A DEXA scan needs very little preparation. You can usually eat normally, but you should skip calcium supplements for at least 24 hours, wear loose clothing with no metal, and tell the technologist about any recent barium or contrast exam, any chance of pregnancy, and any spine surgery. RadiologyInfo.org lists all of these in its patient guide.
The rest of this guide covers each step, the mistakes that most often cause a delayed or less reliable scan, and what to do if you want to compare results over time.
TL;DR
- Eat and drink normally on scan day unless your provider tells you otherwise. Fasting is generally unnecessary.
- Stop calcium supplements at least 24 hours before. Some facilities ask for up to 48, so check your appointment instructions.
- Wear loose, comfortable clothes with no metal zippers, buttons, buckles or underwire. Leave jewelry at home.
- Tell the scheduler if you recently had a barium study or a CT or nuclear scan with contrast. You may need to wait 10 to 14 days.
- Say so if you might be pregnant, or if you have had spine surgery, scoliosis or severe arthritis.
Table of Contents
- The short answer: how much prep does a DEXA scan need?
- Calcium and supplements
- Do you need to fast?
- What to wear to a DEXA scan
- Recent contrast, barium or nuclear medicine exams
- Pregnancy
- Tell the technologist about your spine and joints
- A day-before checklist
- What happens during the scan
- Choosing where to have the scan
- Making sense of your results
- Our perspective: the scan is the start, not the plan
- If you want to act on your results
- FAQ
- Sources
The short answer: how much prep does a DEXA scan need?
Almost none. Mayo Clinic describes a bone density test as easy, fast and painless, with almost no preparation needed. The scan measures bone density, usually in the hip and spine, using a low dose of x-rays. You lie on a padded table while an arm passes over you. There are no needles, and you should not feel pain.
What preparation there is has one purpose: keeping anything out of the x-ray path that could distort the measurement. That includes metal, supplement tablets still in your gut, and leftover contrast material from another exam. Once you see that, the rules are easy to remember.
Calcium and supplements
This is the rule most people forget.
RadiologyInfo.org advises against calcium supplements for at least 24 hours before your DEXA exam, and notes that some institutions ask you to stop for up to 48 hours. The reasoning is simple: a calcium tablet that hasn’t been absorbed can sit in the digestive tract in front of your spine and show up on the image as something dense. That can make the reading less accurate.
In practice:
- Check your appointment letter first. Your facility’s rule outranks any general guide.
- Skip the dose, not the habit. Skip your calcium on the day before and the morning of the scan, or for the period the facility gives. Resume afterward.
- Look at multivitamins and antacids. Many contain calcium. Some facilities ask you to avoid multivitamins too. If you aren’t sure whether a product counts, ask when you confirm the appointment.
- Don’t change prescription medicines on your own. If you take osteoporosis medication, keep taking it as prescribed unless your doctor tells you to do otherwise.
Do you need to fast?
Usually not. Cleveland Clinic says fasting is generally unnecessary for a DXA scan unless your provider specifically instructs it. The one catch: if you are having other imaging or blood work on the same day, those may have their own fasting rules. Ask about each one separately.
That also answers a common worry about drinking water. Normal eating and drinking before a bone density scan is fine under the guidance above. You don’t need to arrive thirsty or on an empty stomach.
What to wear to a DEXA scan
Wear something you could comfortably lie flat in for a few minutes. RadiologyInfo.org recommends loose clothing without metal zippers, buttons, belts or buckles, and says to remove jewelry, dental appliances and eyeglasses if they are in the scanned area. Some facilities may ask you to change into a gown.
| Good choices | Avoid |
|---|---|
| Elastic-waist pants or leggings with no hardware | Jeans with metal rivets, zippers or buttons |
| Soft cotton or knit tops | Bras with underwire, tops with metal clasps or snaps |
| Slip-on shoes | Belts, buckles, decorative hardware |
| Plain socks | Necklaces, watches, keys or a wallet in pockets |
The goal isn’t modesty rules. It is to keep metal out of the hip and spine area so you don’t have to undress and the scan goes smoothly. The Bone Health and Osteoporosis Foundation notes that a bone density scan generally doesn’t require you to undress, as long as you wear clothes without metal.
Recent contrast, barium or nuclear medicine exams
This is the most common reason a DEXA appointment gets rescheduled. If you recently had a barium study, or a CT or nuclear scan that used an injected contrast material, RadiologyInfo.org says you may need to wait 10 to 14 days before your DXA scan. The materials can interfere with image quality and with the density reading.
If you are scheduling several medical exams close together, book the DEXA scan first or leave enough of a gap. When you call, mention any contrast exam from the past two weeks. Some facilities ask for a window of a few days, others for longer, so let them tell you what applies.
Pregnancy
If there is any possibility you are pregnant, tell your healthcare provider and the technologist before the scan. The CDC explains that a DEXA scan uses a low dose of ionizing radiation and that scans are not recommended during pregnancy. Radiation from a DEXA scan is very low, but the precaution is there for the developing fetus. If you are unsure, ask your doctor whether to postpone.
