What is a Bone Density Test? | Types of Bone Density Tests | Who Should Get One? | How it Works | Radiation Exposure |Considering Bone Density Treatments And How to Read Your Results | Measure Your Progress | Care and Treatment for Osteoporosis | DEXA Scan Clinic Directory | Common Questions About Bone Density Testing
What is a “Bone Density Test?”
A Bone density test, also known as a DEXA stands for Dual Energy X-Ray Absorptiometry and is the most widely used test to measure bone mineral density. It is a testing machine that measures the density of your bones. The calculation is done knowing that the denser the bone, the less X-rays pass through. Usually the more dense your bone, the stronger it is, and the less likely it is to fracture.
If you’ve ever had an x-ray, the process is very similar.
A DEXA machine uses low-energy X-rays and sends two different sources (thus the ‘dual’ part) through the bone in question. Bone blocks some of the X-rays. The more dense your bone is, the less X-rays pass through to the detector. By Two different X-ray sources rather than one are used to double the accuracy in measuring your bone density.
The amount of X-rays that comes through the bone from each of the two X-rays is sent to a computer which calculates an average score of the density of your bone.
A DEXA scan is more accurate than regular x-rays or CAT scans and requires less radiation exposure. See more about radiation and DEXA scans, below.
Types of Bone Density Tests
- Central DEXAs look at your whole skeleton, paying special attention to your spine and hips. These machines are usually found in hospitals and medical centers, but there are some in doctors’ offices.
- Peripheral DEXAs are smaller, and focus on your extremities, like your fingers, ankles and wrists. You often find peripheral DEXA machines in a doctor’s office or smaller medical exam facility, though sometimes you see them at health fairs or even at bigger shopping malls!
Both the Central and the Peripheral tests are done on an “out-patient” basis – that means no long stay in the hospital.
The Central DEXA (by the way, the test is sometimes referred to as “DXA” as well as DEXA) takes less than 30 minutes, and the Peripheral DEXA lasts about 10 minutes.
In the Central DEXA, you lie comfortably on a padded table. No need to remove your clothes – just make sure there are no zippers that might block the x-rays of your hips and spine.
Below the bed is the x-ray generator, and above you is the imaging device.
The person who performs the test will usually place a small pillow to support your legs. This results in your spine lying flat on the table – the better to get a great image. Also, you may find your foot placed in a brace – this helps keep you hip nice and still during the procedure.
The technician will help you prepare, then walks behind a protective wall. (Remember, the x-ray dose is teeny-tiny, but this person takes dozens of these x-rays every day, so they need extra protection.)
The imaging detector will pass slowly over your body. During this time – and your tech will give you warning – you need to hold your breath – but just for a few seconds.
This will produce an image that looks like this:
The peripheral bone density tests are simpler.
You place your finger, hand, forearm or foot in a small device that obtains a bone density reading within a few minutes.
There is an additional procedure called Lateral Vertebral Assessment (LVA). This is done at many centers. LVA is a low-dose x-ray examination of the spine to screen for vertebral fractures and is also performed on the DEXA machine.
The LVA test adds only a few minutes to the Central DEXA procedure.
The DEXA bone density test usually takes less than 30 minutes, depending on the equipment used and the parts of your body being examined.
The technician may ask you to complete a quick questionnaire. This helps the doctor determine if you have osteopenia, osteoporosis or some other medical condition.
Your DEXA results will reveal your BMD – Bone Mass Density – simply, how healthy are your bones. The report also lists your T-score and Z score.
Who Should Get a DEXA Scan?
DEXA scans are now the best method of diagnosing and monitoring osteopenia and osteoporosis. The National Osteoporosis Foundation’s guidelines state that women over 65, younger post menopausal women who have any osteoporosis risk factors and aging men with any osteoporosis risk factors should be tested with DEXA scans. (1)
There are numerous risk factors that can increase your risk of osteoporosis. Below are a few for you to watch out for. If you say, “That’s me” to two or more on this list, it might be a good idea to ask your doctor about a DEXA scan.
- Your gender: Women are 2x more likely to develop osteoporosis than men. Due to menopause, estrogen decreases sharply, which accelerates bone loss. For example, in the five to seven years following menopause, a woman can lose up to 20% of her bone density.
- Age: In our lifetime, we increase bone mass from childhood to about our mid-thirties at which time we reach our peak bone mass. From then on, we lose about 1% of our bone every year.
- Lack of Exercise: “If you don’t use them, you lose them.” Weight-bearing exercise is one of the best things you can do to increase your bone strength because of the concentrated pressure it puts on your bones.
- Diet: A diet lacking in calcium plays a major role in the development of osteoporosis. Eating calcium-rich foods and supplementing with a quality calcium supplement will ensure you are getting the adequate amounts needed.
