According to the WHO, what is the definition of osteoporosis?

• A. T-score more than 2.5 SD
• B. T-score less than -1 SD
• C. T-score less than -2.5 SD
• D. T-score equal to 0 SD

Answer: (C)

The definition of osteoporosis, as specified by the World Health Organization (WHO), is characterized by a T-score of less than -2.5 standard deviations (SD) from the mean bone mineral density (BMD) of a healthy young adult population. This threshold indicates a significant reduction in bone density, which correlates with an increased risk of fractures.

The T-score is a critical measurement derived from dual-energy X-ray absorptiometry (DXA) scans, serving as an essential criterion in diagnosing osteoporosis. A T-score below -2.5 SD signifies that the individual’s bone density is substantially lower than that of a healthy reference group, thus implicating a condition where bone strength and integrity are compromised.

In addition, understanding the context of the other choices is important to be able to apply this knowledge in practical scenarios. For instance, a T-score greater than -1 SD, as indicated in one of the incorrect options, denotes normal bone density, whereas a T-score between -1 and -2.5 SD is classified as low bone mass or osteopenia, rather than osteoporosis. Consequently, a T-score that is equal to 0 SD reflects normal bone density, hence not meeting the criteria for osteoporosis.

Familiarity with these