Most types of QCT tests provide the same type of T-scores for bone mineral density at the hip as does DXA, but at the spine can provide a measurement of bone mineral density of just the spongy bone inside your vertebra.

This type of spinal measurement may be preferred if your spinal bones have degenerative disease. QCT is not as widely used as DXA due to limited availability, higher radiation dose, and being less practical to monitor treatment for most patients.

BCT is an advanced technology that uses data from a CT scan to measure bone mineral density. BCT also uses engineering analysis finite element analysis or FEA to estimate bone strength or measure the breaking strength of bone.

REMS is a portable method that does not use radiation that gives bone density measurements of the hip and spine. These types of tests measure bone density or other parameters in the peripheral skeleton, namely the arm, leg, wrist, fingers, or heel. Examples include:.

The results from these types of tests are not comparable to central DXA measurement and therefore difficult to interpret for diagnostic purposes and thus additional testing is often required. Screening tests cannot accurately diagnose osteoporosis and should not be used to see how well an osteoporosis medicine is working.

Most people need a prescription or referral from their healthcare provider to have a bone density test. The ideal facility is one with staff that are trained and certified by an organization such as the ISCD, and better yet, one that has been accredited by the ISCD.

Most hospital radiology departments, private radiology groups, and some medical practices offer bone density testing. When you go for your appointment, be sure to take the prescription or referral with you.

The testing center will send your bone density test results to your healthcare provider. You may want to make an appointment to discuss your results with your healthcare provider.

As with any medical test, bone density should be repeated when the results might influence treatment plans.

It is often repeated years after starting or changing osteoporosis medication to evaluate response to treatment.

It might also be repeated in years if you are not being treated but are close to a treatment threshold. Subsequent testing varies according to your individual situation. For postmenopausal women and men age 50 years and older, the T-score is the number that is used for diagnostic classification, as follows:.

It is important to recognize that you may be diagnosed with osteoporosis when the T-score is better than Your results may also include a TBS — trabecular bone score.

This reflects the microarchitecture of bone in the spine. Results are classified as normal, partially-degraded, and degraded. Osteoarthritis in the spine and hip may increase measured bone mineral density.

If degenerative disease is present, your healthcare provider will focus on unaffected regions of interest. The trabecular bone score is not impacted by osteoarthritis. Unlike various cancer screening modalities, there is no upper age limit for bone density screening.

DEXA Bone Density Tests: A Patient's Guide. By ; Alana C. Serota, MD, CCFP, CCD. What is a bone density test? Who should have a DEXA bone density test? What happens during a DEXA scan? What do my DEXA scan results mean? Does arthritis show up on a bone density test? At what age should you stop getting tested?

When the hip and spine cannot be measured, the diagnosis of osteoporosis can be made using a DXA measurement of the forearm. If you have a condition known as hyperparathyroidism, the forearm may also be measured in addition to the spine and hip because the bone density at the forearm may be lower than at the hip with these conditions.

If you have a DXA study done, make sure that your doctor gets the DXA images as well as the actual bone density values. These measurements can hold important clues that are not always on the summary statements. If your doctor recommends a follow-up DXA usually two years or more between studies , try to have the follow-up study done at the same facility as the first one.

There are different models of DXA instruments, and the bone density measurements are easier to compare if they have been taken on the same model. Quantitative computerized tomography — This is a type of computed tomography CT that provides accurate measures of bone density in the spine.

Although this test may be an alternative to DXA, it is seldom used because it is expensive and requires a higher radiation dose. Ultrasound — Ultrasound can be used to measure the bone density of the heel.

This may be useful to determine a person's fracture risk. However, it is used less frequently than DXA because there are no guidelines that use ultrasound measurements to diagnose osteoporosis or predict fracture risk.

In areas that do not have access to DXA, ultrasound is an acceptable way to measure bone density. WHAT TO EXPECT FROM A DXA TEST. During dual-energy x-ray absorptiometry DXA , you lie on an examination table. An x-ray detector scans a bone region, and the amount of x-rays that pass through bone are measured and displayed as an image that is interpreted by a radiologist or metabolic bone expert.

The test causes no discomfort, involves no injections or special preparation, and usually takes only 5 to 10 minutes. The x-ray detector will detect any metal on your clothing zippers, belt buckles , so you may be asked to wear a gown for the test.

It is also recommended that you avoid taking calcium supplements in the 24 hours before your test, as these supplements can sometimes interfere with the images. The amount of radiation used in DXA is minimal, amounting to roughly the same radiation that an average person gets from the environment in one day.

After the test is completed and the doctor interprets the results, you will be given a score that speaks to the condition of your bones.

WHAT DO THE RESULTS MEAN? The results of a bone density test are expressed either as a "T" or a "Z" score. T-scores represent numbers that compare the condition of your bones with those of an average young person with healthy bones.

Z-scores instead represent numbers that compare the condition of your bones with those of an average person your age. Of these two numbers, the T-score is usually the most important. T-scores are usually in the negative or minus range. The lower the bone density T-score, the greater the risk of fracture table 1.

People who have a score in this range do not typically need treatment, but it is useful for them to take steps to prevent bone loss, such as having adequate amounts of calcium and vitamin D and doing weightbearing exercise.

Low bone mass osteopenia — Low bone mass osteopenia is the term health care providers use to describe bone density that is lower than normal but that has not yet reached the low levels seen with osteoporosis. A person with osteopenia does not yet have osteoporosis but is at risk of developing it.

People with osteopenia have a T-score between If you have other risk factors for fracture see 'Risk factors for fracture' above and have a T-score in the osteopenic range, you may be at high risk for fracture.

People with low bone mass are usually advised to take steps to prevent osteoporosis. Sometimes that includes taking medications. Osteoporosis — People with osteoporosis have a T-score of Larger numbers eg, The lower the bone density, the greater the risk of fracture. If you discover that you have osteoporosis, there are several things you can do to reduce the chances that you will break a bone.

For instance, you can take osteoporosis medications combined with calcium and vitamin D supplements, and you can do an exercise program. See "Patient education: Calcium and vitamin D for bone health Beyond the Basics " and "Patient education: Osteoporosis prevention and treatment Beyond the Basics ".

Note that if you have previously had a low trauma bone fracture, you are also classified as having osteoporosis and need to take osteoporosis medications, regardless of your bone density T-score. Fracture prediction tool — Fracture Risk Assessment Tool FRAX is an online tool that was developed to estimate your year likelihood of having a minimal trauma fracture.

You can use it to determine your fracture risk even if you have not had a dual-energy x-ray absorptiometry DXA test, but you will get a more accurate prediction if you include DXA results.

If you decide to use the FRAX tool on your own, without a DXA study, and the results indicate a high risk of fracture, then it may be helpful to ask your health care provider whether you can also have a DXA test.

This DXA will serve as a baseline by which your doctor can follow your response to treatment. If the FRAX tool indicates that you have a high risk of fracture, your doctor may also recommend that you start on antifracture medications, regardless of your bone density results. FRAX should not be used if you have already had a minimal trauma fracture or are already on treatment aimed at preserving your bone health and preventing future fractures.

DO I NEED TO HAVE BONE DENSITY TESTING AGAIN? Even if your bone density test shows that you do not have osteoporosis today, you may need to have the test again. How long to wait between tests depends on your initial bone density results and whether you have risk factors that represent an ongoing threat to your bones.

Quantitative computerized tomography — This is a type of computed tomography CT that provides accurate measures of bone density in the spine. Although this test may be an alternative to DXA, it is seldom used because it is expensive and requires a higher radiation dose.

Ultrasound — Ultrasound can be used to measure the bone density of the heel. This may be useful to determine a person's fracture risk. However, it is used less frequently than DXA because there are no guidelines that use ultrasound measurements to diagnose osteoporosis or predict fracture risk.

In areas that do not have access to DXA, ultrasound is an acceptable way to measure bone density. WHAT TO EXPECT FROM A DXA TEST. During dual-energy x-ray absorptiometry DXA , you lie on an examination table.

