Question

Define osteoporosis .explain various types with associate pathological changes

Answer 1

WHO definition of osteoporosis

Bone mineral density (BMD) in a patient is related to peak bone mass and, subsequently, bone loss. Whereas the T-score is the patient’s bone density compared with the BMD of control subjects who are at their peak BMD, the Z-score reflects a bone density compared with that of patients matched for age and sex. [5, 6, 7, 8]
The World Health Organization’s (WHO) definitions of osteoporosis based on BMD measurements in white women are summarized in Table 1, below. [7, 8] For each standard deviation (SD) reduction in BMD, the relative fracture risk is increased 1.5-3 times.

The WHO definition applies to postmenopausal women and men aged 50 years or older. Although these definitions are necessary to establish the prevalence of osteoporosis, they should not be used as the sole determinant of treatment decisions. This diagnostic classification should not be applied to premenopausal women, men younger than 50 years, or children.

Table 1. WHO Definition of Osteoporosis Based on BMD Measurements by DXA (Open Table in a new window)

DefinitionBone Mass Density MeasurementT-ScoreNormalBMD within 1 SD of the mean bone density for young adult womenT-score ≥ –1Low bone mass (osteopenia)BMD 1–2.5 SD below the mean for young-adult womenT-score between –1 and –2.5OsteoporosisBMD ≥2.5 SD below the normal mean for young-adult womenT-score ≤ –2.5Severe or “established” osteoporosisBMD ≥2.5 SD below the normal mean for young-adult women in a patient who has already experienced ≥1 fracturesT-score ≤ –2.5 (with fragility fracture[s])Sources: