A Population-Based Assessment of Rates of Bone Loss at Multiple Skeletal Sites: Evidence for Substantial Trabecular Bone Loss in Young Adult Women and Men

Abstract

Using QCT, we made a longitudinal, population-based assessment of rates of bone loss over life at the distal radius, distal tibia, and lumbar spine. Cortical bone loss began in perimenopause in women and later in life in men. In contrast, trabecular bone loss began in young adulthood in both sexes.Introduction: Although conventional wisdom holds that bone loss begins at menopause in women and later in life in men, this has not been examined longitudinally in population-based studies using precise technology capable of distinguishing cortical and trabecular bone. Materials and Methods:In an age-and sex-stratified population sample (n ‫ס‬ 553), we measured volumetric BMD (vBMD) of trabecular and cortical bone by QCT annually for up to 3 yr at the distal radius (DR) and distal tibia (DT) (n ‫ס‬ 552) and trabecular vBMD at baseline and 3 yr at the lumbar spine (LS) (n ‫ס‬ 474). Results: Substantial cortical bone loss began in middle life in women but began mainly after age 75 in men. In contrast, substantial trabecular bone loss began in young adult women and men at all three skeletal sites and continued throughout life with acceleration during perimenopause in women. Women experienced 37% and men experienced 42% of their total lifetime trabecular bone loss before age 50 compared with 6% and 15%, respectively, for cortical bone. Median rates of change in trabecular bone (%/yr) were −0.40, −0.24, and −1.61 in young adult women and −0.38, −0.40, and −0.84 in young adult men at the DR, DT, and LS, respectively (all p < 0.001). The early trabecular bone loss did not consistently correlate with putative causal factors, except for a trend with IGF-related variables at DT in women. However, in postmenopausal women and, to a lesser extent, in older men, higher rates of cortical and trabecular bone loss were associated with lower levels of biologically-active sex steroids and with higher levels of follicle-stimulating hormone and bone turnover markers. Conclusions:The late onset of cortical bone loss is temporally associated with sex steroid deficiency. However, the early-onset, substantial trabecular bone loss in both sexes during sex steroid sufficiency is unexplained and indicates that current paradigms on the pathogenesis of osteoporosis are incomplete.

Application of quantitative computed tomography for assessment of trabecular bone mineral density, microarchitecture and mechanical property

“…Whole-body spiral CT scan allow densitometric evaluations of the distal radius, tibia and other sites with good accuracy (R values 0.55-0.8 between QCT and DXA) [8,77,78]. A lower annual bone loss rate was found when compared to the central bone [76]. This method also provides a tool to further investigate cortical and trabecular bone microstructures.…”

“…The QCT technique has also been used for the peripheral BMD measurement using the spiral CT scan of upper [76,77] or lower extremity bone [8,76,78]. Whole-body spiral CT scan allow densitometric evaluations of the distal radius, tibia and other sites with good accuracy (R values 0.55-0.8 between QCT and DXA) [8,77,78].…”

“…The result indicated that the annual loss rate of the lumbar spine is 2-6 folds to that of the peripheral sites at distal radius and tibia with a trabecular QCT measurement [76]. Studies indicated that the trabecular QCT of spinal bone displayed a strong capability for assessment of the bone loss rate and for discrimination of osteoporotic vertebral fractures.…”

“…Studies indicated that the trabecular QCT of spinal bone displayed a strong capability for assessment of the bone loss rate and for discrimination of osteoporotic vertebral fractures. In comparison to the central bone, the peripheral bone had the weakest capability for these applications [7,76,95].…”

“…There was a strong variation in the bone annual loss rate in the study cohort with different age and clinical implications. Overall, the trabecular bone has a 3-10 fold bone loss rate compared to the cortical bone [76,95,[97][98][99].…”