An x-ray detector scans a bone region, and the amount of x-rays that pass through bone are measured and displayed as an image that is interpreted by a radiologist or metabolic bone expert.

The test causes no discomfort, involves no injections or special preparation, and usually takes only 5 to 10 minutes. The x-ray detector will detect any metal on your clothing zippers, belt buckles , so you may be asked to wear a gown for the test. It is also recommended that you avoid taking calcium supplements in the 24 hours before your test, as these supplements can sometimes interfere with the images.

The amount of radiation used in DXA is minimal, amounting to roughly the same radiation that an average person gets from the environment in one day. After the test is completed and the doctor interprets the results, you will be given a score that speaks to the condition of your bones.

WHAT DO THE RESULTS MEAN? The results of a bone density test are expressed either as a "T" or a "Z" score.

T-scores represent numbers that compare the condition of your bones with those of an average young person with healthy bones. Z-scores instead represent numbers that compare the condition of your bones with those of an average person your age.

Of these two numbers, the T-score is usually the most important. T-scores are usually in the negative or minus range. The lower the bone density T-score, the greater the risk of fracture table 1.

People who have a score in this range do not typically need treatment, but it is useful for them to take steps to prevent bone loss, such as having adequate amounts of calcium and vitamin D and doing weightbearing exercise.

Low bone mass osteopenia — Low bone mass osteopenia is the term health care providers use to describe bone density that is lower than normal but that has not yet reached the low levels seen with osteoporosis.

A person with osteopenia does not yet have osteoporosis but is at risk of developing it. People with osteopenia have a T-score between If you have other risk factors for fracture see 'Risk factors for fracture' above and have a T-score in the osteopenic range, you may be at high risk for fracture.

People with low bone mass are usually advised to take steps to prevent osteoporosis. Sometimes that includes taking medications. Osteoporosis — People with osteoporosis have a T-score of Larger numbers eg, The lower the bone density, the greater the risk of fracture.

If you discover that you have osteoporosis, there are several things you can do to reduce the chances that you will break a bone. For instance, you can take osteoporosis medications combined with calcium and vitamin D supplements, and you can do an exercise program.

See "Patient education: Calcium and vitamin D for bone health Beyond the Basics " and "Patient education: Osteoporosis prevention and treatment Beyond the Basics ". Note that if you have previously had a low trauma bone fracture, you are also classified as having osteoporosis and need to take osteoporosis medications, regardless of your bone density T-score.

Fracture prediction tool — Fracture Risk Assessment Tool FRAX is an online tool that was developed to estimate your year likelihood of having a minimal trauma fracture.

You can use it to determine your fracture risk even if you have not had a dual-energy x-ray absorptiometry DXA test, but you will get a more accurate prediction if you include DXA results.

If you decide to use the FRAX tool on your own, without a DXA study, and the results indicate a high risk of fracture, then it may be helpful to ask your health care provider whether you can also have a DXA test.

This DXA will serve as a baseline by which your doctor can follow your response to treatment. If the FRAX tool indicates that you have a high risk of fracture, your doctor may also recommend that you start on antifracture medications, regardless of your bone density results.

FRAX should not be used if you have already had a minimal trauma fracture or are already on treatment aimed at preserving your bone health and preventing future fractures. DO I NEED TO HAVE BONE DENSITY TESTING AGAIN? Even if your bone density test shows that you do not have osteoporosis today, you may need to have the test again.

How long to wait between tests depends on your initial bone density results and whether you have risk factors that represent an ongoing threat to your bones.

Repeat bone density measurements may be most valuable for people who are taking a medication to treat osteoporosis to determine the efficacy of treatment and for people who are not being treated but have medical conditions that can cause bone loss to determine if they need treatment.

Bone density tests help health care providers spot bone loss in people who might otherwise have no symptoms. The tests are painless, quick, and safe, and they can alert people to bone loss before they have a fracture. The tests are also useful in tracking the effects of medications used to manage bone disease.

Your health care provider is the best source of information for questions and concerns related to your medical problem. This article will be updated as needed on our website www. Related topics for patients, as well as selected articles written for health care professionals, are also available.

