A bone density test typically takes 10 to 30 minutes for the scan itself. The most common version, a central DEXA scan of the hip and spine, falls in that range. A peripheral scan of the heel or wrist takes only a few minutes. With check-in and preparation, most people are in and out of the appointment in under an hour.
What Happens During the Scan
A DEXA (dual-energy X-ray absorptiometry) scan is the standard bone density test. You lie on a padded table while a scanning arm passes over your body, measuring bone mineral density at the hip and spine. You don’t need to hold your breath or stay perfectly still in any uncomfortable position. The machine does the work while you lie flat. There’s no injection, no enclosed tube, and no noise. It feels like getting an X-ray, just slower.
The 10-to-30-minute range depends on the equipment your facility uses and whether the technologist needs to reposition you between scans of different body sites. Newer machines tend to be faster. If only one area is being scanned, you’ll be closer to the 10-minute end.
Peripheral bone density tests, sometimes offered at health fairs or pharmacies, measure density at the heel, wrist, or finger. These take just a few minutes and use a small portable device. They’re useful as a quick screening but aren’t as comprehensive as a central DEXA scan, which remains the gold standard for diagnosing osteoporosis.
How to Prepare
Preparation is minimal, which is part of why the appointment is so quick. Wear loose, comfortable clothing without zippers, belts, or buttons. Leave jewelry at home and empty metal objects like keys or coins from your pockets. Some facilities will ask you to change into a gown, but many won’t if your clothing is metal-free.
One preparation step worth noting: many DEXA centers advise patients to stop taking calcium supplements for 24 hours before the scan. Undigested calcium tablets can show up as an artifact on the image and potentially skew your lumbar spine results. Regular dietary calcium from food is fine. If you take a daily calcium supplement, just skip the dose the day before your appointment.
Radiation Exposure
DEXA scans use X-rays, but the radiation dose is extremely low, typically between 0.001 and 0.01 millisieverts. For context, a standard chest X-ray delivers about 0.1 millisieverts, roughly 10 to 100 times more than a bone density scan. You won’t need a lead apron, and there’s no waiting period or precaution needed afterward.
Understanding Your Results
Your results come back as a T-score, which compares your bone density to that of a healthy 30-year-old adult at peak bone mass. The World Health Organization sets the thresholds: a T-score of negative 1 or higher is normal, between negative 1 and negative 2.5 indicates osteopenia (mildly low bone density), and negative 2.5 or lower suggests osteoporosis. Results are typically available within a few days, though some clinics share them at a follow-up visit.
If you’re younger than 50 or premenopausal, your report may also include a Z-score, which compares your density to others your age rather than to peak bone mass. This helps distinguish between expected age-related bone loss and something that warrants further investigation.
Who Should Get Tested
The U.S. Preventive Services Task Force recommends bone density screening for all women aged 65 and older. Postmenopausal women younger than 65 should be screened if they have risk factors for fractures, such as a family history of osteoporosis, low body weight, smoking, or long-term steroid use. A clinical risk assessment tool can help determine whether early screening makes sense.
For men, there isn’t enough evidence yet for a universal screening recommendation. Clinicians generally use their judgment based on individual risk factors like age, medications, and fracture history. Men with known risk factors, particularly those who have taken corticosteroids long-term or have low testosterone, are often referred for testing.
Follow-up scans are usually repeated every one to two years if you’ve been diagnosed with osteopenia or osteoporosis, or if you’ve started treatment and your doctor wants to track whether your bone density is improving or stable.