A DEXA scan is a technique that is used to measure the density of bone mineral. This is one of the most accurate tests available today and is presently the most widely used technique that is used to measure bone density. Doctors, with the help of a DEXA scan, are able to confirm or verify the condition osteoporosis. They are also able to estimate how severe the bone loss is and figure out if your response to the treatment is good.
During the test you will have to lie down on a table while energy is directed rapidly from a scanner towards the bone. This energy comes from two different sources and is directed alternatingly at a frequency that is preset. By using two sources for x-ray energy instead of the radioisotope studies which are traditionally used, doctors are able to obtain results that are precise and accurate.
The DEXA scan results are in the form of T-scores. This statistical measure could be quite complicated and difficult to interpret. It involves comparing your DEXA result with the results of a woman who is healthy and young. With the help of this measure, one is able to quantify how severe the loss of bone mineral is in the skeleton right at the place at which measurements are taken. Most of the DEXA studies measurements are taken at two places, namely the hip and spine.
Your results are normal if your T score is more than -1.0, that is it should be greater than minus 1.0. You are suffering from osteopenia (a milder phase of bone mineral density loss as compared to osteoporosis) if the T score is measured between -1.0 and -2.5. You have osteoporosis at the site that is measured if your T score measurements are -2.5 or less. If your bone mineral density is low then there is an increased chance of fracture. However, just having low bone density does not necessarily mean that you will have a fracture. There are other factors that influence the probability of fracture. For example, the chances of an 80-yr-old woman fracturing her bone after falling down are higher as compared to a healthy 60-yr-old woman who falls down.
You would need to go for a DEXA scan at least once in two years to check the condition of your bones and to find out how effective any therapy has been. You should also ensure that the same machine that was used earlier is used to perform the DEXA scan as it will allow you to accurately compare results.