Bone Mineral Density

 

Bone Densitometry is a diagnostic tool for the detection of osteoporosis. The program promotes bone health and prevention or early detection of osteoporosis, and treatment.

Bone Mineral Density (BMD) studies are performed here at St. Francis Memorial Hospital and interpreted by the Radiologist.  The BMD program at St. Francis Memorial Hospital is accredited with the Canadian Association of Radiologists.

Appointments for BMD can be made by calling 756-3045 ext #252.

What is Bone Densitometry?

Bone Densitometry is a low radiation instrument designed to measure the Bone Mineral Content in the vertebral and femoral area. Bone Densitometry detects subtle bone changes and offers physicians information on the condition and fracture risk of the bones throughout the body.

Who Needs Testing?

Any men or women who are at risk of Osteoporosis.

Risks for Osteoporosis

  • Family history
  • Past history of fragility fractures
  • Menopausal women (especially premature [before age 45] menopause and surgical menopause)
  • Greater risk is the older postmenopausal women or longstanding menopause
  • Increasing age
  • Poor nutrition
  • Low calcium intake
  • Inactivity
  • Vitamin D deficiency
  • Tobacco use
  • Alcohol abuse
  • Hypogonadism in men
  • Weight below 57kgs (125lbs)
  • Steroid Therapy
  • Thyroid hormone replacement
  • Cancer chemotherapy
  • Anticovulsant
  • End stage renal disease
  • Primary hyperparathyroidism
  • Thyroid hypothroidism /hyperthyroidism

A bone mineral density (BMD) test measures how much calcium and other types of minerals are present in a section of your bone. Your health care provider uses this test, along with other risk factors, to predict your risk of bone fractures in the future and detect osteoporosis. Bone fracture risk is highest in people with osteoporosis.

Alternative Names

BMD test; Bone density test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA

How the Test is Performed

Several different kinds of machines can do BMD testing. The most common and most accurate method is called a dual-energy x-ray absorptiometry (DEXA) scan. It uses low-dose x-rays (about 1/10th the radiation dose of a chest x-ray).

There are two different types of DEXA scans:

  • Central DEXA. While you are lying on a cushioned table, a scanner passes over your lower spine and hip. In most cases you won't need to undress.
  • Peripheral DEXA (p-DEXA). These smaller machines measure the bone density in your wrist, fingers, leg, or heel.

A central DEXA scan that measures bone density in your lower spine or hip is the best test to predict your risk of fractures.

How to Prepare for the Test

Remove any jewelry before the BMD test. Inform your health care provider if you may be pregnant.

How the Test Will Feel

The scan is painless - You will need to remain still during the test.

Why the Test is Performed

Bone mineral density (BMD) tests are used to detect osteoporosis, the thinning of bone tissue and loss of bone density over time.

BMD testing or screening should also be done in the following people, who are thought to be at an increased risk for osteoporosis:

  • Women over age 65 and men over age 70
  • Women under age 65 and men ages 50 - 70 who have risk factors such as:
    • Bone fracture caused by normal activities, such as a fall from standing height or less ("fragility fracture")
    • Chronic rheumatoid arthritis, chronic kidney disease, eating disorders
    • History of hormone treatment for prostate cancer or breast cancer
    • Significant loss of height>2cm
    • Smoking
    • Strong family history of osteoporosis
    • Taking corticosteroid medications (prednisone, methylprednisolone) every day for more than 3 months
    • Three or more drinks of alcohol per day on most days

If you are being treated for osteoporosis, BMD testing can help your health care provider monitor your response to treatment.

Normal Results

The results of your test are usually reported as a "T score" and "Z score."

  • The T score compares your bone density with that of healthy young women.
  • The Z score compares your bone density with that of other people of your age, gender, and race.

In either score, a negative number means you have thinner bones than the standard. The more negative the number, the higher your risk of a bone fracture.

A T score is within the normal range if it is -1.0 or above.

What Abnormal Results Mean

Bone mineral density testing does not diagnose fractures. However, along with other risk factors you may have, it helps predict your risk of having a bone fracture in the future. Your doctor will help you understand the results.

  • A T score between -1 and -2.5 indicates the beginning of bone loss (osteopenia).
  • A T score below -2.5 indicates osteoporosis.

Treatment recommendations depend on your total fracture risk.

Risks

BMD testing involves exposure to a low level of radiation. Most experts feel that the risk is very low compared with the benefits of identifying osteoporosis before you break a bone.

Considerations

Simple bone density scans using portable machines may be available as part of health fairs or screenings. These portable scanners may check the density of your wrist or heel. However, keep in mind that hip and spine scans are more reliable for diagnosis of osteoporosis.