Bone Density Scan

Osteoporosis, which means "porous bones," is a bone-thinning disease that can lead to debilitating fractures, typically in the spine, hip and wrist. Although the condition is often considered a "women's disease," men also are affected. In the United States, an estimated 10 million people already have the condition and almost 34 million more have low bone mass, placing them at increased risk for osteoporosis. Of the 10 million Americans estimated to have osteoporosis, 8 million are women and 2 million are men.

Many people don't know they have osteoporosis until they have a fracture or have a bone density scan, also known as a bone mineral density (BMD) test. A bone density scan is a simple, non-invasive test that measures a person's bone density or volume of calcium and minerals within bone tissue. Bone density scans are available at the UCSF Medical Center and can help to:

  • Detect osteoporosis before a fracture occurs
  • Predict your chance of fracturing in the future
  • Determine your rate of bone loss or monitor the effects of treatment

Who Should Have One

Your doctor can help determine if you should have a bone density scan. They are recommended if you are age 65 or older regardless of risk.

If you're under 65 years of age, you should have a bone density scan if you have one or more of the following risk factors:

  • Calcium-deficient diet
  • History of amenorrhea, the abnormal absence of menstruation
  • History of malabsorption
  • Moderate to high alcohol intake
  • Poor nutrition
  • Postmenopausal
  • Prolonged treatment with steroids, certain anti-cancer drugs, thyroid hormone and some anti-seizure medications
  • Sedentary lifestyle
  • Significant caffeine consumption
  • Small-boned frame
  • Smoker


A bone density scan is a simple, non-invasive and painless exam to measure bone mass in areas such as your spine, hip, wrist, finger, kneecap, shin bone and heel. The standard test uses a low dose X-ray to detect signs of bone thinning and mineral loss.

The scan measures the density of the spine and hip. The forearm is measured in people with hyperthyroidism or if either hip cannot be scanned. Some doctors will order just a hip scan as a screening study for patients under the age of 60.

There are several machines that measure bone density. Central machines measure density in the hip, spine and total body. Peripheral machines measure density in the finger, wrist, kneecap, shin bone and heel. At the UCSF, we offer screening with both central and peripheral machines, as well as ultrasound examinations of the heel to determine your risk for fractures.

A bone density scan, using a central machine, takes about 15 minutes, including registration. During the procedure, you will lie on a table scanner for five to eight minutes. A technologist will sit next to you throughout the procedure.

In addition to the standard scan, a CT bone density scan uses computed tomography to measure bone density. These scans provide detailed, 3-D images and can measure the effects of aging and diseases other than osteoporosis on your bones. For a CT test, you lie on a table that moves into a large tube-like area where images are taken. It typically takes about 10 minutes.


A bone density scan requires little preparation. You may eat normally and take medications as prescribed by your doctor the morning of your test.

The only restrictions are:

  • Do not take any vitamin pills or mineral supplements the morning of your exam.
  • You must not have any exams involving barium or radioisotopes within the last month. These scans interfere with the bone density results.


The results of your bone density scan will be available within three to five days. This information will enable your doctor to determine if you're at risk for fractures and require further evaluation. The lower your bone density, the higher your risk for fracture. Test results also help you and your doctor plan the best course of action for your bone health.

More Information

Standard bone density scans, using X-rays, are performed by Radiology at UCSF Medical Center's Parnassus campus:

UCSF Ambulatory Care Center
400 Parnassus Ave.
Third Floor
San Francisco, CA 94143
Phone: (415) 353-2666
Fax: (415) 353-2587
Hours: Monday to Friday, 8:45 a.m. to 5 p.m.

Bone density scans using a CT scanner are performed at UCSF Medical Center's China Basin facility:

UCSF China Basin Imaging Center
185 Berry St.
Lobby 7, Suite 190
San Francisco, CA 94107
Phone: (415) 353-2573
Fax: (415) 353-4522
Hours: Monday to Friday, 7:30 a.m. to 6:30 p.m.