Understanding Your Bone Density (DEXA) Scan Results

Bone density testing is one of the most important preventive health scans for women over 50 and men over 65 — yet the results report is often handed to patients with little explanation. In Singapore, bone density testing is available at major restructured hospitals and private imaging centres. In Australia, a Medicare rebate (MBS item 12306) applies for eligible patients including post-menopausal women and those on long-term corticosteroids. In North America, the United States Preventive Services Task Force (USPSTF) recommends routine DEXA screening for all women from age 65. Understanding your T-score and Z-score — and knowing the right questions to ask your doctor — allows you to take concrete steps to protect your bone health before a fracture occurs.

1. What Is a DEXA Scan and Why Is It Ordered?

A DEXA (Dual-Energy X-ray Absorptiometry) scan is a low-radiation imaging test that measures bone mineral density (BMD) in grams per square centimetre (g/cm²). It is most commonly performed at the lumbar spine (lower back, L1–L4 vertebrae) and the hip (femoral neck and total hip). These sites are chosen because they are the most common locations for osteoporosis-related fractures. Your doctor may order a DEXA scan if you are a post-menopausal woman, a man over 65, or if you have risk factors including long-term corticosteroid use, low body weight, a family history of hip fracture, a history of a fragility fracture, or conditions that affect nutrient absorption. Repeat scans are typically ordered every two years to monitor change over time or to assess treatment response.

2. How to Read Your T-Score and Z-Score

Your DEXA report contains two scores. The T-score compares your bone mineral density to the peak bone mass of a healthy 30-year-old adult of the same sex — this is the primary diagnostic score. A T-score of −1.0 or above is normal bone density; between −1.0 and −2.5 indicates osteopenia; and −2.5 or below indicates osteoporosis. The Z-score compares your bone density to the average for someone of your age, sex, and body weight. A Z-score of −2.0 or below is described as “below the expected range for age” and may suggest a secondary cause of bone loss that warrants further investigation — such as long-term steroid use, malabsorption, or thyroid disease.

Always look at the T-score to understand fracture risk, and the Z-score to understand whether your result is unusual for your age. If your T-score and Z-score diverge significantly, raise this with your doctor — it can signal something beyond normal age-related bone loss.

3. What Osteopenia and Osteoporosis Mean for Your Health

An osteopenia result does not mean fracture is inevitable, but it indicates that bone loss has begun and that intervention is appropriate. Studies show that a large proportion of hip fractures occur in people with osteopenia, because there are far more people with osteopenia than osteoporosis in the general population. An osteoporosis result indicates a significantly elevated fracture risk — the WHO threshold of a T-score of −2.5 or below corresponds to approximately 2.5 standard deviations below peak bone mass.

Neither diagnosis determines your treatment on its own. Your doctor will also consider your FRAX score — a validated calculator (available at frax.shef.ac.uk) that combines your T-score with additional risk factors including age, sex, body weight, smoking, alcohol use, family history of hip fracture, steroid use, and rheumatoid arthritis to estimate your 10-year probability of a major osteoporotic fracture. In most guidelines, a 10-year major fracture risk above 20% or hip fracture risk above 3% triggers a recommendation for medication in addition to lifestyle changes.

4. What Causes Low Bone Density?

Common causes of low bone density include age-related hormonal changes (oestrogen decline in menopause, testosterone decline in older men), inadequate calcium and vitamin D intake over many years, physical inactivity, long-term corticosteroid use (prednisolone, dexamethasone), smoking, excessive alcohol consumption, low body weight or a history of eating disorders, and conditions that affect nutrient absorption such as coeliac disease, Crohn’s disease, or gastric bypass surgery. Thyroid disease and inflammatory conditions such as rheumatoid arthritis are also associated with accelerated bone loss.

In Singapore and Southeast Asia, low vitamin D levels are surprisingly common despite high sun exposure — air-conditioned offices and habitual sun avoidance reduce cutaneous D3 synthesis. Low dietary calcium in populations with limited dairy intake is an additional contributing factor, making supplementation especially relevant in this region.

5. How Diet, Exercise, and Lifestyle Affect Bone Density

Bone responds to load — weight-bearing physical activity (walking, jogging, resistance training, dancing) stimulates bone remodelling and slows density loss. Regular resistance training is one of the most effective non-pharmacological interventions for both osteopenia and osteoporosis management. Key dietary and lifestyle recommendations: aim for 1,000mg of calcium per day for adults, and 1,200mg for women over 50 and men over 70 — food sources include dairy products, tofu set with calcium sulphate, canned sardines with bones, and dark leafy greens such as bok choy and kai lan. For vitamin D, 600–800 IU per day is recommended by most guidelines, rising to 1,000–2,000 IU for those with confirmed osteopenia or osteoporosis — discuss the appropriate dose for your situation with your doctor before supplementing. Reducing smoking, limiting alcohol to no more than one to two standard drinks per day, and reviewing medications that cause dizziness (to reduce fall risk) are equally important components of bone health management.

6. Questions to Ask Your Doctor About Your DEXA Results

Bring these questions to your next appointment:

• Is my T-score low enough to require medication, or is lifestyle modification the right first step?
• What is my FRAX 10-year fracture risk, and does it change the treatment recommendation?
• Should I have blood tests to check for secondary causes of bone loss — calcium, vitamin D, parathyroid hormone, thyroid function?
• What calcium and vitamin D dose do you recommend for my specific result?
• Are any of my current medications affecting my bone density?
• If medication is recommended, what are the options, how are they taken, and what are the main side effects?
• How often should I repeat the DEXA scan to monitor progress?
• Should I be referred to a physiotherapist for a bone-safe resistance exercise programme?

7. What Happens Next After a Low Bone Density Result

If your T-score shows osteopenia, your doctor will typically recommend lifestyle changes — calcium and vitamin D supplementation, weight-bearing exercise, fall prevention measures — and schedule a repeat DEXA in two years to monitor progression. If your T-score shows osteoporosis or your FRAX score is high, prescription medication is usually discussed. First-line treatments include bisphosphonates: alendronate (a weekly oral tablet) or risedronate (weekly or monthly oral tablet). For patients who cannot tolerate bisphosphonates, denosumab (a six-monthly subcutaneous injection) is a common alternative. For severe osteoporosis or patients who have already fractured, anabolic agents such as teriparatide (daily injection for up to two years) or romosozumab (monthly injection) may be used.

In Singapore, bisphosphonates are on the Ministry of Health’s Standard Drug List and are Medisave-claimable when used for osteoporosis. In Australia, bisphosphonates are PBS-subsidised with a qualifying DEXA result. In North America, Medicare Part D covers bisphosphonates with an eligible DEXA result. All bisphosphonates must be taken with a full glass of water in the upright position, at least 30 minutes before food or other medications — incorrect administration significantly reduces absorption.

Useful Tools to Prepare

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• Vitamin D3 Supplement (2000 IU) — adequate vitamin D3 supports calcium absorption and bone mineralisation; discuss the right dose with your doctor before taking, particularly if your DEXA result shows osteopenia or osteoporosis
• Doctor Appointment Journal — track your DEXA scores over time, log dietary changes, record exercise habits, and keep your doctor’s treatment recommendations in one organised place

(ASEAN readers) Bone health supplements are also available via Shopee and Watsons.

Medical Disclaimer: This guide is for preparation and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always follow the guidance of your qualified healthcare provider. If you are experiencing a medical emergency, call your local emergency number immediately (Singapore: 995 | Australia: 000 | New Zealand: 111 | USA/Canada: 911). Full disclaimer →