What is the World Health Organization (WHO) definition of osteoporosis?: (A) Bone mineral density less than 1 standard deviation below the mean of a young, healthy adult., (B) Bone mineral density at least 2.5 standard deviations below the mean of a young, healthy adult., (C) T score less than -2.5., (D) (B) and (C).
Answer is D. Ans. D. (B) and (C).In 1994, the WHO introduced definitions for osteoporosis and osteopenia in terms of T score thresholds of -2.5 and -1 respectively. A T score of -2.5 means that the bone mineral density in the lumbar spine (L2-L4) is at least 2.5 standard deviations below the mean of a young (age 25-35), healthy female. A T score of more than -2.5 implies it is more positive and hence could represent either osteopenia or normal bone density.