Bone Density Scan

A bone density scan, also known as a DEXA or DXA scan, is a low-dose x-ray that measures calcium and other minerals in your bones. Bones containing more minerals are denser and tend to be stronger and less likely to break. The measurement helps show your bone's strength and thickness (known as bone density or mass).

Your bones usually become thinner as you get older or if you develop certain medical conditions. When bones become thinner than usual, it's known as osteopenia. Osteopenia puts you at risk for a more serious condition called osteoporosis.

Osteoporosis is a disease that causes bones to become very thin and brittle. It gets worse over time. It usually affects older people and is most common in women over the age of 65.

People with osteoporosis are at higher risk for fractures (broken bones), especially in their hips, spine, and wrists.

Why this test is done

Most women age 65 or older should have a bone density scan. Women in this age group are at high risk of losing bone density, which can lead to fractures. Women of other ages and men may also be at risk for losing bone density if they:

• Have a very low body weight
• Have had one or more fractures after the age of 50
• Have lost a half inch or more in height within one year
• Have a family history of osteoporosis

Other risk factors for losing bone density include:

• Lack of physical activity
• Long-time use of tobacco or alcohol
• Not getting enough calcium and vitamin D in your diet
• Having medical conditions such as diabetes or rheumatoid arthritis
• Being an older male with risk factors for weak bones or osteoporosis

How to prepare

You may be told to stop taking calcium supplements 24 to 48 hours before your test. You should also avoid wearing metal jewelry or clothes with metal parts, such as buttons or buckles.

Other names for this test

bone mineral density test, BMD test, DEXA scan, DXA; Dual-energy x-ray absorptiometry scan, Bone densitometry, Dual x-ray absorptiometry, DXA