What is a DEXA scan?
A DEXA (Dual-Energy X-ray Absorptiometry) scan, sometimes referred to as a dexabone scan when specifically evaluating bone health, is a non-invasive medical imaging test that measures bone mineral density (BMD). This advanced technology uses two low-dose X-ray beams with different energy levels to distinguish between bone and soft tissue, providing highly accurate measurements of bone density. Unlike conventional X-rays that only detect bone fractures after they occur, DEXA scans can identify weakening bones long before they break. The procedure is considered the gold standard for diagnosing osteoporosis and assessing fracture risk. The term DEXABONE emphasizes the specific application of this technology for skeletal assessment, distinguishing it from other uses of DDXA such as body composition analysis. The scan typically focuses on the hip and spine—the most common sites of osteoporotic fractures—though peripheral devices can measure the wrist or heel when central scanning isn't available.
Why are DEXA scans performed?
DEXA scans are primarily performed to detect low bone density before it leads to fractures, diagnose osteoporosis, and monitor the effectiveness of treatment. Osteoporosis is often called a "silent disease" because bone loss occurs without symptoms until a fracture happens. In Hong Kong, approximately 50% of postmenopausal women and 20% of men over 50 will experience an osteoporotic fracture in their remaining lifetime. These fractures, particularly hip fractures, can have devastating consequences: about 20% of elderly hip fracture patients in Hong Kong die within one year due to complications, and many others experience permanent disability. DEXABONE scanning helps identify at-risk individuals early, allowing for preventive measures. Additionally, these scans are used to monitor bone density changes in patients undergoing long-term steroid therapy, those with endocrine disorders (like hyperthyroidism or Cushing's syndrome), and individuals with conditions affecting nutrient absorption (such as celiac disease or inflammatory bowel disease). The information gathered from a DEXABONE assessment provides crucial data for developing personalized bone health management plans.
Who should get a DEXA scan?
Several population groups benefit from DEXABONE scanning based on established medical guidelines. The Hong Kong Osteoporosis Foundation recommends DEXA scans for all women aged 65 and older and men aged 70 and older, regardless of risk factors. Younger postmenopausal women and men aged 50-69 with clinical risk factors should also undergo screening. These risk factors include a personal history of fracture as an adult, parental history of hip fracture, current cigarette smoking, low body weight (less than 57kg or 125lbs), long-term use of glucocorticoid medications (such as prednisone), rheumatoid arthritis, excessive alcohol consumption (three or more drinks daily), and secondary causes of bone loss. Additionally, individuals with specific medical conditions including hyperparathyroidism, organ transplantation, eating disorders, or premature menopause (before age 45) should consider DEXABONE assessment. For context, Hong Kong's Hospital Authority reports that approximately 30% of postmenopausal women in the territory have osteoporosis, highlighting the importance of targeted screening.
What to expect before the scan
Preparation for a DEXABONE scan is straightforward but requires attention to specific details to ensure accurate results. Typically, you'll receive instructions from your healthcare provider or the imaging center when scheduling your appointment. Unlike many diagnostic tests, you usually don't need to fast or follow special dietary restrictions before a DEXA scan. However, you should inform your doctor about any recent medical tests involving contrast materials or radioactive tracers, as these might interfere with results if performed within a week of your DEXABONE scan. You'll be asked to complete a questionnaire about your medical history, risk factors, and medications. The technologist will verify your information before the procedure and may take your height and weight measurements to help interpret the results. It's crucial to reschedule your appointment if you might be pregnant, as although radiation exposure is minimal, X-rays are generally avoided during pregnancy unless absolutely necessary.
Medications and supplements to avoid
While most medications don't interfere with DEXABONE scanning, certain supplements and drugs containing calcium can artificially alter bone density measurements. You should avoid taking calcium supplements for at least 24 hours before your scan, as undigested calcium tablets in your digestive system might be detected by the scanner and potentially skew results. This includes calcium carbonate, calcium citrate, and multivitamins containing calcium. However, continue taking prescription medications unless specifically instructed otherwise by your doctor. If you've recently had a barium study (such as a barium swallow or enema) or received intravenous contrast material for a CT scan or MRI, you should wait at least 7-14 days before undergoing your DEXABONE scan, as these substances can remain in the body and affect accuracy. Always provide your doctor with a complete list of all medications and supplements you're taking, including dosages and frequency.
What to wear
Choosing appropriate clothing for your DEXABONE scan can streamline the process and improve comfort. Wear loose, comfortable clothing without metal fasteners, zippers, buttons, or hooks in the area being scanned—typically the lumbar spine and hips. Many facilities will provide a gown, but you can optimize your experience by wearing athletic wear or comfortable pants with an elastic waistband. Avoid wearing belts, jewelry, or other metal accessories, as metal can interfere with the X-ray beams and compromise image quality. You'll likely be asked to remove eyeglasses, removable dental appliances, and any metal objects from your pockets. Some imaging centers may ask you to change completely into a hospital gown to ensure no interfering materials are present during the DEXABONE procedure. Wear comfortable shoes as you'll need to lie on the scanning table but won't need to walk around extensively during the appointment.