- Family history: Having a family member with osteoporosis puts you at greater risk as osteoporosis is genetic.
- Body size: Women and men who have small body frames tend to have a higher risk for osteoporosis.
How A Bone Density Scan Works
A DEXA scan involves lying down, generally fully clothed, on a scanning table, and a scanning arm painlessly and non-invasively scans over your spine, and then over your hips, to help determine the quantity of bone that you have. The results are calculated in a computer, and you’re told your T-score; that’s the result of the bone density test. You’re given what’s T-score.
If your score is between 0 and -1, you are considered normal. If it’s between -1 and -2.49, it’s called low bone mass, sometimes referred to as osteopenia, but we prefer low bone mass. If it’s below -2.5, that’s called osteoporosis. You can only use those terms if you’re woman and you’re post-menopausal. If you’re pre-menopausal, you might get one of those labels given to you, but it doesn’t have the same meaning as it does when you’re post-menopausal.
AlgaeCal encourages all current and future customers to measure their bone density with a DEXA scan, and will guarantee an increase in bone mineral density through the use of AlgaeCal Plus and Strontium Boost in as little as 180 days.
Should I Be Concerned About Radiation Exposure?
Thankfully, as you can see from the chart below, there is very little exposure when compared to numerous other types of medical imaging procedures.
|Procedure||Average Effective Dose (mSv)||Range Reported in the Literature (mSv)|
|Bone density DEXA||0.001||0.00 – 0.035|
|X-ray, arm or leg||0.001||0.0002 – 0.1|
|X-ray, panoramic dental||0.01||0.007 – 0.09|
|X-ray, chest||0.1||0.05 – 0.24|
|X-ray, abdominal||0.7||0.04 – 1.1|
|Mammogram||0.4||0.10 – 0.6|
|X-ray, lumbar spine||1.5||0.5 – 1.8|
|CT, head||2||0.9 – 4|
|CT, cardiac for calcium scoring||3||1.0 – 12|
|Nuclear imaging, bone scan||6.3||?|
|CT, spine||6||1.5 – 10|
|CT, pelvis||6||3.3 – 10|
|CT, chest||7||4.0 – 18|
|CT, abdomen||8||3.5 – 25|
|CT, colonoscopy||10||4.0 – 13.2|
|CT, angiogram||16||5.0 – 32|
|CT, whole body||variable||20 or more|
For perspective, the amount of radiation emitted that’s listed on the chart above for a DEXA (0.001) is less than what you would get from a New York to L.A. flight.
If you go back a few decades, the only place to measure the health of your bones was at a hospital using a Central full body DEXA machine . But to meet the demand for the ever increasing cases of osteoporosis, more affordable, portable machines to test bone density were invented.
Due to the wonders of technology, with DEXA machines we can now safely, quickly and painlessly spot a bone density issue far on the distant horizon – and then do something about it – before a bone fracture alerts you to the problem.
Considering Bone Density Treatments
How to Read Your DEXA Scan Results.
That’s ok. And totally normal.
Which is why we’re going to discuss your T and Z-scores (the main numbers shown after your DEXA scan) and break them down so they’re easily understandable.
Here’s the basic understanding:
- Above -1 = Your bone density is considered normal
- Between -1 and -2.5 = Your score is a sign of osteopenia, a condition in which bone density is below normal and may lead to osteoporosis
- Below -2.5 = Your bone density indicates you have osteoporosis
But let’s dig in a little more…
What’s My Z-Score and Why Is It Useful?
In technical speak, the Z-score is a measure of the number of standard deviations away that your bone mineral density is from the average person of your age and gender.
An easy way to think about it is that your Z-score helps you see how you’re doing compared to other people in your age range.
As you know, one in two women over age 50 will break a bone because of osteoporosis. So if you’re over 50, the Z-score is a good way to understand how your bone health measures up to people your own age. But when it comes to your overall bone health there is a better indication of how you’re doing. Enter the T-Score.
What is a T-Score and What Does it Tell Me?
The T-score is a measure of the number of standard deviations your bone density is away from a “Young Adult’s” bone density. It gives you an idea of how you compare to someone considered to be at peak bone health.
Once you reach your peak bone mass around age 40, you begin to lose 1% of your bone mineral density each year on average. That is why comparing your bone density to a young adult’s is more practical because they are at a lower risk for fractures.
The pictures below will give you a visual representation of your scores.
For both rows pictured below, the number on the top of each figure is the T-score for the Bone Mineral Density (BMD) that will be reported for any bone density test you’ve taken (Left Femur, Right Femur, Spine, or Total Body).
