Key Points about Bone Density Scans

  • Bone densitometry or DEXA (dual-energy X-ray absorptiometry) scans identify a decrease in bone density and a loss of bone strength.
  • DEXA scans determine the risk of broken bones and can confirm a diagnosis of osteoporosis.
  • Radiation exposure during bone densitometry is extremely low, unlike typical X-ray machines.

Candidates for a bone density scan

  • Women age 65 and older, men age 70 and older
  • Postmenopausal women under the age of 65 with one or more the following risk factors: 
  • Family history of osteoporosis (mother or sister) 
  • History of cigarette smoking, excessive alcohol or caffeine consumption 
  • History of diabetes, hyperparathyroidism, or hyperthyroidism 
  • Premature menopause or late onset of menstrual periods 
  • Vitamin D deficiency
  • Long term use of medications known to cause bone loss (i.e., prednisone, seizure medications, diuretics and Depo-Provera contraceptive injections).

Preparing for a bone density scan

Unless instructed otherwise, eat normally on the day of the exam, but avoid taking calcium supplements for at least 24 hours before your appointment. Wear loose, comfortable clothing. Sweat suits and other casual attire without zippers, buttons, grommets or any metal are preferred. You should not have had a barium study, radioisotope injection, oral or intravenous contrast material from a CT scan or MRI for seven days before your DEXA scan.

If you have implanted devices such as pacemaker or infusion pumps, have breast tissue expanders or have religious or cultural concerns, please contact the radiology department before your exam.

What to expect during a bone density scan

During a DEXA scan, you will lie still on a padded table while the DEXA unit scans two or more areas, usually the hip and spine. Unlike typical X-ray machines, radiation exposure during bone densitometry is extremely low, less than the radiation exposure during a coast-to-coast airline flight. The entire process takes only a few minutes to complete, depending on the number of sites scanned. It involves no injections or invasive procedures.

If you need a follow-up exam or second bone density exam, you should receive the scan on the same machine you received it on before in order to receive the most accurate results.