A bone density test typically takes 10 to 30 minutes, depending on how many areas of your body need scanning. The full appointment, including check-in and positioning, usually wraps up within about 30 minutes. It’s one of the fastest and simplest imaging tests you can get.
Central DXA vs. Peripheral Scans
The standard bone density test is called a central DXA scan, performed at a hospital or imaging clinic. It measures density in the bones most vulnerable to osteoporosis: the lower spine, the neck of the thighbone near the hip joint, and sometimes the forearm. You lie on a padded table while a scanning arm passes over your body. The actual scan takes 10 to 30 minutes, with shorter times when fewer sites are being measured.
Peripheral scans are a quicker alternative that measures bone density in your finger, wrist, or heel using a small portable machine. These take just a few minutes and are commonly offered at health fairs, pharmacies, and mobile health vans. They’re useful as a screening tool but aren’t as comprehensive as a central DXA, which remains the gold standard for diagnosing osteoporosis.
What Happens During the Test
There’s no injection, no enclosed tube, and no discomfort. You lie flat on an open table, fully clothed, while the machine directs a very low dose of X-ray energy through the target bones. The radiation exposure is tiny, in the range of 0.001 to 0.01 millisieverts, which is a fraction of what you’d receive from a standard chest X-ray. You won’t feel the scan at all. A technologist may reposition your legs or arms between scans of different body sites, which is why the total time varies.
How to Prepare
Preparation is minimal, but a few things matter for accurate results. Stop taking calcium supplements, antacids containing calcium, vitamin D, and multivitamins for 24 hours before your appointment. You can still eat calcium-rich foods normally. Wear loose, comfortable clothing without metal buttons, zippers, or metallic threads, and skip the underwire bra. Remove any body piercings below the neck if possible, since metal interferes with the scan’s accuracy.
When You’ll Get Results
Your results are reported as a T-score, which compares your bone density to that of a healthy 30-year-old. The scale is straightforward:
- T-score of -1 or higher: healthy bone density
- T-score between -1 and -2.5: osteopenia (mild bone loss)
- T-score of -2.5 or lower: osteoporosis
Each single-point drop in T-score increases fracture risk by 1.5 to 2 times, so small differences on this scale carry real clinical weight. Most providers share results within a few days to a week, though some offices discuss preliminary findings the same day.
Who Should Get Tested and How Often
The U.S. Preventive Services Task Force recommends routine bone density screening for all women 65 and older, and for postmenopausal women under 65 who have elevated fracture risk from factors like low body weight, smoking, family history of osteoporosis, or long-term steroid use. For men, there isn’t enough evidence yet for a blanket screening recommendation, though doctors may order the test based on individual risk factors.
Once you’ve had your first scan, repeat testing is generally done every 24 months. Medicare covers it on that schedule for people who meet certain conditions. Your doctor may recommend more frequent testing if you’re being treated for osteoporosis or have a condition that accelerates bone loss.