What Should You Wear for a Bone Density Test?

Wear lightweight, loose-fitting clothing with no metal components. A cotton T-shirt and elastic-waist sweatpants or athletic shorts are the gold standard for a bone density test, also called a DXA scan. The machine works by passing two low-dose X-ray beams through your body, and anything dense or metallic in the scan field can throw off the reading. Getting dressed correctly before you leave the house can save you the hassle of changing into a hospital gown at the clinic and, more importantly, help ensure your results are accurate.

How a DXA Scan Actually Works and Why Clothing Matters

A DXA (dual-energy X-ray absorptiometry) scanner generates X-rays at two different energy levels. It uses the difference in how those two beams pass through your body to separate bone from soft tissue and calculate your bone mineral density.¹ The math behind this separation is precise, and it assumes that the only things in the scan field are your bones and your soft tissue. Anything else sitting between you and the X-ray beam, whether it is a metal zipper, a thick layer of denim, or a reflective safety strip on workout gear, creates a false signal the scanner cannot distinguish from actual bone or tissue. These false signals are called artifacts, and they can nudge your bone density score up or down enough to matter clinically.²

The stakes here are not trivial. Your doctor uses your DXA results to decide whether you need treatment for osteoporosis, whether a medication is working, or whether your bone loss is progressing. A small artifact that bumps your score by even a percent or two could mask real bone loss between scans, or falsely suggest a problem where there is none. The easiest artifacts to eliminate are the ones you carry in on your body.

Fabrics That Can Skew Your Results

Not all clothing fabrics are equal in the eyes of a DXA scanner. A study that directly tested how different textiles affect scan results found that polyester fabric with a reflective strip consistently altered bone density and body composition measurements. That single fabric type raised the average lumbar spine bone mineral density reading and also shifted body composition numbers, decreasing measured fat mass by about 173 grams and increasing lean mass by about 213 grams.³ Those numbers sound small, but in serial monitoring where your doctor is watching for changes over months or years, they can be enough to obscure real trends or create false ones.

The same study found that several other fabrics also caused measurable shifts. Metallic thread, wool, denim blends, and shiny polyester all altered fat and lean mass readings. Even cotton denim and standard sweatshirt material affected lean mass measurements. The researchers concluded plainly that clothing made of dense textiles like wool and denim, or anything with reflective material or metallic thread, should be avoided during a DXA scan.³

The practical upshot is that your thickest, heaviest everyday clothing is the most likely to cause problems. Jeans are probably the most common offender because they are dense, often have metal rivets and zippers, and many people wear them without thinking twice. Wool sweaters, heavy knits, and any athletic wear with reflective safety strips (common on running jackets and cycling gear) also belong on the “leave at home” list.

Metal, Zippers, and Accessories

Metal is the most reliable way to ruin a DXA scan. Zippers, buttons, snaps, belt buckles, underwire bras, safety pins, and jewelry all show up clearly on the scan and create bright spots the software may interpret as bone. Even small metallic objects can be problematic. Research looking at surgical clips (tantalum clips left over from operations) found that all metal clip types were visible on single-energy scans as bright white objects.⁴ If tiny surgical clips inside your body show up, the metal snap on your waistband certainly will too.

Before your appointment, do a quick mental inventory of everything you plan to wear and carry:

Remove: necklaces, body piercings (if removable), belly button rings, watches, bracelets, and any hair accessories with metal clips if you are having a skull or total-body scan.
Avoid wearing: jeans or pants with metal zippers or rivets, bras with underwire or metal hooks, belts with metal buckles, and shirts or jackets with metal snaps or decorative studs.
Check pockets: coins, keys, phones, and even foil-wrapped items in your pocket will show up on the scan.

Some clinics will let you leave metal items on if they are far from the area being scanned. If only your hip and spine are being measured, a metal watch on your wrist is not a concern. But for a total-body scan, everything matters. When in doubt, take it off.

The Ideal Outfit

The simplest approach is to dress for the appointment the way you would dress for a casual gym session. A plain cotton T-shirt or lightweight athletic top without reflective strips, paired with elastic-waist sweatpants, athletic shorts, or leggings works well. Skip anything with logos printed in metallic ink or reflective material. Cotton and thin synthetic blends that do not have any special coatings are your safest choices.

For undergarments, a soft sports bra or bralette without underwire and without metal clasps is ideal. If your only bra has underwire, plan to remove it before the scan or ask the clinic for a gown. Cotton or synthetic underwear without metal or decorative elements is fine to wear.

Shoes do not matter for a standard hip-and-spine DXA because they will not be in the scan field. You will likely be asked to remove them anyway just to lie comfortably on the table. For a total-body scan, you will definitely take them off.

If you forget and show up in jeans and a belt, most clinics keep hospital gowns on hand. It is not the end of the world, just an added step. Some facilities will ask you to change regardless of what you are wearing, so calling ahead to ask about the dress code is always reasonable.

Compression Garments and Specialty Wear

People who wear compression garments for medical or personal reasons should know that some of these can affect scan accuracy. Compression stockings with graduated pressure, post-surgical compression wraps, and body-shaping undergarments are all denser than typical clothing and may contain elastic components or reinforced panels thick enough to register on the scan. If you wear a compression garment daily for a medical condition such as lymphedema or deep vein thrombosis, mention it to the technologist before the scan begins. They can advise whether to remove it or note its presence so the reading is interpreted correctly.

The same logic applies to chest binders, which are typically made of thick, tightly woven synthetic material. If you wear a binder, removing it for the few minutes the scan takes will give cleaner results. A technologist should be able to accommodate privacy needs during this process.

