Bone Mineral Density Scan (DEXA): Everything You Need to Know

What is a bone mineral density scan (DEXA)?

A bone mineral density (BMD) test is a medical examination that measures the amount of minerals, primarily calcium, in your bones. This test helps evaluate bone strength and the risk of fractures, especially in individuals at risk of osteoporosis – a medical condition that causes bones to become weak, brittle, and more prone to fractures – or other bone-related conditions.

The most common and reliable method for measuring bone density is the DEXA scan (dual-energy X-ray absorptiometry). This scan uses low-dose X-rays to assess bone density in specific areas of the body, usually the hip, spine, or wrist, where fractures are most likely to occur. By detecting even small reductions in bone mass, a DEXA scan allows doctors to diagnose osteoporosis early and recommend appropriate treatment or lifestyle changes to improve bone health.

Who should get a DEXA?

A DEXA scan is recommended for individuals at higher risk of osteoporosis or bone loss. It helps detect early signs of weakening bones and allows for preventive measures to reduce fracture risks. You may need a DEXA scan if you fall into one of the following categories:

• Postmenopausal women:

  • Especially those at increased risk of osteoporosis due to hormonal changes after menopause.

• Men over 70 years old:

  • Bone density naturally decreases with age, making osteoporosis a concern for older men.

• Individuals with a history of fractures:

  • Particularly those who have experienced low-impact fractures (for example, breaking a bone from a minor fall or injury).

• People with underlying risk factors, including:

  • A family history of osteoporosis or fractures.

  • Long-term use of corticosteroids (such as prednisone), which can weaken bones.

  • Medical conditions such as rheumatoid arthritis, thyroid disorders, or gastrointestinal diseases that affect nutrient absorption.

• Individuals with low body weight: 

  • Those who are underweight or have a small frame may have naturally lower bone mass and a higher risk of fractures.

• People with lifestyle factors that contribute to bone loss:

  • Smoking

  • Excessive alcohol consumption

  • Poor dietary intake of calcium or vitamin D

Early detection of low bone density can help prevent osteoporosis and fractures through lifestyle changes, medication, or dietary improvements. If you have any of these following risk factors, request an appointment about whether a DEXA scan is right for you.

Why do we need a DEXA scan?

A DEXA scan is the most reliable and accurate method for measuring bone mineral density. It helps assess bone health and detect conditions like osteopenia and osteoporosis, which can increase the risk of fractures and other complications. Here’s why a DEXA scan is important: 

1. Early detection of osteoporosis:

   • Osteoporosis is often called a silent disease because it develops gradually without symptoms until a fracture occurs.

2. Assessing fracture risk:

   • Low bone density increases the likelihood of fractures, especially in areas like the hip, spine, and wrist.

3. Monitoring bone health over time:

   • It helps track changes in bone density, making it useful for people undergoing osteoporosis treatment or lifestyle modifications to improve bone strength.

4. Evaluating the impact of medical conditions and medications:

   • Certain medical conditions (such as rheumatoid arthritis, thyroid disorders, and gastrointestinal diseases).

   • Long-term use of medications like corticosteroids can contribute to bone loss.

How to prepare for a DEXA scan?

The DEXA scan is simple and doesn't need any special preparation. However, following these guidelines can help ensure accurate results:

1. Dress comfortably: 

   • Wear loose-fitting clothing without metal (such as zippers, buttons, or belts), as metal objects can interfere with the scan. 

   • You may also be asked to remove jewellery or accessories before the test.

2. Inform the technician if you’re pregnant:

   • Although a DEXA scan uses very low-dose X-rays, it’s important to let the technician know if you are pregnant or could be pregnant. 

   • Your doctor may recommend postponing the test or using an alternative method to assess bone health.

3. Avoid calcium supplements: 

   • You may be asked not to take calcium supplements for at least 24 hours before the test. High calcium levels in the body could affect the accuracy of the results.

4. Mention any recent imaging tests:

   • If you’ve had a contrast dye test, such as a CT scan, MRI, or barium exam, inform your doctor. 

   • These procedures may interfere with the BMD test results, and you might need to wait a few days before undergoing a DEXA scan.

How does a DEXA scan work?

During the test, you will lie on a padded table while a scanning arm moves over your body, using a low-dose X-ray to assess bone density at specific sites, typically the lumbar spine, hip, and forearm—areas most prone to fractures. The procedure is non-invasive, painless, and does not require injections, making it a comfortable experience. It usually takes 10 to 30 minutes to complete, and since the radiation exposure is minimal, the scan is considered very safe. Once the test is done, the results will help your doctor evaluate your bone health and determine if any preventive measures or treatments for osteoporosis are needed.

Understanding bone density measurements test results 

The results of the test are typically presented using two key measures: the T-score and the Z-score.

The T-score compares your bone density to that of a healthy young adult of the same sex. It helps determine if your bone density is within a normal range or if you have signs of bone loss:

• Normal: 

  • T-score above -1.

• Osteopenia (low bone mass): 

  • T-score between -1 and -2.5.

• Osteoporosis: 

  • T-score below -2.5, indicating significant bone loss and an increased risk of fractures.

The Z-score compares your bone density to others of the same age, sex, and body size. A Z-score significantly lower than average may suggest an underlying medical condition contributing to bone loss, such as hormonal imbalances or certain diseases.

