bone density of a femur

Importance of DEXA Scans

I have severe asthma. I was initially diagnosed as a child (at age 8) and I crossed into the severe category when I was 25 years old.  My asthma was quite uncontrolled for most of my late teen and early adult years.  I was one of those unlucky ones with pretty hard to control asthma despite a hefty combination of medications. The medications I need to help keep me breathing also have taken a toll on my body.  Don’t get me wrong, I will choose breathing over the side effects but it can and is pretty darn frustrating at times! Due to years of my asthma being uncontrolled and medications to combat it, my doctor ordered my first bone density test (DEXA scan) when I was 30.  Being on corticosteroids, both inhaled and oral can sometimes lead to loss of bone density over a period of time.

What is a DEXA scan?

DEXA stands for dual energy x-ray absorptiometry.  During the scan, two x-ray beams are aimed at your bones and the three areas most commonly measured are the lumbar spine (lower back), femoral head, and hips, although sometimes the entire body will be scanned.  While a regular X-ray can detect bone density loss to 40%, a DEXA scan can see bone density loss and changes in as little as 1%.

Who should have a DEXA scan?

It is recommended that people who are on medications which are known to cause bone loss such as corticosteroids, some thyroid medications, and some anti-seizure medications.  Anyone with a family history of osteoporosis, have had any fractures that occurred with only mild trauma, some thyroid conditions, and people over 65 years old for women and 70 years old for men.  People with a history of rheumatoid arthritis and low vitamin D levels are also recommended to have a DEXA scan.

What to expect with a DEXA scan?

A DEXA scan is a noninvasive scan and there isn’t much to do beforehand to prepare. It is recommended to not take any calcium supplements for 24 hours before your scan.  Wear loose, comfortable clothing and if possible, wear clothing that doesn’t contain any metal.  No metal zippers, buttons, belts or underwire bras.  You might be asked to change into a patient gown to avoid any potential interference from clothing.  Once in the room with the scanner, you will lay on an x-ray table with your legs and knees supported up on a foam block. Think of it like being in a sitting position on a chair but laying on your back.  It sounds a bit odd but it is really quite comfortable!  The X-ray tube passes over your lower back and pelvis and then your legs are straightened and you are scanned once more.  That’s it!  The whole scan only takes about ten minutes from start to finish.

Interpreting your results

After a radiologist reads the scans your doctor should give you a call and go over your results with you. The way a DEXA scan is reported is with what is called your T-score.  The T-score shows how your bone density is different from a healthy 30-year-old adult.  Normal T-scores range from 4 to -1.  Low bone density (known as Osteopenia) is diagnosed when the T-score is between -1 and -2.4 and you are at an increased risk of fractures.  Osteoporosis is diagnosed when the T-score is -2.5 or less and the fracture risk is high.

I was given my osteopenia diagnosis when I had my first DEXA scan 6 years ago.  Since then I have upped my calcium and vitamin D intake per his recommendations as well as making it a priority to do weight-bearing exercises and walking 3x per week to help prevent further bone loss.  I have to have my DEXA scans repeated every 2-3 years as follow-ups to monitor my bone density.  If you have never had a DEXA scan done, talk with your doctor the next time you are at their office and see if they recommend that you have one done.

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