Some of the most relevant are listed below. Patient level information — UpToDate offers two types of patient education materials. The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition.

These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Patient education: Bone density testing The Basics Patient education: Osteoporosis The Basics Patient education: Calcium and vitamin D for bone health The Basics Patient education: Vitamin D deficiency The Basics Patient education: Primary hyperparathyroidism The Basics Patient education: Hip fracture The Basics Patient education: Vertebral compression fracture The Basics Patient education: Cadmium toxicity The Basics Patient education: Medicines for osteoporosis The Basics.

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon. Patient education: Osteoporosis prevention and treatment Beyond the Basics Patient education: Calcium and vitamin D for bone health Beyond the Basics.

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings.

These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Clinical manifestations, diagnosis, and evaluation of osteoporosis in postmenopausal women Osteoporotic fracture risk assessment Screening for osteoporosis in postmenopausal women and men. htm , available in Spanish. org , available in English and Spanish. Why UpToDate? Product Editorial Subscription Options Subscribe Sign in.

Learn how UpToDate can help you. Select the option that best describes you. View Topic. Font Size Small Normal Large. Patient education: Bone density testing Beyond the Basics. Formulary drug information for this topic. No drug references linked in this topic. Find in topic Formulary Print Share.

Osteoporosis increases the risk for broken bones and can have serious effects in older adults. What To Expect Before the procedure Make sure to let your healthcare provider or radiologist medical professional specially trained in radiation procedures if you are pregnant or think you may or could be pregnant.

Dress in loose, comfortable clothing. Metal can interfere with test results. During the procedure You may be asked to remove jewelry, eyeglasses, and any clothing that may interfere with the imaging.

You will lay on a table and the radiologist or medical assistant will position your legs on a padded box. They also may place your foot in a device so that your hip is turned inward. While the image is taken, lay still and follow instructions. You may need to hold your breath for a few seconds.

After the procedure The procedure typically lasts about minutes. Your healthcare provider will follow up with you with your results. They will show a T-score and a Z-score. The T-score shows how your bone density compares to the optimal peak bone density for your gender. The Z-score shows how your bone density compares to the bone densities of others who are the same age, gender, and ethnicity.

Related Links. FDA Reducing Radiation from Medical X-rays external icon Pediatric X-ray Imaging external icon Radiology and Children: Extra Care Required external icon X-Rays, Pregnancy and You external icon Medical X-rays: How Much Radiation are You Getting external icon Image Gently What Parents should Know about Medical Radiation Safety pdf icon [PDF — kb] external icon Educational Materials external icon EPA RadTown USA Medical X-Rays external icon Radiation Protection Guidance for Diagnostic and Interventional X-Ray Procedures external icon US National Library of Medicine Diagnostic Imaging external icon.

Page last reviewed: October 20, Content source: Centers for Disease Control and Prevention. home Radiation Home. Related Pages. Contact Us Calendar Employment. Links with this icon indicate that you are leaving the CDC website.

The Centers for Disease Control and Prevention CDC cannot attest to the accuracy of a non-federal website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.

DEXA dual x-ray absorptiometry scans measure bone density thickness and strength of bones by passing a high and low energy x-ray beam a form of ionizing radiation through the body, usually in the hip and the spine. This procedure is important for diagnosing seeing if someone has osteoporosis or bone thinning and may be repeated over time to track changes in bone density.

The amount of radiation used in DEXA scans is very low and similar to the amount of radiation used in common x-rays. Although we all are exposed to ionizing radiation every day from the natural environment, added exposures can slightly increase the risk of developing cancer later in life.

Your healthcare provider may recommend a DEXA scan to test for osteoporosis or thinning of your bones. Screening for osteoporosis is recommended for women who are 65 years old or older and for women who are 50 to 64 and have certain risk factors, such as having a parent who has broken a hip.

However, there are other risk factors for osteoporosis besides age and gender, such as some intestinal disorders, multiple sclerosis, or low body weight. Your healthcare provider may recommend a DEXA scan if you have any of these other risk factors.

DEXA scans should be used when the health benefits outweigh the risks. Talk to your healthcare provider about any concerns you have before a DEXA scan.

