Osteoporosis

What is a DEXA exam?

DEXA bone density testing serves as an aid in diagnosing osteoporosis, osteopenia (low bone density), and in monitoring the effectiveness of treatment. The DEXA bone densitometer uses a small amount of radiation to produce images of the spine and hips. The spine and hips are measured because that is where osteoporotic fractures occur most frequently.

What is a bone density test?

A bone mineral density test measures possible bone loss.  DEXA (Dual Energy X-ray Absorptiometry) is a type of bone-mineral density test and is considered the "gold standard" in accuracy and precision of bone-density measurement.  The X-ray uses two energy levels.  Bones absorb each level differently, and a computer is able to calculate this difference and use it to determine bone density.  Bone density measurements focus on bones in the lower spine and both hips, since that is where most osteoporotic fractures occur.

Why do we measure bone density with DEXA?

A healthy exterior appearance does not accurately reflect the strength of the bones underneath. While there are many risk factors associated with the development of osteoporosis, the greatest risk is low bone density. Bone density testing is the best way to detect osteoporosis and can help predict risk of fracture.

How much radiation will I receive?

The amount of X-ray absorbed by the patient is only about 1/10^th of that received from a chest X-ray.

What can I expect from the exam?

A bone density exam is a simple and comfortable procedure.  The bone densitometer looks like a large, padded examination table.  The technologist will enter your name, height, weight, age and ethnicity into the computer before your exam.  This information is used to compare your results to a normal reference group.

In most case you will remain in your normal clothing, but metal jewelry, belt buckles, and metal or thick plastic buttons will need to be removed from the area being scanned.  You will be asked to lie on your back.  The technologist will position your arms and legs.  The test is painless and takes less than ten minutes.

What will the test results tell my health-care provider?

A computer analyzes results from the DEXA test by determining how much bone mineral is present. Results are given numerically and graphically and are reported as a T-score and a Z-score.

A T-score result compares your bone density to that of the young adult control group and determines your fracture risk, which increases as your bone density falls below normal:

 

 

          A normal T-score is above -1

 

 

 

          An osteopenic result is a T-score between -1 and -2.5

 

 

 

          An osteoporosis result is a T-score that is below -2.5

A Z-score compares your results to people of the same age and body size. Since low bone density is common in older adults, the Z-score can be misleading.  Doctors will utilize the T-score in making treatment decisions.

Your health-care provider might prescribe medication to treat the bone loss identified in your DEXA exam. A repeat DEXA exam in one to two years can help monitor the effectiveness of your treatment.

How do I schedule a DEXA exam?

Discuss your concerns about osteoporosis with your health-care provider and obtain an order for the exam. Then call the Mercy Women’s Center at 319-398-6821 to schedule the exam.