Preparing for Your DEXA Scan: Key Areas to Address
Proper preparation is essential for a Dual-Energy X-ray Absorptiometry (DEXA) scan, whether it's for bone mineral density (BMD) or body composition analysis. The following sections detail the specific things you should avoid to ensure your results are consistent and reliable. Failing to follow these guidelines can lead to skewed measurements and potentially inaccurate diagnoses.
Medications and Supplements to Discontinue
Certain supplements and over-the-counter medications can interfere directly with the scan's accuracy. The most important substance to avoid is calcium, as its presence in the digestive system or bloodstream can give a false impression of higher bone density. The general recommendation is to stop taking these items at least 24 hours before your appointment. For optimal results, check with your healthcare provider for their specific instructions.
Calcium and Vitamin D
- Calcium Supplements: These are the most critical to avoid. Ingesting extra calcium shortly before the scan can artificially inflate your bone density measurements. This includes dedicated calcium supplements, as well as multivitamins containing calcium. The advised timeframe is at least 24 hours prior to your scan, though some facilities may recommend longer.
- Antacids: Many antacids, such as Tums and Rolaids, contain high levels of calcium carbonate. Treat these like calcium supplements and avoid them for the same duration.
- Multivitamins: Check the label on your multivitamin. If it contains calcium, you should skip it for a full day before your scan.
Other Considerations
- Prescription Medications: You should continue to take all other prescribed medications as directed unless your doctor explicitly tells you otherwise. If you are on a specific osteoporosis medication, your doctor will advise you on the correct protocol.
- Contrast Agents: If you have had any recent medical imaging tests involving contrast materials, such as a CT scan with injected contrast or a barium study, you must wait a specific period. Contrast agents can obscure or interfere with the DEXA scan results. The waiting period is often 7 days or more for barium studies and at least 3 days for injected contrast.
Dietary and Hydration Factors
While a DEXA scan for bone density doesn't typically require fasting, certain dietary habits can affect the accuracy of body composition measurements. Consistency is key, so if you are tracking body composition over time, you should aim to repeat your pre-scan routine precisely.
Food and Drink
- Large Meals: Avoid eating a large meal 2–3 hours before your scan, especially if you are having body composition measured. A full stomach can slightly alter readings.
- Caffeinated and Sugary Drinks: Caffeine and high-sugar drinks can impact hydration levels and metabolism. It is best to skip coffee, tea, and sugary sodas for at least 12–24 hours beforehand.
- Alcohol: Alcohol should be avoided for at least 24 hours before the scan, as it can cause dehydration and affect body composition measurements.
Hydration
- Overhydration: Drinking an excessive amount of water right before your appointment can temporarily increase your lean mass readings. While staying hydrated is healthy, it is best to stick to a moderate amount of water.
Lifestyle and Physical Activity
Your recent activity level can also influence the scan's outcome. Certain physical activities can cause temporary changes in muscle hydration that may affect readings.
- Intense Exercise: Avoid vigorous exercise or heavy weightlifting for at least 24 hours before your scan. This type of activity can increase water retention in your muscles, leading to inaccurate lean mass measurements.
- New Routines: If you've just started a new diet or exercise regimen, it's best to have your baseline DEXA scan before these changes fully take effect to get a true starting point.
What to Wear and Remove for Your Scan
Metal objects can significantly interfere with the DEXA machine's X-ray beams, creating artifacts on the image and rendering results inaccurate. You will be asked to remove all metallic items before the procedure.
- Metal Clothing: Wear loose-fitting, comfortable clothing that does not have metal zippers, belts, or buttons. In many cases, you will be asked to change into a gown provided by the clinic.
- Jewelry and Piercings: All jewelry, including earrings, necklaces, and body piercings below the neck, should be removed before the scan. Leaving these items on can create shadows and disrupt the scan's clarity.
- Other Metal Objects: Be sure to empty your pockets of any metal, such as keys or coins.
Other Pre-Scan Warnings
To ensure your safety and the accuracy of your scan, you should always inform the technologist of certain medical information.
- Pregnancy: You must inform your doctor and the technician if you are pregnant or think you might be. DEXA scans use a low dose of radiation, but it is not advised for pregnant individuals.
- Recent Surgical Procedures: If you have had any recent surgeries with implanted metal hardware, such as a hip replacement, the metal will affect readings in that specific area. The technician must be aware of this.
- Other Implants: Let your healthcare provider know if you have any other implants, such as breast implants or pacemakers, as these can also interfere with body composition results.
Comparison Table: Avoid vs. Acceptable
| Action/Item | |
|---|---|
| AVOID | ACCEPTABLE |
| Calcium Supplements (24 hrs prior) | Foods containing natural calcium (e.g., dairy) |
| Multivitamins with calcium (24 hrs prior) | All other prescribed medications |
| Contrast dye procedures (days/week prior) | Standard hydration |
| Metal clothing (zippers, buckles, buttons) | Loose, metal-free clothing |
| All jewelry & body piercings | |
| Intense exercise (24 hrs prior) | |
| Large meals (2-3 hrs prior) | Light meal 2-3 hours prior |
| Caffeine, alcohol, sugary drinks (12-24 hrs prior) |
The Importance of Accurate Baseline Data
Ensuring your DEXA scan is as accurate as possible helps establish a reliable baseline. This allows your doctor to make more informed decisions about your bone health or fitness journey, and to track changes accurately over time. Repeat scans are only useful if the initial data is sound. For more authoritative guidance on DEXA scan preparation, you can consult with resources like Johns Hopkins Medicine.
Conclusion
By following these straightforward preparation guidelines, you can help ensure your DEXA scan provides the most precise and reliable results. These steps, which include avoiding calcium supplements and recent contrast studies, wearing metal-free clothing, and being mindful of your diet and exercise, are simple yet critical for an accurate diagnosis or body composition assessment. Always communicate any relevant medical history with your healthcare provider and the imaging technologist to ensure a smooth and successful procedure.
