Preparing for a Bone Health Screening: Tips for Accurate DEXA and Ultrasound Results

Bone health screenings such as dual‑energy X‑ray absorptiometry (DEXA) and quantitative ultrasound (QUS) are among the most reliable ways to assess skeletal strength and fracture risk. Because the numbers generated by these devices are highly sensitive to a variety of external factors, proper preparation can make the difference between a truly representative measurement and a misleading one. Below is a comprehensive, step‑by‑step guide to help you arrive at your appointment ready, relaxed, and confident that the results will reflect your bone health as accurately as possible.

Understanding the Two Common Tests (Brief Overview)

Both DEXA and QUS are non‑invasive, low‑radiation techniques, but they operate on different physical principles:

• DEXA uses two X‑ray beams at different energy levels to calculate bone mineral density (BMD) in the lumbar spine, hip, and sometimes the forearm. The machine measures the attenuation of each beam as it passes through bone and soft tissue, then computes an areal density (g/cm²).

• Quantitative Ultrasound sends high‑frequency sound waves through peripheral sites such as the calcaneus (heel bone) or the tibia. The device records the speed of sound (SOS) and broadband ultrasound attenuation (BUA), which together provide an index of bone quality that reflects both density and micro‑architectural properties.

Because each modality relies on precise interaction between the instrument and the patient’s body, any variable that alters tissue composition, positioning, or the acoustic/attenuation environment can skew the measurement. The preparation tips that follow are designed to control those variables.

Scheduling Your Appointment Wisely

1. Avoid the First or Last Slot of the Day – Early‑morning appointments may catch the machine before it has completed its daily warm‑up and calibration routine; late‑day slots can suffer from temperature fluctuations that affect ultrasound transducer performance. Mid‑morning or early afternoon times are generally the most stable.

2. Coordinate with Your Primary Care Provider – If you are on a medication that can acutely affect bone turnover (e.g., high‑dose steroids, bisphosphonates, or hormone therapy), ask whether a short “wash‑out” period is advisable. Your physician can help you schedule the scan at a point when the medication’s acute effects are minimized without compromising your treatment plan.

3. Allow Sufficient Time for the Scan – DEXA typically takes 10–20 minutes, while QUS may be completed in 5–10 minutes. However, the facility may need extra time for positioning, equipment checks, and answering any questions you have. Booking a 30‑minute window reduces the pressure to rush and helps you stay relaxed.

Reviewing Medications and Supplements

Certain drugs and supplements can temporarily alter the density of soft tissue or the acoustic properties of bone, leading to measurement artifacts:

Action Steps

• Compile a complete medication list, including over‑the‑counter supplements, and bring it to the appointment.
• Discuss with your prescriber whether any agents should be paused 24–48 hours before the scan (e.g., calcium antacids).
• If you are on a bisphosphonate, take the dose with a full glass of water and remain upright for at least 30 minutes afterward to avoid esophageal irritation that could cause discomfort during positioning.

Managing Calcium and Vitamin D Intake Before the Test

While calcium and vitamin D are essential for bone health, their recent ingestion can affect the soft‑tissue composition of the abdomen and lumbar region, which DEXA uses as a reference for attenuation correction.

• Avoid Calcium‑Rich Meals or Supplements Within 4 Hours – A large dairy meal or calcium tablet can increase the density of the gastrointestinal tract, leading to a slight overestimation of lumbar spine BMD.
• Maintain Consistent Vitamin D Levels – Sudden spikes in serum vitamin D are unlikely to affect the scan directly, but maintaining a stable intake (e.g., your usual daily dose) helps keep overall bone metabolism steady.

If you are unsure about timing, a simple rule is to have a light, low‑calcium snack (e.g., fruit) and postpone any calcium supplement until after the appointment.

Clothing and Personal Items: What to Wear and What to Remove

1. Choose Form‑Fitting, Metal‑Free Attire – Tight‑fitting shirts, leggings, or sports bras minimize the amount of soft tissue that the X‑ray must pass through and reduce the chance of metal artifacts. Avoid clothing with zippers, buttons, or underwire bras.

2. Remove All Metal Objects – This includes jewelry (necklaces, earrings, watches), belts, hairpins, and even metal‑backed eyeglasses. Even small metal pieces can create streak artifacts on DEXA images, especially in the lumbar region.

3. Footwear for QUS – If the ultrasound device scans the calcaneus, you will be asked to sit or lie down with the foot exposed. Remove socks, shoes, and any orthotic inserts.

4. Avoid Perfume or Lotions – Some topical products contain metallic particles that can interfere with the ultrasound transducer’s coupling gel. A clean, dry skin surface ensures optimal acoustic contact.

Timing of Physical Activity and Recent Injuries

• Refrain from Strenuous Exercise 24 Hours Prior – High‑impact activities (running, weightlifting) can cause temporary fluid shifts and micro‑trauma in the bone, potentially altering the acoustic properties measured by QUS.

