Bone health and HIV disease

February 2008     View PDF     En español

How is bone loss diagnosed?

Unfortunately, many find out they have bone loss only after they’ve fractured or broken a bone. To detect bone loss before this happens, several bone density tests are available. Most are painless and they vary in cost and length of time to take. However, there are no standards of care for using them in people with HIV. In general, the longer you’ve lived with HIV and the more risk factors you have, the more likely bone tests may be needed.

DEXA scan
The DEXA (dual energy x-ray absorptiometry) scan is a kind of x-ray and is the most common and accurate way to measure BMD. It can detect as little as 2% of bone loss per year, and it uses only 10% of the radiation used in a routine x-ray. It’s painless and takes 10–15 minutes.

CT scan
The CT (computer tomography), or CAT, scan uses x-rays and a computer to make images of the bone. It can detect osteopenia, osteoporosis and osteonecrosis. The scan is painless and gives more detail than an x-ray, though it uses radiation. A scan can last from 5–30 minutes.

X ray
A standard x-ray is not useful in diagnosing osteopenia or osteoporosis because it’s not sensitive enough to detect minor bone loss. It’s used mostly to detect osteonecrosis, showing the amount of severe damage to the bone. An x-ray is painless and quick to take, though it uses radiation.

MRI
The MRI (magnetic resonance imaging) scan can detect osteopenia, osteoporosis and osteonecrosis. It uses magnets and radio waves to create detailed pictures of the bone. It’s painless and can last up to 45 minutes. An MRI does not use radiation like an x-ray or CT scan.

Bone biopsy
A biopsy is usually done to detect osteonecrosis. A sample of bone is removed during surgery or with a needle and local anesthesia. This is an invasive test that takes time, causes discomfort, and may need recovery time.

Bone density test results
Your test result is written as a T-score and Z-score. The T-score compares women and men to a “normal” healthy person of their own sex. A normal T-score, or healthy bone density, is a number above -1.0. A score for osteopenia will be between -1.0 and -2.5, while osteoporosis is less than -2.5.

The Z-score compares your BMD to someone of your own age, sex, weight and ethnic origin. This can provide helpful information for your doctor as well. A T-score is better used for detecting osteoporosis.