First, your BMD result is compared with the BMD results from healthy to year-old adults of your same sex and ethnicity. This result is your T-score. Positive T-scores indicate the bone is stronger than normal; negative T-scores indicate the bone is weaker than normal. According to the World Health Organization, osteoporosis is defined based on the following bone density levels:.
A T-score of 2. In general, the risk for bone fracture doubles with every SD below normal. When this information is known, people with a high risk for bone fracture can be treated with the goal of preventing future fractures.
Severe established osteoporosis is defined as having a bone density that is more than 2. Secondly, your BMD is compared to an age-matched norm.
This is called your Z-score. Z-scores are calculated in the same way, but the comparisons are made to someone of your age, sex, race, height, and weight. A bone density test is mainly done to look for osteoporosis thin, weak bones and osteopenia decreased bone mass so that these problems can be treated as soon as possible. Early treatment helps to prevent bone fractures. The complications of broken bones related to osteoporosis are often severe, particularly in the elderly.
There are many risk factors for osteoporosis and indications for densitometry testing. Some common risk factors for osteoporosis include:. Certain diseases, including rheumatoid arthritis, type 1 diabetes mellitus, liver disease, kidney disease, hyperthyroidism, or hyperparathyroidism. Health Home Treatments, Tests and Therapies.
Routine evaluations every two years may be needed to see a significant change in bone mineral density, decrease or increase. Few patients, such as patients on high dose steroid medication, may need follow-up at six months.
A radiologist , a doctor trained to supervise and interpret radiology examinations, will analyze the images. The radiologist will send a signed report to your primary care or referring physician who will discuss the results with you.
DXA scans are also interpreted by other physicians such as rheumatologists and endocrinologists. A clinician should review your DXA scan while assessing the presence of clinical risk factors such as:. T score — This number shows the amount of bone you have compared with a young adult of the same gender with peak bone mass. A score of -1 and above is considered normal. A score between A score of The T score is used to estimate your risk of developing a fracture and also to determine if treatment is required.
Z score — This number reflects the amount of bone you have compared with other people in your age group and of the same size and gender. If this score is unusually high or low, it may indicate a need for further medical tests. Small changes may normally be observed between scans due to differences in positioning and usually are not significant. Doctors take special care during x-ray exams to use the lowest radiation dose possible while producing the best images for evaluation.
National and international radiology protection organizations continually review and update the technique standards radiology professionals use. Modern x-ray systems minimize stray scatter radiation by using controlled x-ray beams and dose control methods.
This ensures that the areas of your body not being imaged receive minimal radiation exposure. Please type your comment or suggestion into the text box below. Note: we are unable to answer specific questions or offer individual medical advice or opinions.
Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database. This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region.
Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America RSNA and the American College of Radiology ACR , comprising physicians with expertise in several radiologic areas. Outside links: For the convenience of our users, RadiologyInfo.
Toggle navigation. What are some common uses of the procedure? How should I prepare? What does the equipment look like? How does the procedure work? How is the procedure performed? What will I experience during and after the procedure? Who interprets the results and how will I get them? What are the benefits vs. Bone density testing is strongly recommended if you: are a post-menopausal woman and not taking estrogen.
The Vertebral Fracture Assessment VFA , a low-dose x-ray examination of the spine to screen for vertebral fractures that is performed on the DXA machine, may be recommended for older patients, especially if: they have lost more than an inch of height.
There are two types of DXA equipment: a central device and a peripheral device. Your doctor will likely do this exam on an outpatient basis. Bone density tests are a quick and painless procedure. A clinician should review your DXA scan while assessing the presence of clinical risk factors such as: rheumatoid arthritis chronic renal and liver disease respiratory disease inflammatory bowel disease Your test results will be in the form of two scores: T score — This number shows the amount of bone you have compared with a young adult of the same gender with peak bone mass.
Benefits DXA bone densitometry is a simple, quick and noninvasive procedure. No anesthesia is required. The amount of radiation used is extremely small—less than one-tenth the dose of a standard chest x-ray, and less than a day's exposure to natural radiation. DXA bone density testing is currently the best standardized method available to diagnose osteoporosis and is also considered an accurate estimator of fracture risk. DXA is used to make a decision whether treatment is required and it can be used to monitor the effects of the treatment.
DXA equipment is widely available making DXA bone densitometry testing convenient for patients and physicians alike. No radiation stays in your body after an x-ray exam. X-rays usually have no side effects in the typical diagnostic range for this exam. Risks There is always a slight chance of cancer from excessive exposure to radiation.
However, given the small amount of radiation used in medical imaging, the benefit of an accurate diagnosis far outweighs the associated risk. Women should always tell their doctor and x-ray technologist if they are pregnant. The radiation dose for this procedure varies. No complications are expected with the DXA procedure. A Word About Minimizing Radiation Exposure Doctors take special care during x-ray exams to use the lowest radiation dose possible while producing the best images for evaluation.
A DXA test cannot predict who will experience a fracture but can provide a relative risk and it is used to determine whether treatment is required. Despite its effectiveness as a method of measuring bone density, DXA is of limited use in people with a spinal deformity or those who have had previous spinal surgery.
The presence of vertebral compression fractures or osteoarthritis may interfere with the accuracy of the test; in such instances, CT scans may be more useful. Central DXA devices are more sensitive and better standardized than pDXA devices but they are also somewhat more expensive.
A test done on a peripheral location, such as the heel or wrist, may help predict the risk of fracture in the spine or hip. These tests are not as helpful in following response to treatment, however, and if they indicate that drug therapy is needed, a baseline central DXA scan should be obtained. Follow-up DXA exams should be performed at the same institution and ideally with the same machine.
Bone density measurements obtained with different DXA equipment cannot be directly compared. Send us your feedback Did you find the information you were looking for? Yes No.
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