times the risk of a fracture, and more than twice the risk of a hip fracture when density is measured at the hip. These are relative increases, not your actual odds of breaking a bone. Your real risk also depends on your age, past fractures, fall history, and other factors, which is why clinicians often use a tool called FRAX to estimate it.

It also helps to separate relative risk from absolute risk. Relative risk compares you with another person or group. Absolute risk estimates how likely you are to have a fracture over a set period of time. Two people can have the same T-score but different absolute risks if one is older, has fallen before, smokes, or has a parent who had a hip fracture.

However, a T-score is only one part of the equation. Clinicians also use calculation tools like the Fracture Risk Assessment Tool, or FRAX. The FRAX tool evaluates your bone density along with personal clinical factors, including your age, body weight, smoking history, alcohol use, parental history of hip fracture, and long-term medication use. It calculates your 10-year probability of experiencing a major osteoporotic fracture or a hip fracture. For insights on how clinicians evaluate these combined factors, see a physician review of bone density metrics.

This is why your doctor may not treat every T-score the same way. A T-score in the osteopenia range may still deserve close attention if your FRAX score is high or if you have already had a low-trauma fracture. On the other hand, a mildly low T-score with few other risk factors may lead to nutrition changes, fall prevention, and scheduled monitoring before medication is considered.

What Factors Change Your Bone Density and T-Score?

Bone density changes continuously throughout life due to bone remodeling, a natural cycle where specialized cells break down old bone and replace it with new bone.

As people age, bone breakdown slowly outpaces bone building. Several key factors influence how quickly bone density declines:

• Hormonal Changes: Estrogen helps protect bone by limiting the activity of cells that break bone down. When estrogen drops around menopause, bone loss speeds up, especially in the first few years. In men, sex hormones also help maintain bone, and their gradual decline with age contributes to slower bone loss.
• Medical Conditions: Conditions that cause chronic inflammation or interfere with nutrient absorption, such as celiac disease or rheumatoid arthritis, can reduce bone strength. Read our guide on understanding osteoporosis for an overview of these risks.
• Medications: Some prescription drugs can weaken bone, especially glucocorticoids like prednisone taken for three months or more, which slow new bone formation and speed up bone loss.
• Nutrition and Lifestyle: Inadequate calcium, insufficient vitamin D, low physical activity, tobacco use, and excessive alcohol intake all impair bone remodeling.

Clinicians rely on established dual-energy X-ray absorptiometry standards to monitor these physiological shifts over time.

How Often Should You Monitor Your Bone Density?

Most older adults should have a follow-up DEXA scan every 2 to 5 years, though high-risk individuals or those on osteoporosis medications may need testing every 2 years.

The U.S. Preventive Services Task Force recommends routine bone mineral density screening for all women aged 65 and older, as well as for younger postmenopausal women with elevated clinical risk. Guidelines from medical organizations suggest repeat intervals based on your initial score and overall risk level:

• Normal or Slightly Low Bone Density (T-score -1.49 or higher): In one large study of women 67 and older, an estimated 1 in 10 developed osteoporosis after about 17 years.
• Moderately Low Bone Density (T-score -1.50 to -1.99): The same study estimated a window of about 5 years (4.7) before 1 in 10 reached osteoporosis.
• Close to the Osteoporosis Range (T-score -2.00 to -2.49): The same study estimated about 1 year (1.1) before 1 in 10 reached osteoporosis, so follow-up may be needed that soon.
• Higher Risk or Changing Treatment: These are estimates, not fixed rules. Your clinician may scan sooner if you develop new risks, start steroids like prednisone, or begin or change osteoporosis medication.

For more details on screening schedules, see our overview of DEXA scan frequency guidelines. According to Medicare.gov, Medicare Part B covers a routine bone mass measurement once every 24 months for eligible individuals at risk for bone loss, with more frequent scans permitted when medically necessary. Exact coverage terms may vary by plan type.

Proactive Steps to Support Bone Health and Prevent Loss

Protecting bone strength requires a combination of clinical monitoring, targeted exercise, and proper nutrition. Older adults with osteoporosis, osteopenia, or a past fracture can benefit from working with a qualified professional to build a personalized exercise plan that progressively loads the hip and spine.

Groove Health is a Medicare covered bone health program for adults 65 and older that pairs each member with a physician and a physical therapist who designs a personalized exercise plan.

Nutrition for Bone Maintenance

Your body needs steady raw materials to maintain bone structure and support mineral density:

• Calcium: NIH ODS recommends 1,200 mg daily for women over 50, 1,000 mg for men 51 to 70, and 1,200 mg for men 71+. Food sources are best: dairy, fortified foods, canned fish with bones, kale, collards, and bok choy. Adults over 50 should not exceed 2,000 mg daily from food and supplements combined.
• Vitamin D: NIH ODS recommends 600 IU daily for adults 51 to 70 and 800 IU for adults 71+. Vitamin D helps your body absorb calcium. Sources include fortified milk, fatty fish, supplements, and sunlight, though vitamin D production from skin declines with age and is limited in northern winters.
• Protein: The baseline adult recommendation is 0.8 grams per kilogram of body weight daily, though some expert groups suggest 1.0 to 1.2 g/kg for older adults to help preserve muscle. Adequate protein also supports bone health. If you have kidney disease, ask your clinician before increasing protein.

Key Takeaways: Reading Your T-Score

A DEXA scan provides essential insight into your bone health by comparing your bone mineral density against a healthy young adult reference standard. Understanding whether your T-score reflects normal bone density, osteopenia, or osteoporosis allows you and your doctor to evaluate your overall fracture risk and establish an appropriate screening schedule.

Tracking your bone mineral density over time helps ensure that changes in bone strength are caught early. Pairing your scan results with proactive steps—such as targeted, progressive exercise designed to build bone strength and reduce fracture risk—empowers you to protect your skeleton and maintain long-term independence.

Works Cited

1. Curry SJ, Krist AH, Owens DK, et al. “Screening for Osteoporosis to Prevent Fractures: US Preventive Services Task Force Recommendation Statement.” JAMA, 2018.
2. Gourlay ML, Fine JP, Preisser JS, et al. “Bone-Density Testing Interval and Transition to Osteoporosis in Older Women.” New England Journal of Medicine, 2012.
3. Marshall D, Johnell O, Wedel H. “Meta-analysis of How Well Measures of Bone Mineral Density Predict Occurrence of Osteoporotic Fractures.” BMJ, 1996.
4. Medicare.gov. “Bone Mass Measurements.” Centers for Medicare & Medicaid Services, 2026.
5. NIH Office of Dietary Supplements. “Calcium: Health Professional Fact Sheet.” National Institutes of Health, 2026.
6. NIH Office of Dietary Supplements. “Vitamin D: Health Professional Fact Sheet.” National Institutes of Health, 2026.
7. World Health Organization Study Group. “Assessment of Fracture Risk and Its Application to Screening for Postmenopausal Osteoporosis.” WHO Technical Report Series 843, 1994.

This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional for diagnosis and treatment. If you are on Medicare and interested in a personalized bone health program, you can check your eligibility at groovehealth.com.