Calcium Supplements and Other Preparation You Might Not Think About

What you swallowed that morning can matter as much as what you are wearing. Calcium tablets sitting in your stomach or intestines during a lumbar spine DXA scan can show up in the scan field and artificially inflate your bone density reading. One study found that about a third of participants showed bone density changes outside the clinically meaningful threshold within 30 minutes of taking a calcium supplement, and the researchers recommended that patients skip their calcium tablet before a spine DXA.⁵

A separate study explored the mechanics of this in more detail. It found that a single undissolved 500-milligram calcium tablet overlying the scan area had a relatively small effect on the overall lumbar spine score, generally changing it by around 2% or less. That sounds reassuring until you consider edge cases: when fewer vertebrae are available for measurement (because of prior fractures, spinal hardware, or severe arthritis in certain segments), a single tablet overlying one vertebral body could shift the reading by as much as roughly 13%, which is enough to misclassify your bone health entirely.⁶ The effect was also larger in people with lower baseline bone density, precisely the population where accurate measurement matters most.

The safe move is to hold off on calcium supplements the morning of your scan and take them afterward instead. This is a simple precaution that costs you nothing. Some clinics will mention this when they schedule the appointment, but many do not, so it is worth knowing on your own. Other supplements and antacids that contain calcium, such as certain chewable heartburn tablets, fall into the same category.

What About Internal Metal and Prior Surgeries

If you have metal inside your body from a previous surgery, like a hip replacement, spinal fusion hardware, screws, plates, or even small surgical clips, that is a different situation from wearing metal on your clothing. You cannot remove internal hardware, and DXA technologists know how to work around it. Typically, the side with the implant is excluded from measurement, and the scan is done on the opposite hip or on a forearm instead. Spinal hardware in the lumbar spine may mean your doctor relies more heavily on hip measurements for monitoring.

Small surgical clips, even ones much tinier than a joint replacement, do show up on DXA scans and can create artifacts that either inflate or falsely reduce the bone density reading at that spot.⁴ If you have had abdominal surgery, gallbladder removal, or any procedure that might have left clips behind, let the technologist know before the scan. They can use single-energy imaging to check for clips and adjust the analysis if needed.

Pacemakers, port-a-caths, and other implanted medical devices are generally not a problem because they are either outside the scan region or can be accounted for in the analysis. Unlike an MRI, DXA uses X-rays rather than magnets, so there is no safety concern with metal implants during the scan itself. The only question is whether the device will distort the measurement, and that depends on where it sits relative to the area being scanned.

Transdermal Patches and Wearable Devices

Medication patches stuck to your skin, like hormone patches, nicotine patches, or pain relief patches, can occasionally appear on a DXA scan depending on their composition and placement. Most thin patches are not a problem, but patches with a metallic backing or thicker adhesive layers could theoretically create a small artifact if they happen to sit directly in the scan path. The practical advice is simple: if the patch is on your lower back, hip area, or abdomen and you are having a spine or hip scan, mention it to the technologist. They may ask you to move it temporarily.

Continuous glucose monitors and insulin pump infusion sites are increasingly common and are generally too small and too far from the spine or hip to cause an issue. But during a total-body scan, any device stuck to your skin becomes part of the picture. Let the technologist know about anything attached to your body so they can note its position.

Why Consistency Between Scans Matters More Than Perfection

If you are getting a DXA scan for the first time, wearing the right clothing ensures the most accurate possible baseline reading. But if you are coming back for a follow-up scan to track changes over time, consistency becomes the critical factor. Ideally, you would wear the same type of clothing, hold the same supplements, and scan at the same facility on the same machine. DXA machines from different manufacturers can give slightly different readings, and even the same machine can produce small variations depending on how you are positioned.

The reason consistency matters is that doctors are often looking for changes as small as 2 to 3 percent between scans. If your first scan was done in a hospital gown and your second in jeans, any apparent change in bone density could be partly or entirely an artifact of the clothing difference rather than an actual change in your bones. Dense fabrics like denim can raise the measured bone density slightly, as the textile research showed, which could mask real bone loss or exaggerate apparent improvement.³

This is also worth thinking about if your DXA includes body composition analysis, which many total-body scans now do. The textile study found that certain fabrics shifted fat and lean mass readings by hundreds of grams in opposite directions. If you are using DXA body composition to track fitness progress or to monitor a medical condition, wearing different clothing at each scan introduces noise that makes it harder to detect real changes.

What Happens if an Artifact Slips Through

Even with careful preparation, artifacts sometimes appear on DXA scans. A forgotten belly button ring, an undissolved supplement tablet, or a fabric element you did not realize was reflective can all show up. Good DXA technologists and the physicians who interpret the scans are trained to spot common artifacts. Modern DXA software can identify some objects in the soft tissue field and exclude them from the analysis automatically. In the calcium tablet studies, newer software versions successfully flagged tablets in the soft tissue area as artifacts and removed them from calculations.⁶ However, when an object overlaps bone and soft tissue simultaneously, the software has a harder time, and the technologist may need to manually adjust the scan boundaries or exclude the affected area.

The quality of artifact detection varies between facilities. High-volume bone density centers that scan dozens of patients a week tend to have more experienced technologists who catch problems quickly. A facility that does only occasional DXA scans may miss subtler artifacts. If you are choosing where to get your scan, asking how many DXA scans the facility performs and whether a trained densitometry technologist will be operating the machine is a reasonable question. The scan itself takes only about 10 to 20 minutes, is painless, and involves a very low dose of radiation. Dressing appropriately is the single easiest thing you can do on your end to help the process go smoothly.