Bone Density Screening
Dual-energy X-ray absorptiometry
A dual-energy X-ray absorptiometry (DXA) scan is a means of measuring bone mineral density to diagnose osteoporosis (literally “porous bones”). The DXA test can determine if you have normal bone, low bone density (osteopenia), or osteoporosis. It is the only test that can diagnose osteoporosis.
Each year, osteoporosis accounts for 500,000 spinal fractures and 300,000 hip fractures.
Bone loss starts at around age 30 or 35 and is progressive.
Who should have a bone density test?
- Women age 65 or older
- Anyone who breaks a bone after age 50
- Women of menopausal age with risk factors
- Postmenopausal women under age 65 with risk factors
- Men age 50 to 69 with risk factors
What are the risk factors?
- Alcohol abuse
- Early estrogen deficiency
- Family history of osteoporosis
- Gender (one in two women over age 50 will break a bone from osteoporosis)
- Inactive lifestyle
- Loss of height
- Low body weight; being small and thin
- Low calcium intake
- Prolonged use of certain medications
What can a bone density test do?
- Diagnose osteoporosis before you break a bone
- Predict the likelihood of your breaking a bone in the future
- See if your bone density is improving, getting worse, or staying the same
- Find out how well an osteoporosis medicine is working
- Let you know if you have osteoporosis after you break a bone
What other conditions can cause bone loss?
- Breast cancer
- Celiac disease
- Crohn’s disease
- Eating disorders
- Inflammatory bowel disease
- Low testosterone levels
- Malabsorption problems
- Multiple sclerosis
- Organ transplants
- Parkinson’s disease
- Pernicious anemia
- Prostate cancer
- Rheumatoid arthritis
What drugs can cause bone loss?
- Anti-seizure medicine
- Chemotherapy drugs
- Proton pump inhibitors
- Steroids (glucocorticoid), cortisone and prednisone
- Thyroid medicine
How is the test performed?
A DXA test is an easy, outpatient exam that takes approximately 15 to 20 minutes. You will lie on a table while the technologist uses a low-dose X-ray machine to scan your lower back and hip. If you have had back or hip surgery, the technologist may scan your forearm instead. The scan will be given to a radiologist for interpretation.
On the day of the DXA test
You will be asked to fill out a questionnaire to help your physician determine if you have medical conditions or take certain medications that can increase or decrease your risk of osteoporosis.
How to prepare for a DXA test
Wear loose, comfortable clothing. Do not wear garments with zippers, buttons, or metal details. Do not take calcium supplements 24 hours before the exam. If you have had any recent barium exams or have been injected with a contrast material, be sure to inform your physician. You may have to wait 10 to 14 days before having a DXA test.