Interpretation of DEXA Scan Results

The results of a DEXA scan are presented as T-scores. This is quite a complicated statistical measure. It refers to a comparison in measure of the individual woman’s DEXA result with that of a healthy young woman’s results (when peak bone mass is at its best).

The important aspect of this measure is that it provides a means of quantifying the severity of bone mineral loss (loss of bone mineral density) in the skeleton at the site at which it is measured. It is the loss of bone mineral density that leads to osteoporosis.

There are however, stages in the progression of bone mineral density loss that eventually lead to osteoporosis. The majority of DEXA studies measure bone mineral density at two sites – the hip and spine.

	DEXA Results34
	Normal Osteopaenia Osteoporosis A normal bone density is when the T score measures greater than –1.0 (greater than minus 1.0) If the bone mineral density is measured as a T score between  –1.0 and –2.5 (minus 1.0 and minus 2.5) this indicates the presence of osteopaenia. Osteopaenia is not osteoporosis. It does however indicate that there is a reduction in bone mineral density, which is not as severe as osteoporosis. This condition represents an earlier phase of bone mineral density loss in the skeleton. If the bone mineral density is measured as a T score of –2.5 or less (minus 2.5 or less) this indicates the presence of osteoporosis at the site of measurement.

It is important to realise that a low bone mineral density measure is associated with an increased risk of fractures.³⁴ However, even when a woman does have a finding of a low bone density on a DEXA scan, it does not mean she is going to have a fracture. Other factors influence the likelihood of fracture, not just the bone mineral density reading on a DEXA scan.³⁵

For instance a woman with osteoporosis on a bone DEXA scan in her 50’s or 60’s who is healthy is less likely to have a fracture than the woman with osteoporosis on a bone DEXA scan, who is in her 80’s and has a tendency to fall due to other medical conditions.

Who should have a DEXA scan?

People who have an increased risk of osteoporosis should talk to their doctor about having a DEXA scan.

A doctor’s referral is required for a DEXA. Not all people will be eligible for the full Medicare rebate.

The cost of a DEXA scan is approximately $85.00. This figure may vary depending on where the test is performed. There are specific indications that allow for a Medicare rebate. These include

• People aged 70 years and over (available 1 April 2007)
• 1 or more fractures occurring after minimal trauma
• Monitoring of low bone mineral density proven by previous bone DEXA
• Prolonged steroid therapy
• Female hypogonadism (oestrogen deficiency) lasting more than 6 months before age of 40.
• Male hypogonadism (testosterone deficiency)
• Primary hyperparathyroidism
• Chronic liver disease
• Chronic kidney disease
• Proven malabsorption disorders eg coeliac disease
• Rheumatoid arthritis
• Hyperthyroidism

Frequency of DEXA scan

Generally your doctor will arrange for you to have a repeat DEXA scan every two years to monitor the status of your bones or assess the effects of therapy. It is also important to have the DEXA scan performed on the same machine so as to allow for accurate comparison of results.

Content updated February 2006