What is a DEXA scan?
DEXA scan - or dual-energy x-ray absorptiometry - is a non-invasive medical test that uses two x-ray beams of low energy, which doctors use to direct towards the bone. By using two separate x-ray beams, it is easier to separate the images of the x-ray into two components: the soft tissue and the bone.
A DEXA scan is used to measure bone density and is known to be a more accurate measure as compared to x-rays as it has the ability to detect the smallest of changes in bone loss.
The results of the scan enable doctors to determine the risk of an individual to develop a fracture and also help in determining the severity of the bone loss.
To assess body composition, the results of the DEXA scan are also helpful in determining the level of visceral fat (the fat stored by the body around certain internal organs).
What is the purpose of a DEXA scan?
DEXA scans are most popularly used to assess the bone density of an individual. This helps in determining if the bones are weak or at any sort of risk of fracture. It is helpful in diagnosing osteoporosis - a health condition whereby the bones become weak, thin, and porous. This leads to an increased risk of fracture, especially in the spinal vertebrae, hip, and some peripheral joints (such as wrists).
To prevent the condition from becoming worse, it is important that osteoporosis is diagnosed as early as possible. This also helps in reducing the risk of fractures.
After a DEXA scan, the doctor usually advises patients to have another scan in a couple of years to check whether the bone density has changed or not.
Who should have a DEXA scan?
The National Osteoporosis Foundation conducted a research in which they stated that males over the age of 70 and females over the age of 65 should have a DEXA scan. The reason for this is that as a person ages, the bones become weak and are exposed to the risk of fractures.
It is also recommended that people who are receiving treatments for osteoporosis should get a scan every one to two years as a follow-up treatment to ensure that the treatment is effective.
Postmenopausal females who are younger than 65 years of age also have the potential risk of low bone density and thus, are recommended to have a scan.
It is recommended for women to undergo the DEXA scan at an earlier age as compared to males as females are known to develop loss of bone density sooner than males do.
Precautions for the scan
While the scan is in process, people are advised to stay still in order to prevent the risk of blurry images. The scan is known to be painless and takes up to a maximum of 30 minutes.
DEXA scan is known to be safe, but due to the x-rays, it has the potential of exposing you to radiation. Women who are pregnant are highly recommended to consult a doctor before the scan as it may not be advisable for them to undergo the scan.
Results of the DEXA scan
The DEXA scan results are analyzed through a system called a T-score. The T-score is analyzed by comparing the bone density of a relatively healthier adult of the same gender.
According to the World Health Organization (WHO), the definitions of bone density levels are given below:
1. T-score of -1.0 or above – normal bone density level
2. T-score of -1.1 to -2.4 – osteopenia: low bone density level
3. T-score of -2.5 or lower – osteoporosis: very low bone density level which needs to be diagnosed