Learn About Bone Density Testing and What Happens

What Bone Density Testing Is and Why It Matters

Bone density testing, also called a DXA scan or DEXA scan, is a medical imaging procedure that measures how dense your bones are. The scan uses very low levels of X-rays to take pictures of your bones, typically focusing on your hip, spine, and sometimes your forearm. The amount of mineral content in your bones determines their density—bones with higher mineral content are denser and generally stronger.

Your bones are living tissue that constantly breaks down and rebuilds throughout your life. When you're younger, new bone is made faster than old bone is removed, which increases your bone mass. Most people reach their peak bone mass around age 30. After that, bone remodeling continues, but you lose slightly more bone mass than you gain. This natural process becomes a concern when bones lose too much density and become fragile.

Bone density testing matters because it can reveal whether your bones are at risk of fracturing more easily than they should. A fracture from a minor fall or even a cough can indicate weak bones. Hip fractures often require surgery and can lead to long-term disability. Spine fractures may not cause immediate pain but can result in lost height, stooped posture, and chronic discomfort. Wrist fractures are also common in people with low bone density.

The test produces a score that compares your bone density to that of a healthy young adult. This comparison helps doctors understand your bone health status and determine whether you need monitoring, lifestyle changes, or medical treatment. Understanding your bone density results gives you information to make decisions about your health moving forward.

Practical takeaway: Bone density testing provides objective measurement of your skeletal strength. Knowing your bone density status allows you to understand your fracture risk and explore options for maintaining or improving bone health.

Who Should Consider Bone Density Testing

Bone density testing recommendations vary based on age, sex, and risk factors. The U.S. Preventive Services Task Force recommends that all women age 65 and older have bone density screening. For men, routine screening is generally recommended starting at age 70, though some organizations suggest age 50 for men at higher risk. However, younger people with specific risk factors may also benefit from testing.

Certain medical conditions increase fracture risk regardless of age. People with rheumatoid arthritis, type 1 diabetes, celiac disease, kidney disease, or liver disease often have lower bone density. Additionally, anyone who takes corticosteroid medications for more than three months should have their bones monitored, as these drugs can weaken bone density. Thyroid disease, especially if undertreated, also affects bone health.

Hormonal changes significantly impact bone density. Women entering or in menopause experience rapid bone loss due to declining estrogen levels. Men with low testosterone levels may also experience accelerated bone loss. A personal history of fractures, particularly from minor trauma, suggests the need for testing. Family history matters too—if a parent or sibling had a hip fracture or osteoporosis, your risk is elevated.

Lifestyle factors influence bone density as well. People who smoke, drink heavily, get little physical activity, or consume inadequate calcium and vitamin D have weaker bones. Being underweight or having a small frame also increases fracture risk. Certain medications beyond corticosteroids, including some cancer treatments and medications for seizures, can affect bone density.

Practical takeaway: Consider whether you fall into a higher-risk category based on age, sex, medical history, medications, or lifestyle factors. Discussing your personal risk profile with a healthcare provider helps determine whether bone density testing would provide useful information about your skeletal health.

How the Bone Density Test Works

The bone density scan is a straightforward outpatient procedure that takes about 10 to 30 minutes. You'll be asked to lie still on a padded examination table while a mechanical arm passes over your body, taking X-ray images. The arm moves slowly across your hip, spine, and sometimes your forearm. You don't need to undress completely—you'll wear comfortable clothing without metal buttons, zippers, or fasteners. Jewelry and metal objects must be removed from the scanning area.

The DXA scanner uses two different X-ray beams at different energy levels to measure bone density more accurately than standard X-rays. The machine calculates the ratio of bone mineral content to the area of bone scanned. A computer then compares your results to reference standards. The radiation exposure from a DXA scan is extremely low—roughly equivalent to the radiation you receive from a few hours of natural background exposure in your environment. It's much lower than a standard chest X-ray.

During the scan, you must remain still to ensure clear images. Some facilities may use positioning aids or straps to help you stay in place. You may hear quiet humming or beeping sounds as the scanner operates. The procedure is painless—there are no injections, no contrast dye, and nothing inserted into your body. You won't feel anything during the scan itself.

Different facilities may scan slightly different bone sites depending on their equipment and your medical history. The standard sites are the lumbar spine (lower back) and hip, as these are common fracture locations and show changes in bone density most clearly. Some tests also include the forearm. Your healthcare provider determines which sites need scanning based on your individual situation.

Practical takeaway: Bone density testing is a quick, painless procedure with minimal radiation exposure. Understanding what to expect during the scan helps you prepare and know what to bring—typically just your insurance information and a list of medications and supplements you take.

Understanding Your Bone Density Test Results

Bone density results are reported using a T-score, which compares your bone density to that of a healthy 30-year-old adult of the same sex. The T-score is expressed as a number of standard deviations above or below the average. A T-score of -1.0 or higher is considered normal bone density. A T-score between -1.0 and -2.5 indicates low bone density, a condition called osteopenia. A T-score of -2.5 or lower indicates osteoporosis, a more serious weakening of bone structure.

To put numbers in perspective, studies show that each decrease of one standard deviation in bone density roughly doubles your fracture risk. For example, if your T-score is -2.5, your bones are significantly weaker than normal, and your risk of fracture over the next 10 years is substantially higher than someone with normal bone density. However, a low T-score doesn't mean a fracture will definitely occur—it indicates increased risk.

Results may also include a Z-score, which compares your bone density to other people of your same age, sex, and body size. A Z-score below -2.0 suggests bone loss greater than expected for your age and may indicate an underlying medical condition worth investigating further. Healthcare providers use both T-scores and Z-scores together with your medical history to assess your fracture risk more completely.

Your results report typically shows bone density at each scanned site. Some areas may show normal density while others show lower density. For example, your spine might show osteoporosis while your hip shows osteopenia. Your healthcare provider interprets these differences in context. Osteoporosis at the hip generally carries higher fracture risk than osteoporosis at the spine alone. Follow-up testing locations depend on where problems were found.

Practical takeaway: Review your results report carefully and ask your healthcare provider to explain what your T-score and Z-score mean for your individual situation. Understanding these numbers helps you grasp your bone health status and what steps might help manage your skeletal strength going forward.

Steps to Take After Receiving Your Results

If your test shows normal bone density, continue the habits that support strong bones. This means getting adequate calcium through diet or supplements, maintaining sufficient vitamin D through sun exposure or supplements, staying physically active with weight-bearing exercise, avoiding smoking, and limiting alcohol consumption. Most healthcare providers recommend repeat testing every 1 to 2 years for ongoing monitoring, though intervals may be longer if your bones remain stable.

If your results show low bone density, several approaches can slow further loss and potentially improve density. Calcium intake should reach 1,000 to 1,200 mg daily through foods like dairy products, leafy greens, fortified plant-based beverages, and almonds. Vitamin D,