What is the scan called to check for osteoporosis?

According to the Bone Health and Osteoporosis Foundation, roughly 10 million Americans have osteoporosis, a condition that weakens bones and increases fracture risk. The most common and accurate method for diagnosing this disease and assessing bone density is a specialized, low-dose X-ray. Understanding what is the scan called to check for osteoporosis is a vital first step towards proactive bone health and prevention.

Quick Summary

The scan used to check for osteoporosis is called a dual-energy X-ray absorptiometry, most often referred to as a DEXA or DXA scan, which is the standard for measuring bone mineral density.

Key Points

• Scan Name: The standard scan to check for osteoporosis is called a dual-energy X-ray absorptiometry, or DEXA (sometimes DXA) scan.

• Purpose: The DEXA scan measures bone mineral density (BMD) to diagnose osteoporosis, identify low bone mass (osteopenia), and predict fracture risk.

• Key Scores: Results are primarily reported as a T-score, which compares your bone density to that of a healthy young adult, and a Z-score, which compares it to people of your age group.

• Simple Procedure: The scan is quick, painless, and uses a very low dose of radiation, similar to a standard X-ray.

• Who Needs It: Screening is typically recommended for women over 65 and men over 70, or for younger adults with specific risk factors like a family history of osteoporosis or certain medical conditions.

• Central vs. Peripheral: The central DEXA scan of the hip and spine is the standard for diagnosis, while peripheral scans of the wrist or heel are used for preliminary screening.

• Early Detection is Key: Identifying low bone density early allows for treatment and lifestyle changes that can prevent future fractures and manage the condition effectively.

What is a DEXA Scan?

A DEXA (Dual-Energy X-ray Absorptiometry) scan is a non-invasive imaging test that measures bone mineral density (BMD). The scan uses a very low dose of X-rays to assess the amount of calcium and other minerals packed into a specific segment of bone, typically in the hip and spine. The resulting images and data are used by healthcare professionals to diagnose osteoporosis, determine a person's risk for future fractures, and monitor the effectiveness of treatment over time. This quick, painless procedure provides a clearer picture of bone strength than a standard X-ray alone, which can only detect osteoporosis in more advanced stages.

Who Should Get a Bone Density Scan?

Medical guidelines recommend bone density screening for specific populations, but a doctor may suggest a DEXA scan for anyone with risk factors.

General Screening Guidelines

• Women: All women aged 65 or older should be screened. Postmenopausal women younger than 65 may need screening if they have risk factors.
• Men: All men aged 70 or older should be screened, with some guidelines suggesting earlier screening for men aged 50-69 with risk factors.

Other Risk Factors for Earlier Screening

• A fragility fracture, which is a break from a fall at or below standing height.
• A family history of osteoporosis, particularly a history of hip fractures in a parent.
• Long-term use of certain medications, such as corticosteroids.
• Low body weight or a slender frame.
• Medical conditions such as rheumatoid arthritis, kidney disease, or an eating disorder.
• Significant height loss (more than 1.5 inches for women, 2 inches for men).
• Lifestyle factors like smoking and excessive alcohol intake.

What to Expect During the DEXA Procedure

A DEXA scan is a simple outpatient procedure that is generally quick and painless.

1. Preparation: You may be asked to avoid taking calcium supplements for 24-48 hours before the exam. Wear loose, comfortable clothing without metal fasteners, zippers, or buttons.
2. During the Scan: You will lie flat on a padded table. The technician may position your legs using a foam block to get the best images of your hip and spine. A scanning arm will then pass over your body. You will be asked to remain very still and may be asked to hold your breath for a few seconds to prevent motion blur.
3. Duration: The entire process usually takes about 10 to 30 minutes, depending on the number of sites being scanned.
4. After the Scan: There are no side effects from the scan, and you can resume normal activities immediately afterward.

Understanding DEXA Scan Results: T-Scores and Z-Scores

Your bone density scan results will be presented in a report that includes a T-score and, in some cases, a Z-score.

The T-Score: This score compares your bone density to that of a healthy young adult of the same sex at their peak bone mass.

• Normal: A T-score of -1.0 or higher. This indicates healthy bone density.
• Osteopenia: A T-score between -1.0 and -2.5. This indicates low bone mass and a higher-than-average risk for developing osteoporosis.
• Osteoporosis: A T-score of -2.5 or lower. This is the official diagnosis for osteoporosis.

The Z-Score: This score compares your bone density to that of other people in your same age group, sex, and ethnicity. If your Z-score is unusually high or low (typically -2.0 or lower), it might suggest that a medical condition or other factors are contributing to bone loss, requiring further investigation.

Types of Bone Density Scans: A Comparison

Different devices can measure bone density, but the central DEXA is the standard for diagnosis.

Feature	Central DEXA (Most Common)	Peripheral DEXA (p-DEXA)
Measurement Site	Hips, spine, and sometimes forearm.	Wrist, finger, ankle, or heel.
Primary Use	Standard for diagnosing osteoporosis, monitoring treatment, and assessing fracture risk.	Screening tool to help identify potential low bone mass.
Accuracy	Considered the most accurate method.	Less accurate than central DEXA for full diagnosis.
Location	Hospitals and imaging centers.	Doctor's offices or health fairs.
Details	Provides a comprehensive overview of bone density in critical areas.	Less detailed, and abnormal results often require a follow-up central DEXA.

The Importance of Early Diagnosis and Management

Early detection of low bone mass or osteoporosis is crucial. Because osteoporosis is often called a “silent disease,” many people don't know they have it until they suffer a fracture. By identifying bone loss early, you can work with your healthcare provider to create a plan that may include lifestyle changes, exercise, and medication to slow bone loss, improve bone strength, and significantly reduce your risk of fractures. An important first step for many is understanding the basics, and the Bone Health and Osteoporosis Foundation offers valuable resources and information for patients seeking to improve their bone health.

Frequently Asked Questions

What is the scan called to check for osteoporosis?

The most common and accurate scan used to check for osteoporosis is the dual-energy X-ray absorptiometry, which is abbreviated as DEXA or DXA.

Is the DEXA scan for osteoporosis painful?

No, a DEXA scan is a quick, non-invasive, and completely painless procedure. You simply lie on a padded table while a scanner arm passes over your body.

What does a bone density scan measure?

A bone density scan measures your bone mineral density (BMD). It assesses the amount of calcium and other minerals in your bones to determine their strength and thickness, primarily in the hip and spine.

Who should have a scan to check for osteoporosis?

Screening is generally recommended for all women aged 65 and older and men aged 70 and older. It may also be recommended for younger individuals with risk factors, such as a prior fracture or certain medical conditions.

How should I prepare for a DEXA scan?

To prepare for a DEXA scan, you should stop taking calcium supplements 24 to 48 hours beforehand. You should also wear loose, comfortable clothing and avoid any garments with metal buttons, buckles, or zippers.

What is a normal result on a bone density scan?

A normal result is defined by a T-score of -1.0 or higher. A score between -1.0 and -2.5 indicates low bone mass (osteopenia), and a score of -2.5 or lower indicates osteoporosis.

What is the difference between a DEXA scan and a regular X-ray?

While both use X-rays, a standard X-ray produces a picture of your bones and can only detect advanced osteoporosis. A DEXA scan, however, specifically measures bone density and provides a quantitative score to diagnose the condition earlier.

What if my bone density is low but not osteoporosis?

If your T-score indicates osteopenia, it means you have low bone mass. Your doctor will likely recommend lifestyle changes like increased weight-bearing exercise and dietary adjustments, and may suggest medications to prevent further bone loss.