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Bone Density Test1

Bone Density Test1

Definition

In the past, osteoporosis could be detected only after a bone fracture. By that time, it is too late and your bones could already be quite weak. A bone density test makes it possible to know your risk of fracture before the fact.

A bone density test is a non-invasive test that uses X-rays to determine if you need to improve your bone health. The bones that are most commonly tested are usually the hip and spine.

Bone density tests are not the same as bone scans as they require an injection beforehand and are usually used to detect fractures and other abnormalities in the bone.

Regardless of your sex or age, your doctor may recommend a bone density test. Bone density tests are easy, painless and virtually no preparation is needed.

What You Can Expect

Bone density tests are usually done on bones that are most likely to break because of osteoporosis, including:

  • Lower spine bones (lumbar vertebrae)
  • The narrow neck of your thighbone (femur), next to your hip joint
  • Bones in your forearm

Results

T-score

The bone densitometry test determines the Bone Mineral Density (BMD). Your BMD is compared to two norms--healthy young adults (your T-score) and age-matched (your Z-score).

T-score is your bone density compared with what is normally expected in a healthy young adult of the same sex.

T-score What your score means
1 to -1 Bone density is considered normal.
Between -1 and -2.5  Bone density is below normal and may lead to osteoporosis.
-2.5 and below Bone density indicates the bone is affected with osteoporosis.

Z-score

Z-scores are calculated the same way but comparisons are made to someone that is the same age, gender, ethnicity, height and weight.

References: 
1. Osteoporosis Australia (2014).About Osteoporosis – Diagnosis.Available at http://www.osteoporosis.org.au/diagnosis[Accessed 16 March 2016.]