Bone Density Testing
Why would I want to have a bone density test done?
Osteoporosis is often called a “silent disease” because people do not know they have it until they break a bone. It is important to find out about the strength of your bone so that you can make adjustments that will help you prevent fractures before they ever occur.
Simple X-rays do not allow us to evaluate bone strength. Only after considerable bone is lost will X-rays start to show changes.
Tools for accurately measuring bone mass have been developed and these can be used to evaluate individuals at risk for osteoporosis. The results can be used to estimate risk of fracture, to identify those individuals who need a program of medical treatment, and to follow an individual's response to a program of care.
Several types of tests are available and all are painless and quick to perform without any special preparation. All forms of bone density testing are accurate and useful, but different tests will answer different questions for you and your doctor.
Which areas of my body will be scanned?
Currently the best and most commonly used test is called DXA [dual energy X-ray absorptiometry] which focuses on the central skeleton and measures bone mass at the hip and the lumbar spine. This technique can also be used to measure bone mass in the forearm if prior surgery or arthritis appear to be interfering with the accuracy of measurements at other sites.
Is there radiation involved?
Unlike a standard X-ray, this technique uses only very low levels of radiation.
How long does this procedure take?
You will be scheduled for a 30-minute appointment at the Osteoporosis Center but your scan itself will only take a few minutes. The additional time is spent gathering information that will help us guide your doctor in interpreting the results and making decisions about your management.
Are there any other tools available that can be used to evaluate bone health?
Another tool has been developed that makes use of ultrasound or sound waves. This device has been standardized so that the heel can be evaluated and a measurement of bone mass derived. This test is typically used in individuals who do not have identified risk factors for osteoporosis to get a general sense of their bone health. If an individual is identified to have a reduction in their bone mass by ultrasound, then they are usually encouraged undergo additional evaluation by DXA of the hip and spine to better define their risk for fracture and determine their need for treatment.
Will my insurance cover the cost of bone density testing?
Almost all insurance companies, including Medicare, will cover bone density testing by DXA in the following situations:
- all women over the age of 65
- postmenopausal women who are trying to make decisions about the management of their bone health
- individuals who have fractured with minimal trauma [ with no more force than you would generate with a fall from the standing position]
- individuals taking steroids or other medications that can cause accelerated bone loss
- individuals with diseases that can adversely affect bone health like hyperparathyroidism
- individuals receiving treatment to evaluate their response
This test is not just for women. Men meet some of the above criteria too and should be encouraged to undergo bone density testing as well.
The International Society for Clinical Densitometry has recommended that all men beyond the age of 70 undergo bone density testing, but Medicare and other insurance companies have not accepted that recommendation to date
If you think you might need a bone density study, you should discuss this with your physician.
How will I know what the results of my bone density study mean?
The results of your scan will be forwarded to your doctor with a formal interpretation of the results and some general suggestions about management. We think you and your doctor should be the ones to review this information and then make decisions about your care.
You might benefit from understanding that DXA scans do provide several kinds of information about your bone health:
BMD- bone mineral density
– an actual measurement of your bone mass
– a scoring system that allows us to compare your bone strength to that of a perfectly healthy 30-year old whom we assume is not at any increased risk of fracture. This comparison allows us to estimate your risk of fracture.
- For example:
If your T score is “0” your bone mass is identical to that of a healthy 30-yr old
If your T score is preceded by “+” your bone mass is better than a healthy 30-yr old
If your T score preceded by “-“ your bone mass falls below that of a healthy 30-yr old
- The World Health Organization developed some general guidelines for categorizing bone health in large populations by T scores:
Normal – T scores of greater than –1.0
Low Bone Mass also called “osteopenia” - T scores between –1.0 to –2.5
Osteoporosis – T scores of –2.5 or below
These cutoffs are not intended as guidelines for treatment
Physicians usually want to initiate treatment before serious reduction in bone strength has developed
How often should a bone density study be repeated?
How much change should I expect on a follow-up scan to know my program of care is working?
- It depends on what you are using the follow-up scan to evaluate.
- If measuring response to treatment, then a DXA scan is usually repeated every 2 years.
- If monitoring for steroid-induced bone loss, then it might be important to repeat in 6-12 months.
- We are satisfied if patients remain stable on follow-up scans.
- You do not have to gain bone to have improvement in your fracture risk.
- The most important role of follow-up bone density testing is to identify patients who are continuing to lose bone.