What measurement indicates a diagnosis of osteoporosis according to WHO criteria?

• A. 1.0 SD or more below the young adult peak bone density
• B. 2.0 SD or more below the young adult peak bone density
• C. 2.5 SD or more below the young adult peak bone density
• D. 3.0 SD or more below the young adult peak bone density

Answer: (C)

The diagnosis of osteoporosis is established by the World Health Organization (WHO) criteria, which specifies that a bone mineral density (BMD) measurement of 2.5 standard deviations (SD) or more below the young adult peak bone density is indicative of osteoporosis. This threshold helps categorize the degree of bone loss in relation to peak bone mass achieved in a healthy young adult population.

Bone densitometry is primarily utilized to assess an individual's risk of fractures and to evaluate their bone health. The measurement of bone density compared to a reference population allows healthcare providers to assign a T-score, which signifies how much lower an individual's bone density is relative to that of a healthy young adult. When a patient's T-score indicates a difference of 2.5 SDs or more, it signifies a significant decrease in bone density, thus enhancing their risk of fractures due to osteoporosis.

Understanding this criterion is crucial since it provides a clear demarcation for clinical diagnosis and guides management strategies for patients identified as being at risk for skeletal-related events. The focus on an SD of 2.5 underlines the importance of specific metrics in identifying osteoporosis and tailoring appropriate treatment protocols for prevention and management.