1. What is a T-Score?

The T-score compares an individual's bone mineral density (BMD) to that of a healthy young adult reference population. It is the standard deviation (SD) difference from the mean BMD of the reference group.

2. How Does the Calculator Work?

The calculator uses the T-score equation:

Where:

• \( BMD \) — Measured bone mineral density (g/cm²)
• \( \mu_{ref} \) — Mean BMD of young healthy reference population (g/cm²)
• \( \sigma_{ref} \) — Standard deviation of reference population (g/cm²)

Explanation: The T-score indicates how many standard deviations your BMD is above or below the average for a healthy young adult of your sex.

3. Clinical Significance of T-Score

Details: T-scores are used to diagnose osteoporosis and assess fracture risk:

• T-score ≥ -1.0: Normal bone density
• -1.0 > T-score > -2.5: Osteopenia (low bone mass)
• T-score ≤ -2.5: Osteoporosis

4. Using the Calculator

Tips: Enter your measured BMD in g/cm², the reference population mean (typically provided by the DEXA report), and the reference population standard deviation. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between T-score and Z-score?
A: T-score compares to young adults, while Z-score compares to age-matched peers. T-score is used for diagnosis in adults.

Q2: Where are T-scores typically measured?
A: Most commonly at the lumbar spine, total hip, or femoral neck.

Q3: How often should DEXA scans be repeated?
A: Generally every 1-2 years to monitor treatment or disease progression.

Q4: Can T-scores vary between machines?
A: Yes, slight variations exist between different DEXA machines. Follow-up scans should ideally use the same machine.

Q5: What factors can affect T-score accuracy?
A: Vertebral fractures, osteoarthritis, scoliosis, and metal implants can affect spine measurements.