Bone mineral density test (DEXA) prices in Singapore

The cost of a Bone Mineral Density (BMD) test in Singapore varies depending on the healthcare provider, type of scan, and whether additional services such as consultations or follow-up assessments are included. Prices can range from affordable options at community health centres to higher rates at private clinics and specialist facilities. 

Generally, prices range from as low as $29 for subsidised screenings to $379 for specialist consultations combined with the test.

Some clinics and health centres offer subsidised rates for eligible individuals, making BMD tests more accessible, particularly for seniors or those with government healthcare cards. In private healthcare settings, the cost may be higher, especially if the test is bundled with specialist consultations or additional diagnostic services. For those seeking a basic DEXA scan, mid-range pricing is available at many medical centres, while comprehensive screening packages that include blood tests and specialist evaluations tend to cost more.

Where can I have a bone density scan in Singapore?

There are several healthcare facilities in Singapore that offer DEXA scans for assessing bone mineral density and body composition. These scans are commonly available at hospitals, specialist clinics, radiology centres, and health screening providers.

Many private hospitals and medical centres offer DEXA scans as part of their diagnostic imaging services. Some general practitioners and specialist clinics, particularly those focusing on orthopaedics, endocrinology, and women's health, also provide bone density assessments. Additionally, certain health screening centres include DEXA scans as part of their osteoporosis screening packages.

For those looking for more affordable options, government-subsidised health facilities and community healthcare providers may offer DEXA scans at reduced rates for eligible individuals, such as seniors or those with healthcare subsidies.

At Thomson Medical, we offer comprehensive DEXA bone mineral density scans to accurately assess bone health and detect early signs of osteoporosis. If you have risk factors for bone loss, request an appointment with us and take a proactive step towards better bone health.

Risks with a bone mineral density test (DEXA)

DEXA scans are considered very safe with minimal risks. However, there are a couple of factors to be aware of:

• Radiation exposure: 

  • The amount of radiation used in a DEXA scan is extremely low—much lower than that of a standard X-ray. The risk from this exposure is minimal and not considered harmful for most individuals. 

  • However, if you are pregnant or suspect you might be, inform your doctor before the test.

• Discomfort: 

  • The test is non-invasive and painless, but some people may find lying still in certain positions slightly uncomfortable. This discomfort is temporary and typically lasts only for the duration of the scan, which is about 10 to 30 minutes.

FAQs

What is considered a normal bone mineral density?

A normal bone mineral density is indicated by a T-score above -1.This value means your bone density falls within the expected range for a healthy young adult of the same sex, suggesting strong and healthy bones with a low risk of fractures.

What can a bone density test (DEXA) diagnose?

A DEXA scan primarily confirms the diagnosis of osteoporosis and osteopenia by measuring bone mineral density and assessing fracture risk. It can also evaluate body composition, including fat and muscle mass, in some cases. Doctors use it to detect broken bones or bone loss due to ageing, medical conditions, or long-term medication use, helping guide treatment and prevention strategies. Moreover, it helpsmonitor your bones' response to treatment for osteoporosis or osteopenia.

Is the DEXA scan painful?

A bone density test, such as a DEXA scan, is completely painless. The procedure is non-invasive and does not require any injections or discomfort.

How long does a DEXA scan take?

A DEXA scan is a quick procedure, typically taking 10 to 30 minutes to complete. The exact duration depends on the areas being scanned, but the test is non-invasive, painless, and requires minimal preparation.

Is a DEXA scan similar to an MRI?

No, a DEXA scan is not like an MRI. A DEXA scan uses low-dose X-rays to measure bone mineral density, while an MRI uses magnetic fields and radio waves to create detailed images of soft tissues and organs. A DEXA scan is quick, painless, and focused on bone health, whereas an MRI is used for diagnosing a wider range of conditions.

Who should avoid a DEXA scan?

While a bone density scan is safe for most people, it may not be suitable for:

• Pregnant women: 

  • Due to low-dose X-ray exposure, it is generally avoided unless absolutely necessary.

• Individuals with recent contrast imaging: 

  • If you’ve recently had a CT scan, MRI with contrast, or a barium study, the results may be affected, and you may need to wait before undergoing a DEXA scan.

• People with metal implants near the scan area: 

  • Metal objects, such as hip replacements, may interfere with accuracy.

• Those unable to remain still: 

  • The test requires staying still for a few minutes to ensure precise results.

What should you avoid during a DEXA scan?

To ensure accurate results, avoid the following before and during a DEXA scan:

• Calcium supplements: 

  • Refrain from taking calcium supplements 24 hours before the scan, as they may affect the readings.

• Metal objects: 

  • Remove jewellery, belts, and clothing with metal zippers or buttons, as metal can interfere with the scan.

• Recent contrast imaging: 

  • If you have had a CT scan, MRI with contrast, or barium X-ray recently, inform your doctor, as it may impact the results.

• Excessive movement: 

  • Stay still during the scan to prevent blurring and ensure precise measurements.

What should you avoid drinking before a DEXA scan?

Before a DEXA scan, it is best to avoid drinks high in calcium, such as milk, fortified juices, or calcium supplements, for at least 24 hours prior to the test. Excess calcium in the bloodstream may affect the accuracy of measuring bone mineral density

While water, coffee, and tea (without added calcium or supplements) are generally fine, it’s best to follow any specific guidelines provided by your healthcare provider to ensure accurate results.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.