Find information on special considerations pregnant women and children. Learn more about the benefits and risks of imaging tests, including nuclear medicine, and how to reduce your exposure to radiation. DEXA scans are different from other imaging procedures because they are used to screen for a specific condition.

Skip directly to site content Skip directly to page options Skip directly to A-Z link. Radiation and Your Health. Section Navigation. Facebook Twitter LinkedIn Syndicate. Radiation in Healthcare: Bone Density DEXA Scan Minus Related Pages.

What You Should Know Your healthcare provider may recommend a DEXA scan to test for osteoporosis or thinning of your bones. Nearly 1 in 5 women and 1 in 20 men over the age of 50 are affected by osteoporosis. Osteoporosis increases the risk for broken bones and can have serious effects in older adults.

What To Expect Before the procedure Make sure to let your healthcare provider or radiologist medical professional specially trained in radiation procedures if you are pregnant or think you may or could be pregnant.

Dress in loose, comfortable clothing. Fractures of the spine and hip can lead to chronic pain, deformity, depression, disability, and even death. Plus, half the people who break a hip never regain the ability to walk without assistance, and a quarter need long term care. The problem is that osteoporosis does not cause any symptoms, so people do not usually know they have the condition until they break a bone unexpectedly.

That's where bone density tests come in. Bone density tests measure how strong the bones are. Health care providers use these tests to both screen for and diagnose osteoporosis.

The tests are important, because they can alert you to problems with your bones before you have a fracture. If it turns out that you have osteoporosis or are at risk for it known as low bone mass or osteopenia , you can take steps to prevent fractures.

See "Patient education: Osteoporosis prevention and treatment Beyond the Basics ". WHO SHOULD GET BONE DENSITY TESTING? Osteoporosis is much more common in females than in males, and it becomes more common after menopause and with advancing age.

As a result, health care providers recommend bone density testing for people who have been through menopause and are at least 65 years old. In addition, there are certain characteristics that put people at higher risk for fracture, so health care providers sometimes recommend testing in people younger than 65 years who have one or more risk factors.

Risk factors for fracture — Factors that increase a person's risk of fracture and may lead to earlier bone density testing include:. WHICH TEST IS BEST? Dual-energy x-ray absorptiometry — Experts agree that the most useful and reliable bone density test is a specialized kind of x-ray called dual-energy x-ray absorptiometry, or DXA.

DXA provides precise measurements of bone density at important bone sites such as the spine, hip, and forearm with minimal radiation.

Most experts recommend DXA of the hip and spine because measurements at these sites are the best at predicting who will have an osteoporotic fracture, at identifying who should be treated for osteoporosis, and at monitoring response to treatment.

If you are unable to lie on an examination table, it will not be possible to measure your spine and hip bone density. Instead, you can sit beside the DXA machine for a scan of your forearm.

When the hip and spine cannot be measured, the diagnosis of osteoporosis can be made using a DXA measurement of the forearm. If you have a condition known as hyperparathyroidism, the forearm may also be measured in addition to the spine and hip because the bone density at the forearm may be lower than at the hip with these conditions.

If you have a DXA study done, make sure that your doctor gets the DXA images as well as the actual bone density values. These measurements can hold important clues that are not always on the summary statements.

If your doctor recommends a follow-up DXA usually two years or more between studies , try to have the follow-up study done at the same facility as the first one. There are different models of DXA instruments, and the bone density measurements are easier to compare if they have been taken on the same model.

Quantitative computerized tomography — This is a type of computed tomography CT that provides accurate measures of bone density in the spine.

Although this test may be an alternative to DXA, it is seldom used because it is expensive and requires a higher radiation dose. Ultrasound — Ultrasound can be used to measure the bone density of the heel. This may be useful to determine a person's fracture risk. However, it is used less frequently than DXA because there are no guidelines that use ultrasound measurements to diagnose osteoporosis or predict fracture risk.

