For women, the early
postmenopausal period is a time when they experience
an accelerated rate of bone loss, lasting 4 to 8 years, due
to an increase in osteoclastic activity and bone resorption
resulting from estrogen withdrawal (Fig. 29.1) [26]. The
loss after 5 to 10 years amounts to about 10% to 15% in
BMD or one standard deviation (SD), which can increase
the risk of fracture by 1.5- to 3-fold [27,28]. Subsequently,
the rate of bone loss in women declines to about 1% per
year, depending on site, which is related to both estrogen
deficiency and increases in parathyroid hormone
(PTH) due to decreasing intestinal absorption efficiency
and impaired osteoblast function