bone density test

Bone Density Test 101: Purpose, Frequency & Types of Bone Scan

Learn about the bone density test and its purpose, how often you should have one and the types of bone scan.

by Nathasha Lee

Bone density tests are important to detect and prevent conditions like osteoporosis, fractures and even cancer. These conditions may not have obvious symptoms and without early detection, might only present themselves when we sustain an injury from a fall. Fractures can lead to hospitalisation and cause lasting impacts on mobility and physical function. One year after sustaining a fracture, 30 percent of people with osteoporosis become partly or fully dependent on others to help them with daily activities. To prevent these negative long-term health consequences, it is important to get a bone scan early on to detect the risk of bone conditions.

What is a bone density test, who needs it and where can you get one? We will answer these questions and more in this article on bone density tests in Singapore.

What is a Bone Scan?

A bone scan, also known as a bone mineral densitometry, is a specialised procedure that uses medical imaging to look at various bones in the skeleton.  A special substance known as a radionuclide will be used during the procedure as a tracer. The tracer will accumulate at the site of abnormal changes, known as “hot spots”, in the bones. This helps doctors detect physical or chemical changes in the bones that can be caused by fractures or conditions like arthritis, osteoporosis, and bone cancer. Bone density tests measure bone mineral density that can let you know if you have brittle bones. They can also help to assess your risk of having fractures in the future.

What is Bone Density?

Bone mineral density, also known as BMD, is a measure of bone loss and this is caused by osteoporosis that causes our bodies to lose bone tissue. While the rate at which our body replaces bone tissue that has been lost starts to slow down in our 20s, many people reach their peak bone mass in their 30s. The lower your peak bone mass is, the higher the chance of developing osteoporosis when you are older.

When our bodies lose bone tissue, our bones decrease in mass and become less dense; they become brittle and will break more easily, making us more likely to sustain fractures when we fall. Bone density tests can also measure the progress of treatment for conditions which cause bone loss. 

Why Is a Bone Density Test Done?

A bone mass density test is done when you have encountered bone injuries or are at risk of conditions that cause bone loss. People with the following conditions are at risk and should consider doing a bone mineral density test:

  • Those who have had a fracture after a minor fall or injury.
  • Those who have had a decrease in height following a fracture of a back vertebra (bone).
  • Those with conditions that increase one’s risk of developing osteoporosis, like rheumatoid arthritis, thyroid diseases, long-term kidney and liver disease, and coeliac disease (a condition involving the immune system which makes someone unable to digest gluten).
  • Women who have gone through menopause. Menopause causes a decrease in the hormone oestrogen which causes bone tissue to recover at a slower rate.
  • People who have taken steroid tablets for at least three months.
  • People who smoke and/or drink frequently. Smoking and high alcohol consumption prevents the body from absorbing calcium, which is needed to maintain strong and healthy bones.
  • People with a Body Mass Index (BMI) of less than 19, which is considered very underweight.
  • People with family members who have broken their hip before.

Other potential symptoms of osteoporosis include persistent lower back pain and shortness of breath, which happens when our vertebral discs slip and exert pressure on our lungs. You should pay attention to these symptoms and discuss them with your doctor to see if you require a bone mineral density scan.

How Often Do I Need to Go For a Bone Density Test?

How often you need to go for a bone mineral density test depends on your age and other risk factors. Most people above the age of 65 do not need to take a bone scan if they have a low risk of getting bone fractures, exercise regularly and obtain a lot of vitamin D and calcium. Our bodies produce vitamin D from moderate exposure to sunlight and obtain it from foods such as mushrooms, fatty fish like salmon and mackerel, and egg yolks. For women over 65 and men over 70 years of age, a bone density test is necessary if they have a fracture of moderate severity to assess the extent of damage to the bone.

Younger people aged 50 to 59 should consider getting a bone density test if they have one or more of the risk factors discussed above in the previous section. You may need a follow-up test after a few years depending on the results in your first test. If you have a low T-score of between -1.5 and -2.49 on your first bone mineral density test, more frequent testing may be required.