At the bottom of each figure is a “%” score associated with the T-score value. Using a scale of 1 to 100, the “%” score is how your BMD compares to people of your gender in the standard comparison group of “Young Adults” that is used to diagnose osteopenia and osteoporosis.
For example, if your T-score was 0.6, your “%” score would be “73%” suggesting that your BMD was better than 73 out of 100 people of your gender in the comparison group and worse than only 26 out of 100.
- The green figures above indicate above average BMD, the darker the green, the better your BMD.
- The yellow figures indicate that you are in low bone density territory.
- The orange figures indicate Osteopenia (-1.0 to -2.4) , where bone density is below normal and may lead to osteoporosis.
- The red figures indicate Osteoporosis (-2.5 and below) which is severe bone loss. Making significant changes to your lifestyle is crucial if you are to increase your bone density.
What’s the Best Way to Measure my Progress?
You may have been told by your Doctor that your BMD has increased by X percent. While this is a good indicator of how much you improved, you can also use the “%” score associated with your T-score, which is at the bottom of each figure mentioned above.
For example, let’s say your T-scores increased from 0.6 to 0.8. Instead of saying it improved by 33.3%, just look up the “%” score for 0.6, (“73%”) and 0.8 (“79%”).
As you can see, your BMD went from better than 73% of “Young Adults” to better than 79% of “Young Adults” – a more accurate measure of change.
Care and Treatment for Osteoporosis
Understanding osteoporosis treatment is vital for you, your family and friends and your caregivers. Osteoporosis treatment includes a multifaceted regimen of diet, lifestyle habits, and osteoporosis supplements to help prevent (and hopefully reverse) further bone loss and fractures.
If your DEXA test reveals you have osteoporosis, the following are care and treatment options:
- Fracture Healing: Understand bone fracture healing, the process and more to prevent and treat current fractures.
- Medications: Osteoporosis treatments come in several forms and often include prescription drugs. You must be careful of some of these prescription drugs, as they have shown to have some serious, negative side-effects.
- Exercise: Exercise is a crucial aspect for care and treatment of osteoporosis. You should focus on two types of exercise for optimal results.
- Lifestyle Changes: Treatments can include improved diet, exercise and increased supplementation with a combination of calcium, vitamin d3 and k2, magnesium, boron and other trace elements your bones need.
- Bone Building Minerals: If you are concerned about the bone-thinning disease osteoporosis, one treatment you may have heard of and considered is a combination of calcium and strontium.
For the most effective treatment – actual increases in bone density – take the plant-based calcium source AlgaeCal Plus. It contains not only natural calcium – from a plant, not a rock – it also includes all the vitamins and minerals your bones need to promote bone density health.
Clinical studies prove that it stops bone density loss – but can increase bone density!
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Common Questions About Bone Density Testing
The only truly accurate way to check your bone density is with a DEXA scan. Regular x-rays will not give you the details (T-score and Z-score) your doctor needs to make an accurate diagnosis.
What is the actual name of the bone density test?
DEXA stands for Dual Energy X-Ray Absorptiometry. There are two types: Central and Peripheral. The first covers your entire skeleton; the later focuses on your extremities, such as your hands or feet.
How much does it cost for a bone density test?
In the US, Medicare covers the cost of your DEXA scan every two years. If you need more scans, please check with your insurance provider for complete coverage details.
In Canada, the Federal Government says that if you’re 65 and never had a DEXA, Canadian Medicare will cover it. They’ll also let you do follow-up DEXAs if you need them, every 2 years and cover them. Sometimes, if your treatments are annual, Medicare will cover the cost.
What if you’re less than 65? Most commercial providers will cover your initial DEXA if you’re post-menopausal and you have risk factors (such as smoking, genetics, under or overweight.)
If your health insurance does not cover the cost of your DEXA scan, you will pay 132 US$ for your DEXA scan (based on BlueHealthBook.com.)
Where can I get a Bone Density Test?
Vancouver, British Columbia, Canada
Mobile DEXA scans and body composition imaging in the Vancouver British Columbia area
Vancouver DEXA Scan
More coming soon, if you would like to see your DEXA scan clinic listed here please contact us.
How often should I have a bone density test?
Once you reach one of the milestones listed below, you should have a DEXA every 2 years:
- You are a woman 65 or better
- You are a postmenopausal woman under 65
- You are a man 70 or better
- You are 50 or better and recently suffered a bone fracture, especially from a minor fall
You should also consider an exam every year. The reason for a yearly exam is to confirm your treatment plan is working most efficiently and producing the healthier bones you want.
- National Osteoporosis Foundation (NOF) : http://www.nof.org/
- Mettler FA, et al. “Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog“, Radiology (July 2008), Vol. 248, pp. 254–63.