Bone Density Testing — Advanced Densitometry and Micro-architecture
While Bone Mineral Density (BMD) is the primary metric for diagnosing osteoporosis, 2026 clinical standards emphasize that density is not the same as quality.
DXA Analysis: Dual-Energy X-ray Absorptiometry (DXA) measures the attenuation of two X-ray beams as they pass through bone. Results are expressed as T-scores (comparison to a young adult) and Z-scores (comparison to age-matched peers).
TBS (Trabecular Bone Score): This is a software-based tool applied to the DXA image. It evaluates the "pitting" or "texture" of the bone. A high TBS indicates a strong, well-connected micro-architecture, while a low TBS indicates "brittle" bone, even if the density (BMD) appears normal.
Clinical Thresholds: Osteoporosis is defined as a T-score of $\le -2.5$. However, the 2026 FRAX (Fracture Risk Assessment Tool) now integrates TBS data to provide a more accurate 10-year probability of a major osteoporotic fracture.