Types of Bone Density Tests

There are two types of bone density tests which differ based on which parts of the body are being scanned. One type of test is done with a central DEXA (dual-energy X-ray absorptiometry) machine to scan for abnormalities in the hip and the spine. Measuring the bone density in the hip and spine helps to predict the risk of fractures in bones at other parts of the body. Another is done with a periphery DEXA machine that measures bone density in the lower arm, heel, wrist, or fingers. Such a scan is known as a peripheral DEXA scan and can be found at smaller medical offices that might not have equipment to do a central DEXA scan.

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Risks and Limitations of Bone Density Tests

A bone density test cannot provide a guaranteed indication that you have osteoporosis or not. If you have a peripheral DEXA scan, you cannot accurately compare them to the results of a central DEXA scan as they scan different parts of the body. To further determine your risk for conditions that affect bone loss, you might want to get both a central DEXA and a peripheral DEXA scan.

Items like metal jewellery, body piercings, and metallic implants may interfere with the results of your bone scan. Try to remove piercings and jewellery before you go for a scan. Healed bone fractures may also appear in the results of the scan. Barium X-ray scans, which are used to measure parts of the gastrointestinal tract like the stomach and oesophagus, will also interfere with scan results. If you have taken a barium X-ray, you are required to wait 10 to 14 days before going for a bone density scan.

Because a bone density scan is a radiology procedure, you will be exposed to small amounts of radiation during the scan. These small levels of radiation are safe for most people. However, repeated exposure to radiation might increase your chance of developing cancer. If you have gotten many X-ray scans before and are concerned about the increased cancer risk, please speak to your doctor.

Radiation exposure may also affect the health of your child if you do a bone mineral density scan while pregnant. If you are concerned for your child’s safety let your healthcare provider know.

Preparing for a Bone Scan

When you arrive at the location where you will take your scan, your doctor will explain what will happen during the procedure and ask if you have any questions. They will also ask about your medical history and other medications you are taking. This is a good time for you to let your healthcare providers know about your concerns, such as if you are pregnant or have other conditions that might impact the results of the test.

You will be asked to lie down on a couch and stay still while an X-ray detector passes over your body. There is no need for you to fast before the procedure. The scan will take between 15 to 25 minutes.

The scan typically takes two to three hours and is painless. You can return home as soon as the scan has been completed and you don’t have to worry about the tracer staying in your body as it will be passed out as urine the next day.

Understanding the Results of Your Bone Density Test

Bone density results appear as T-scores and as z-scores. The z-score compares your bone mass density to the average of people of the same gender and age group. T-score shows how much bone mass you have left compared to the average bone mass of a young healthy adult. A T-score that is between 1 to -1, or within one standard deviation, indicates that you have a healthy bone mass and a T-score of -2.5 or lower indicates that someone can be diagnosed with osteoporosis and require medication. With each increase in standard deviation below the T-score, your risk of bone fractures is doubled. For example, if your T-score is -2 you are twice as likely to sustain bone fractures as someone with a T-score of -1.

If you have a low T-score, you might proceed to discuss treatment options with your healthcare provider. Your doctor might prescribe medication to promote bone cell growth and increase bone mass density. Getting more vitamin D to build stronger bones, doing exercises to improve balance, and removing hazards in your home to prevent falls might also be necessary to reduce your risk of having a serious injury in the future.

Where Can I Take a Bone Density Test in Singapore?

You can request a bone density test at the radiology departments of most hospitals and medical centres around Singapore. Before you can book an appointment to take a bone density test you need a referral from your doctor. Most appointments are held in the morning. A bone mineral density test costs around $150. The cost of a bone mineral density test can be claimed under MediSave as you can claim a maximum of $300 a year to cover the cost of scans to diagnose your medical condition.

We hope that this article has let you become more well-informed about what a bone scan involves and how you can get one in Singapore. Our Homage Care Pros can further support you in your healthcare journey by providing the expertise needed to help you manage your condition. Our Care Pros are trained to help you with physiotherapy to recover mobility after an injury, guide you through exercises to improve your physical function, and facilitate transport to medical appointments. We can also help you conduct general health screenings at home to check for other conditions. Use our app to arrange for one of our Care Pros to come to your doorstep in just hours so that you can receive care from the comfort of your home.

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References
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About the Writer
Nathasha Lee
Nathasha Lee is a final-year Anthropology major at Yale-NUS College. She hopes her writing can make a positive difference in the lives of readers, no matter how small. In her spare time, she enjoys making art, listening to podcasts, and drinking lots of tea.
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