A bone density test, formally known as Dual-energy X-ray Absorptiometry (DXA), is a quick, non-invasive procedure used to measure bone mineral density. This scan is the standard method for diagnosing osteoporosis and assessing fracture risk, typically focusing on the hip and spine. The test uses a very low dose of X-rays to determine the density and mineral content of your bones. Proper preparation is important to ensure accurate results.
The Impact of Skin Products on Testing
Standard moisturizing lotions and creams generally do not interfere with the X-ray technology used in a DXA scan and are usually safe to wear. DXA X-rays measure the density of deep bone tissue, and most topical skin products are not dense enough to block or distort this signal. However, some facilities advise avoiding all topical products on the day of the scan to eliminate potential variables.
The primary concern involves skin products containing heavy metals or other dense, metallic compounds. Certain medicinal ointments, glittery body powders, or sunscreens containing zinc oxide or titanium dioxide can create artifacts on the scan image. These dense substances absorb the X-rays and appear as bright spots, potentially skewing the bone mineral density readings. If you are uncertain about a product’s ingredients, the safest approach is to skip its application to the areas being scanned.
Essential Preparation Guidelines
While standard lotions are typically not an issue, other items can significantly compromise the accuracy of a DXA test. Since the scan uses X-rays, any material denser than soft tissue in the path of the beam can distort the reading. Therefore, removing all metal objects from the area being scanned is a strict requirement.
This includes all jewelry, metal zippers, buttons, buckles, and underwire bras that might cover the spine or hip. Metal is highly dense and absorbs the X-rays, causing an artificially high density reading that can mask true bone loss. Wearing comfortable, loose clothing without metal components is advised, or you may be asked to change into a metal-free gown.
Additionally, you should pause certain oral supplements for at least 24 hours before the test. Calcium supplements and multivitamins containing calcium must be avoided. Undigested residue in the gastrointestinal tract can temporarily inflate the density reading if it is within the scan field.
Understanding the DXA Test Process
The DXA scan is a straightforward, outpatient procedure that takes about 10 to 20 minutes to complete. During the test, you will lie flat on a padded table, usually on your back. A technologist will help position your body, sometimes using foam blocks to ensure the correct alignment of the hips and spine.
A mechanical scanning arm will slowly pass over the body part being measured, emitting a very low dose of X-rays. The radiation exposure is minimal, significantly less than a standard chest X-ray. You must remain very still during the scan for the images to be clear and accurate. The procedure is painless, requires no injections, and allows you to resume normal activities immediately afterward.