What happens during the scan
The DEXABONE scanning procedure is painless, non-invasive, and typically conducted by a radiologic technologist specially trained in bone densitometry. You'll lie on a padded table while a mechanical arm passes over your body, emitting low-dose X-rays. For the standard central DEXA scan, you'll position yourself on your back with your legs supported by a positioning device—typically a foam block that rotates your hips inward to properly align the femoral neck for measurement. The technologist will ensure you're comfortable and properly positioned before leaving the scanning room to operate the equipment from an adjacent control room. You'll need to remain still during the actual scanning process, which typically involves two different measurements: one of your lumbar spine (lower back) and one of your hip. The entire DEXABONE procedure is conducted without any injections, invasive procedures, or discomfort beyond lying still on a firm surface. Communication systems allow you to speak with the technologist throughout the process if needed.
How long does the scan take?
The actual scanning time for a DEXABONE procedure is remarkably quick, typically taking between 10 and 20 minutes depending on the equipment used and the number of sites being measured. A standard central DEXA scan measuring both the spine and one hip usually requires approximately 15 minutes of actual scanning time. However, you should plan to spend 30-45 minutes at the imaging facility to account for check-in procedures, changing clothes if necessary, positioning on the scanning table, and verification of image quality. Newer DEXABONE systems with faster scanning capabilities can complete the procedure in as little as 3-5 minutes per site. Peripheral devices that measure the wrist, heel, or finger are even quicker, often taking less than 5 minutes total. The efficiency of modern DEXABONE technology makes it an accessible screening tool that can be easily incorporated into routine healthcare appointments without significant disruption to your schedule.
Is the scan safe?
DEXABONE scanning is extremely safe with minimal radiation exposure—significantly lower than many other radiographic procedures. The effective radiation dose from a central DEXA scan is approximately 1-10 microsieverts (μSv), which is less than the daily background radiation exposure everyone experiences from natural sources. To put this in perspective, a chest X-ray delivers about 100 μSv, a mammogram about 300 μSv, and a CT scan of the abdomen can deliver up to 10,000 μSv. The radiation exposure from a DEXABONE scan is roughly equivalent to the exposure during a transcontinental flight or less than one-tenth of the radiation received from a standard chest X-ray. The benefits of early detection of osteoporosis far outweigh this minimal risk. The procedure has no known long-term side effects, and the equipment doesn't produce the enclosed feeling that some people experience with MRI machines, making it suitable for those with claustrophobia.
Understanding T-scores and Z-scores
DEXABONE results are reported using two primary measurements: T-scores and Z-scores. The T-score is the most important value for diagnosing osteoporosis in postmenopausal women and men aged 50 and older. It compares your bone density to that of a healthy young adult of the same sex, measured in standard deviations (SD) above or below the average. A T-score of -1.0 or above is considered normal bone density. A T-score between -1.0 and -2.5 indicates low bone mass (osteopenia), while a T-score of -2.5 or below indicates osteoporosis. The Z-score compares your bone density to what's expected for someone of your same age, sex, weight, and ethnic origin. This measurement is particularly useful for children, premenopausal women, and men under 50. A Z-score below -2.0 suggests that something other than normal aging is causing bone loss and may warrant further investigation. Both scores are crucial components of a comprehensive DEXABONE assessment, providing different perspectives on your bone health status.
Normal, osteopenia, and osteoporosis ranges
DEXABONE results categorize bone density into three diagnostic classifications based on T-scores:
- Normal bone density: T-score of -1.0 or higher. This indicates your bone density is within 1 standard deviation of the average peak bone mass of a healthy young adult. Approximately 68% of the population falls within this range. Individuals with normal DEXABONE results typically have low fracture risk and are generally advised to maintain their bone health through adequate calcium intake, vitamin D, and regular weight-bearing exercise.
- Osteopenia (low bone mass): T-score between -1.0 and -2.5. This indicates bone density that is below normal but not yet in the osteoporosis range. In Hong Kong, studies suggest that about 40% of postmenopausal women have osteopenia. This condition represents a warning sign that bone loss is occurring, and intervention can help prevent progression to osteoporosis. DEXABONE monitoring every 1-2 years is often recommended for this group.
- Osteoporosis: T-score of -2.5 or lower. This indicates significantly low bone density with substantially increased fracture risk. Severe or established osteoporosis is diagnosed when T-scores are this low and fractures have already occurred. In Hong Kong, approximately 30% of postmenopausal women and 15% of men over 65 meet criteria for osteoporosis based on DEXABONE assessments.