In areas that do not have access to DXA, ultrasound is an acceptable way to measure bone density. WHAT TO EXPECT FROM A DXA TEST. During dual-energy x-ray absorptiometry DXA , you lie on an examination table. An x-ray detector scans a bone region, and the amount of x-rays that pass through bone are measured and displayed as an image that is interpreted by a radiologist or metabolic bone expert.

The test causes no discomfort, involves no injections or special preparation, and usually takes only 5 to 10 minutes. The x-ray detector will detect any metal on your clothing zippers, belt buckles , so you may be asked to wear a gown for the test. It is also recommended that you avoid taking calcium supplements in the 24 hours before your test, as these supplements can sometimes interfere with the images.

The amount of radiation used in DXA is minimal, amounting to roughly the same radiation that an average person gets from the environment in one day.

After the test is completed and the doctor interprets the results, you will be given a score that speaks to the condition of your bones. WHAT DO THE RESULTS MEAN? The results of a bone density test are expressed either as a "T" or a "Z" score.

T-scores represent numbers that compare the condition of your bones with those of an average young person with healthy bones. Z-scores instead represent numbers that compare the condition of your bones with those of an average person your age. Of these two numbers, the T-score is usually the most important.

T-scores are usually in the negative or minus range. The lower the bone density T-score, the greater the risk of fracture table 1. People who have a score in this range do not typically need treatment, but it is useful for them to take steps to prevent bone loss, such as having adequate amounts of calcium and vitamin D and doing weightbearing exercise.

Low bone mass osteopenia — Low bone mass osteopenia is the term health care providers use to describe bone density that is lower than normal but that has not yet reached the low levels seen with osteoporosis.

A person with osteopenia does not yet have osteoporosis but is at risk of developing it. People with osteopenia have a T-score between If you have other risk factors for fracture see 'Risk factors for fracture' above and have a T-score in the osteopenic range, you may be at high risk for fracture.

People with low bone mass are usually advised to take steps to prevent osteoporosis. Sometimes that includes taking medications. Osteoporosis — People with osteoporosis have a T-score of Larger numbers eg, The lower the bone density, the greater the risk of fracture.

If you discover that you have osteoporosis, there are several things you can do to reduce the chances that you will break a bone. For instance, you can take osteoporosis medications combined with calcium and vitamin D supplements, and you can do an exercise program.

See "Patient education: Calcium and vitamin D for bone health Beyond the Basics " and "Patient education: Osteoporosis prevention and treatment Beyond the Basics ".

Note that if you have previously had a low trauma bone fracture, you are also classified as having osteoporosis and need to take osteoporosis medications, regardless of your bone density T-score.

Fracture prediction tool — Fracture Risk Assessment Tool FRAX is an online tool that was developed to estimate your year likelihood of having a minimal trauma fracture. You can use it to determine your fracture risk even if you have not had a dual-energy x-ray absorptiometry DXA test, but you will get a more accurate prediction if you include DXA results.

If you decide to use the FRAX tool on your own, without a DXA study, and the results indicate a high risk of fracture, then it may be helpful to ask your health care provider whether you can also have a DXA test.

This DXA will serve as a baseline by which your doctor can follow your response to treatment. If the FRAX tool indicates that you have a high risk of fracture, your doctor may also recommend that you start on antifracture medications, regardless of your bone density results.

FRAX should not be used if you have already had a minimal trauma fracture or are already on treatment aimed at preserving your bone health and preventing future fractures.

DO I NEED TO HAVE BONE DENSITY TESTING AGAIN? Even if your bone density test shows that you do not have osteoporosis today, you may need to have the test again.

How long to wait between tests depends on your initial bone density results and whether you have risk factors that represent an ongoing threat to your bones. Repeat bone density measurements may be most valuable for people who are taking a medication to treat osteoporosis to determine the efficacy of treatment and for people who are not being treated but have medical conditions that can cause bone loss to determine if they need treatment.

Bone density tests help health care providers spot bone loss in people who might otherwise have no symptoms. The tests are painless, quick, and safe, and they can alert people to bone loss before they have a fracture.

The tests are also useful in tracking the effects of medications used to manage bone disease. Your health care provider is the best source of information for questions and concerns related to your medical problem.