Test Overview

Bone mineral density (BMD) is a test that measures the amount of calcium in a specific region of the bones. From this information, an estimate of the strength of your bones can be made.

Minerals (such as calcium) are constantly being added to and taken away from bone. When minerals are taken away faster than they are added, the bones become lighter, less dense, and more porous. This makes the bones weaker and increases their risk of fracture.

Bones naturally become thinner (called osteopenia) as you grow older, because existing bone is broken down faster than new bone is made. As this occurs, the bones lose minerals (such as calcium), heaviness (mass), and structure, making them weaker. With further bone loss, osteopenia develops into osteoporosis. The thicker your bones are, the longer it takes to develop osteoporosis. Although osteoporosis can occur in men, it is most common in women who have gone through menopause.

Ordinary X-rays cannot detect mild bone loss. A bone must lose at least a quarter of its weight before a standard X-ray can detect the problem.

Bone density measurements can be done on several bones in the body. Controversy exists over which bones are best to use for BMD measurements. The bones most commonly used are those in the lower spine and hip. These bones generally have the greatest amount of bone loss and are at the highest risk of fracture. In special cases, bones in the wrist may be used for BMD measurements.

You can click on the following links for more information or click on the Health Encyclopedia.
Bone Density Test