Factors affecting bone density
Multiple factors influence bone density measurements obtained through DEXABONE scanning. Some factors are modifiable, while others are fixed. Non-modifiable risk factors include:
- Advancing age (bone loss accelerates after age 50)
- Female sex (women have lower peak bone mass and accelerated loss after menopause)
- Family history of osteoporosis or hip fracture
- Ethnicity (Caucasian and Asian populations have higher risk)
- Small body frame and low body weight
- Nutritional status (inadequate calcium and vitamin D intake)
- Physical activity level (especially weight-bearing and resistance exercises)
- Smoking (reduces blood supply to bones and decreases calcium absorption)
- Excessive alcohol consumption (more than 2 drinks daily)
- Certain medications (long-term corticosteroid use, some anticonvulsants)
- Medical conditions (rheumatoid arthritis, hyperthyroidism, malabsorption syndromes)
- Hormonal imbalances (early menopause, low testosterone in men)
Discussing results with your doctor
After receiving your DEXABONE results, schedule a follow-up appointment with your doctor to discuss their significance and develop an appropriate management plan. Come prepared with questions about your T-score and Z-score, what they mean for your fracture risk, and whether additional testing might be needed. Ask about how your results compare to previous scans if you've had them, and what rate of bone loss might be expected without intervention. Discuss your personal risk factors and how they might be modified. Inquire about the frequency of follow-up DEXABONE scans recommended for your situation—typically every 1-2 years for those being treated for osteoporosis or with osteopenia and higher risk, or every 2-5 years for those with normal bone density or stable osteopenia with low fracture risk. Your doctor should explain whether medication is recommended based on your DEXABONE results, overall health, and fracture risk assessment tools like FRAX® (Fracture Risk Assessment Tool), which incorporates additional risk factors beyond bone density.
Treatment options for low bone density
Treatment recommendations based on DEXABONE results vary depending on the severity of bone loss and individual fracture risk. For osteopenia, treatment often focuses on lifestyle modifications and may include calcium and vitamin D supplementation if dietary intake is insufficient. When osteoporosis is diagnosed, several medication options are available:
- Bisphosphonates: The most commonly prescribed medications (alendronate, risedronate, ibandronate, zoledronic acid) that slow bone breakdown.
- RANK ligand inhibitors: Denosumab injections given every six months that reduce bone breakdown.
- Anabolic agents: Teriparatide and abaloparatide daily injections that stimulate new bone formation, reserved for severe osteoporosis.
- Romosozumab: A newer medication that both increases bone formation and decreases bone breakdown, administered monthly for one year.
- Hormone-related therapy: Estrogen therapy for postmenopausal women or testosterone for men with low levels.
- SERMs: Selective Estrogen Receptor Modulators like raloxifene that provide estrogen-like benefits to bone without some risks.
Lifestyle changes to improve bone health
Regardless of your DEXABONE results, several lifestyle modifications can support bone health and potentially slow bone loss. Nutrition plays a crucial role: ensure adequate calcium intake (1000-1200 mg daily for most adults) through dietary sources like dairy products, fortified plant milks, leafy greens, sardines with bones, and tofu processed with calcium sulfate. Vitamin D (600-800 IU daily for adults, more for deficiency) is essential for calcium absorption and can be obtained from sunlight exposure, fatty fish, fortified foods, and supplements. Regular weight-bearing exercises (walking, jogging, dancing, tennis) and resistance training (weights, resistance bands) at least 3-4 times weekly stimulate bone formation. Balance exercises (tai chi, yoga) can reduce fall risk. Avoid smoking and limit alcohol to no more than one drink daily for women and two for men. Fall prevention strategies include removing home hazards, improving lighting, installing grab bars, and reviewing medications that might cause dizziness. These approaches complement medical treatments and can significantly impact long-term bone health outcomes.
Taking control of your bone health
Understanding your DEXABONE results empowers you to take proactive steps toward maintaining skeletal strength and preventing fractures. Bone health is a lifelong commitment that requires attention to nutrition, physical activity, and regular monitoring when indicated. Remember that a diagnosis of osteopenia or osteoporosis isn't inevitable—many interventions can slow, stop, or even reverse bone loss when implemented appropriately. Work collaboratively with your healthcare provider to develop a personalized plan based on your DEXABONE results, risk factors, and personal preferences. Stay informed about new developments in bone health management, as research continues to advance our understanding of osteoporosis prevention and treatment. By taking ownership of your bone health through informed decisions and consistent action, you can significantly reduce your fracture risk and maintain mobility and independence throughout your life. Regular follow-up with your healthcare provider and appropriate DEXABONE monitoring will help ensure your bone health strategy remains effective over time.