Tell the technologist about your spine and joints
Bone density in the lumbar spine can be hard to read when the spine itself has changed. Mayo Clinic notes that conditions such as spinal arthritis, scoliosis or previous spinal surgery can affect results. Mention any of these before the scan. The technologist can then position you properly, and your clinician can interpret the numbers with that context or suggest another site or method.
If you have already had a result that looked odd, our guide to when a spine T-score is misleading explains why it happens and what the next steps look like. The hip often gives a cleaner picture, and we explain why in our hip T-score article.
A day-before checklist
- Read the instructions sent by the facility, including any calcium window.
- Confirm there has been no barium or contrast exam in the recent past, and no pregnancy.
- Skip calcium supplements and calcium-containing multivitamins as instructed.
- Lay out loose clothes without metal.
- Bring your insurance card, your photo ID and the doctor’s order if one was issued.
- Write down your medications, past fractures, height loss and any spine surgery.
- If you have had a previous DEXA scan, bring the report or request that the facility pull it.
Cost is a common question at this point. Our overview of what a DEXA scan costs with or without insurance walks through the typical scenarios.
What happens during the scan
You check in, remove metal items, and lie on your back on the table. The technologist positions your legs and spine so the hip and lower spine can be imaged. A scanning arm passes above you. You are asked to stay still, and you shouldn’t feel anything. Cleveland Clinic describes it as an outpatient procedure with no needles or injections.
When it is done, you can usually go back to normal activities. You can restart your supplements unless you were told otherwise.
Choosing where to have the scan
Where you have it matters almost as much as how you prepare. The Bone Health and Osteoporosis Foundation recommends a facility whose staff are trained and certified, for example by the International Society for Clinical Densitometry, because accurate imaging and interpretation matter when you track bone health over time.
Two practical tips:
- Use the same facility and machine for follow-up scans when you can. Comparing numbers from different machines is less reliable than comparing numbers from the same one. Our article on DEXA scan accuracy covers this in more detail.
- Ask who interprets the report. You want a clinician who also looks at your fracture history and other risk factors, not just a number.
Making sense of your results
Results come as a T-score and, for some people, a Z-score. Bone density results fall into three groups: normal, low density (osteopenia) and osteoporosis, according to the Bone Health and Osteoporosis Foundation. The same foundation stresses that a DXA scan doesn’t tell the whole story of bone strength. Fracture history and lifestyle factors matter just as much in deciding whether you need treatment.
If you want help reading your report, start with DEXA scan results explained. If your score sits between normal and osteoporosis, osteopenia versus osteoporosis explains what the range means in practice.
Our perspective: the scan is the start, not the plan
Most people who come to us arrive with a DEXA report in hand and a lot of questions. We see the same pattern again and again: people spend days worrying about the scan itself and very little time deciding what to do with the number afterward.
Our view is simple. Preparing well gets you a clean, comparable baseline. What you do after that decides whether the next scan looks any different. We work with people who have osteopenia or osteoporosis on a non-pharmaceutical protocol: osteogenic loading, one brief supervised session a week, at our centers in Rancho Cordova, El Dorado Hills and Granite Bay. We ask clients to bring their DEXA reports so we can see their starting point and track progress against it.
We also encourage people to keep their medical team in the loop. A bone density scan is a diagnostic tool. Decisions about medication belong with your doctor. What we add is a structured, supervised way to load your bones between scans. If you want to know whether that fits your situation, our write-up on whether your T-score can improve lays out what the evidence supports.
— Aaron
If you want to act on your results
If your scan shows low bone density and you’d like to talk through a supervised, weekly approach alongside your doctor’s care, you can learn about osteogenic loading at OsteoStrong. Our sessions are brief and supervised, and we offer them in Rancho Cordova, El Dorado Hills and Granite Bay. For the research behind the approach, see what the evidence says about osteogenic loading.
FAQ
What are you not supposed to do before a DEXA scan?
Don’t take calcium supplements for at least 24 hours, and don’t wear clothes or jewelry with metal. Don’t schedule the scan right after a barium or contrast exam, because you may need to wait 10 to 14 days. Tell staff if you might be pregnant.
Do I need an empty stomach for a DEXA scan?
No, not usually. You can generally eat and drink normally unless your provider says otherwise. If you have other tests booked the same day, check whether those require fasting.
What can throw off a DEXA scan?
Unabsorbed calcium supplements, metal in the scan area, and leftover contrast material can all affect the image. Spine changes such as severe arthritis, scoliosis or past surgery can also distort lumbar readings. Telling the technologist about each one lets them position you well and interpret the scan with care.
What should I wear to a DEXA scan?
Loose, comfortable clothes with no metal zippers, buttons, buckles or underwire. Leave jewelry at home. Some facilities may ask you to change into a gown.
Sources
- Bone Density Scan (DEXA or DXA), RadiologyInfo.org
- Bone density test (DXA/DEXA scan), Mayo Clinic
- Facts About Bone Density (DEXA Scan), CDC
- DXA Scan (Bone Density Test), Cleveland Clinic
- Bone Density Test, Osteoporosis Screening and T-score Interpretation, Bone Health and Osteoporosis Foundation
- Safe Movement, Bone Health and Osteoporosis Foundation