Bone Density Scan
A bone density scan, also known as a dual-energy X-ray absorptiometry (DEXA) scan or bone densitometry, is a test that helps to estimate the density of the bone by measuring the amount of mineral matter per square centimetre of bone. It is a quick, painless and non-invasive screening procedure, using a low dose of radiation.
Bone mineral density (BMD) is commonly used to diagnose osteopenia and osteoporosis to predict individual fracture risk. Osteopenia and osteoporosis are conditions characterised by brittle bones, largely seen in the elderly population.
Stages of Osteoporosis:
Who needs to have a bone density scan?
Women aged 65 or older should have a bone density scan. Women in this age group are at high risk for losing bone density, which can lead to fractures.
Although osteoporosis can affect anyone at any age, postmenopausal women are particularly at risk because oestrogen level declines after the menopause, resulting in a decrease in bone density. Bone density testing is strongly recommended if you are a post-menopausal woman and not taking oestrogen.
You may also be at risk for low bone density if you:
- Have a very low body weight or a body mass index (BMI) of less than 21
- Have lost a half inch or more in height within one year
- Have had one or more fractures after the age of 50
- Have been taking oral glucocorticoids for 3 months or more
- Are a man over the age of 70
- Are a woman who has had an early menopause, or had the ovaries removed at a young age (before 45) and have not had hormone replacement therapy (HRT)
- Have clinical conditions associated with bone loss, such as rheumatoid arthritis, chronic kidney or liver disease.
- Have a family history of osteoporosis or hip fractures
Other risk factors include:
- Lack of physical activity
- Smoking cigarettes
- Heavy drinking
- Having a thyroid condition, such as hyperthyroidism.
- Having a parathyroid condition, such as hyperparathyroidism.
- Not getting enough calcium and vitamin D in your diet
How should you prepare for a bone density scan?
Virtually no preparation is needed.
🥗 On the day of the scan you may eat normally.
👕 You should wear loose, comfortable clothes, avoiding garments that have zips, poppers, bra closures, belts or buttons made of metal. Objects such as keys or wallets that would be in the area being scanned should be removed. Remove jewellery, removable dental appliances, eyeglasses, and any metal objects or clothing that might interfere with the X-ray images.
💻 Inform your doctor if you have recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan, nuclear medicine test or radioisotope scan. You may have to wait 10 to 14 days before undergoing a bone density scan.
How does it work?
|During a bone density scan, special types of photon beams from the machine passes through your body.
|Some energy is absorbed by the bone and soft tissue while some travels through your body. The amount of radiation is very minimal, similar to daily background radiation.
Special detectors in the DEXA machine measure how much energy passes through your bones and soft tissues, and this information is sent to a computer.
Your bone density scan results will be compared with that expected for a healthy adult of your own age, gender and ethnicity.
What happens in a bone density scan?
- You will be conscious throughout the procedure
- You will be asked to remove all jewellery
- The scan requires no sedation, injection or medication
- The test will be performed with you lying down
- It should take about 15 to 30 minutes
- Just follow the instructions given by the radiographer (the technical specialist carrying out the scan)
- You will receive a printed copy of the report during your doctor’s consultation
How safe are bone density scans?
Since bone density scans use a much lower dose of radiation compared to standard X-rays, they are very safe. In spite of this, bone density scans are not recommended for pregnant women.