Bone Densitometry

General Information

Bone densitometry is used to assess bone density and to screen for person with increased risk of osteoporosis. Generally speaking, the density of several key bones is measured. This procedure takes between 20 and 30 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. Legs are elevated to flatten the pelvis and lower spine. 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. If the bone density of a hip must be measured, the foot is placed in a brace that is used to rotate the hip inwards.

What is the purpose of this test?

Bone densitometry is a sure fire 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. Fractures are often the result of a minor fall and commonly involve the femur (thigh bone), hip or distal radius (bone in the forearm).

This type of test is used to detect bone mass loss before a fracture occurs. It is also helpful at estimating fracture risk and, if repeated annually, determining the rate at which bone loss is occurring. It can also be used to monitor and assess response to future treatment.

Bone density tests are recommended for men and women 50 years of age and older who have at least one major risk factor or two minor risk factors. The following table lists these risk factors.

Major Risk Factors	Minor Risk Factors
Family history of hip fractures Being 65 years and older Propensity to falls Spontaneous bone fracture Menopause before age 45 Corticosteroid use for more than three months Hormone disorder (hypogonadism) Parathyroid gland disorders X-ray showing bone loss	History of thyroid gland disorder (hyperthyroidism) Alcohol abuse Heavy coffee drinker Low calcium intake (though food or supplements) Significant weight loss Weight inferior to 57 kg (125 pounds) Rheumatoid arthritis History of smoking Long-term heparin therapy Long-term anticonvulsant therapy (for epilepsy)

Preparation

• This test does not require any special diet on the day of the exam.
• It is recommended that you not take any calcium supplements 24 hours prior to the test.
• Wear loose fitting, comfortable clothes that do not have metal zippers, belts or buttons.
• You will be asked to answer a few questions before the test to identify osteoporosis risk factors.

What does an abnormal result mean?

Results are analysed by a radiologist. They are generally given as a T score:

Name	Description	Normal result	Abnormal result
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.	Between -1 and +2.5	Between -1 and -2.5: 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 to know before going for this test

Before going for a blood test, examination or other, it is always a good idea for you to have a complete list of all prescription or over the counter medications and/or natural products you may be taking. If you are unsure or have any questions, your pharmacist will be able provide you with additional information.