• Report Any Recent Fractures or Sprains – Even a minor ankle sprain can lead to swelling that changes the soft‑tissue thickness around the scanning site, especially for heel ultrasound. The technologist may need to adjust positioning or postpone the scan if significant edema is present.

• Avoid Heavy Lifting on the Day of the Scan – Lifting heavy objects can compress the spine and pelvis, temporarily changing vertebral spacing and potentially affecting DEXA measurements of the lumbar spine.

Hydration and Fasting Guidelines

• Stay Well‑Hydrated – Adequate hydration maintains consistent soft‑tissue density, which is particularly important for DEXA’s attenuation correction algorithms. Aim for 8–10 oz of water in the hours before the appointment, but avoid excessive fluid intake that could cause abdominal distension.

• Fasting Is Not Required – Unlike some blood tests, a bone density scan does not require fasting. However, a light, low‑fat snack is advisable if you are prone to low blood sugar, especially if you will be lying still for several minutes.

Communicating Medical History and Prior Imaging

• Bring Prior Scan Reports – If you have had a DEXA or QUS performed previously, bring the printed or electronic reports. Even though the current article does not cover interpretation, having the prior data allows the technologist to compare positioning and ensure consistency.

• Disclose Surgical Implants or Hardware – Metal implants (hip replacements, spinal rods, dental crowns) can cause significant artifacts. While many modern DEXA machines can compensate for certain implants, informing the staff ahead of time enables them to select alternative scanning sites or adjust the analysis protocol.

• Mention Chronic Conditions – Conditions such as chronic kidney disease, hyperparathyroidism, or severe obesity can affect soft‑tissue composition and bone quality. The technologist may need to modify the scan parameters (e.g., using a higher‑energy beam for DEXA) to obtain reliable data.

Preparing the Testing Environment: What the Facility Does

Understanding the behind‑the‑scenes steps can reassure you that the equipment is calibrated for optimal performance:

1. Daily Quality Assurance (QA) Checks – Both DEXA and QUS devices undergo a series of phantom scans each morning to verify that the detector, X‑ray source, and ultrasound transducer are functioning within manufacturer‑specified tolerances.

2. Room Temperature and Humidity Control – Ultrasound speed is temperature‑dependent; a stable environment (≈ 22 °C, 40–60 % humidity) ensures consistent BUA and SOS readings.

3. Patient Positioning Protocols – Technologists follow standardized positioning guides (e.g., supine with legs extended for lumbar DEXA, foot secured in a neutral position for heel QUS). Consistency in positioning reduces variability between visits.

4. Use of Calibration Phantoms – For DEXA, a bone‑equivalent phantom is scanned periodically to adjust the software’s conversion factors. For QUS, a reference block with known acoustic properties is used to verify transducer performance.

If you have any concerns about these procedures, feel free to ask the staff to demonstrate the QA process or to show you the calibration phantom.

Reducing Anxiety and Staying Comfortable During the Scan

• Practice Deep Breathing – Slow, diaphragmatic breaths help you stay relaxed and minimize involuntary movements that could blur the image.

• Use a Pillow or Cushion – If you experience discomfort while lying flat (common for individuals with lower‑back pain), ask the technologist for a small pillow under the knees or lumbar region. This does not affect the scan as long as the area of interest remains unobstructed.

• Stay Still, Not Rigid – Slight, natural adjustments are acceptable, but avoid shifting the entire body. The technologist will give you a clear cue when to hold still for a few seconds.

• Ask About Noise Levels – DEXA machines emit a low‑level whirring sound; QUS may produce a faint clicking. Knowing that these noises are normal can prevent startle responses.

Post‑Test Follow‑Up: What to Do After the Results Arrive

While the focus of this guide is on preparation, a brief note on the next steps helps you close the loop:

• Request a Copy of the Raw Scan Images – Having the original DICOM files or ultrasound waveforms allows your physician to review the technical quality if needed.

• Schedule a Review Appointment – Arrange a follow‑up with the clinician who ordered the test to discuss the findings in the context of your overall health plan.

• Document Any Issues – If you experienced discomfort, positioning difficulties, or noticed artifacts (e.g., a visible metal object on the image), note these in your medical record. This information can be valuable for future scans.

Final Thoughts

Accurate bone health screening hinges on more than just the technology; it requires thoughtful preparation, clear communication, and a calm mindset. By managing medications, timing meals and activities, selecting appropriate attire, and understanding the technical safeguards employed by the imaging facility, you can help ensure that your DEXA or quantitative ultrasound results truly reflect the state of your skeleton. Armed with reliable data, you and your healthcare team will be better positioned to make informed decisions about bone health maintenance and any necessary interventions.