Bone Densitometry
Bone densitometry is used to assess bone density and to screen for persons with increased risk of osteoporosis. Generally speaking, the density of several key bones is measured. This procedure takes about 20 minutes and is painless. It is important, however, to remain still for the duration of the test.
Patients are asked to lie on their backs with their legs propped up on a cushion. Then, a scanner slowly passes over the areas to be examined. The device transmits a small quantity of X-rays through the body. A person's bone density is calculated using data collected by the computer.
Preparation
- It is recommended that you do not take any calcium supplements 24 hours prior to the test.
- Wear loose fitting, comfortable clothes that do not have metal zipper, belt or buttons.
What is the purpose of this test?
Bone densitometry is a surefire way to identify those at risk of developing osteoporosis. Osteoporosis has no symptoms. Countless people therefore do not know that they have it until they fracture a bone.
This type of test is used to detect bone mass loss. It is also helpful at estimating fracture risk and, if repeated, determining the rate at which bone loss is occurring. It can also be used to monitor and assess response of any osteoporosis treatment.
Bone density tests are recommended for people with a history of fractures, who have certain risk factors or who are aged 70 or over.
Risk factors include, among others:
- Use of glucocorticoids
- Have had more than 2 falls in the past year
- Parent fractured hip
- Body mass index < 20="">2
- Current smoking
- Alcohol ≥ 3 drinks/day
- Certain diseases that increase the risk of osteoporosis, such as:
- Endocrine disorders (e.g., hyperthyroidism, diabetes)
- Gastrointestinal or nutritional disorders (e.g., inflammatory bowel disease, vitamin D or calcium deficiency)
- Certain autoimmune diseases (e.g., systemic lupus erythematous, rheumatoid arthritis)
What does an abnormal result mean?
Results are analyzed by a radiologist. They are generally given as a T score. This result compares bone density at the time of the test to that of a young adult of the same gender with a maximum bone density.
| T score | Description |
|---|---|
| Between -1 and +2.5 | Normal result |
| Between -2.5 and -1 | Osteopenia (first stage of bone loss) |
| Less than -2.5 | Osteoporosis |
The result can also be given as a Z score which corresponds to the difference between the measured value and the theoretical value adjusted for age and gender.
What you should know before going for this test
When you go in for a blood test or any other medical exam, it's always a good idea to bring a complete list of any prescriptions, over-the-counter medications, or natural health products you're taking. Unless otherwise advised, it's best to take your medications as usual on blood test days. If in doubt, don't hesitate to talk to your healthcare professional.
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.