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The sex hormones oestrogen and testosterone play a vital role in the development and maintenance of the skeleton.
During puberty the increased levels of the sex hormones lead to an increase in the size of bones as well as bone mass. Sustained production of oestrogen is vital in adolescent females and young women so as to maintain bone mass.
Reduced exposure to oestrogen during life as can occur when there are absent or infrequent menstrual cycles, delay in the onset of the first period, strenuous athletic training, low body weight or an early menopause will affect the attainment of peak bone mass in adolescence and early adulthood and also the maintenance of bone mass in latter life.2,56
Menopause is associated with a dramatic fall in oestrogen levels, that results in significant loss of bone mass which can last from 4 to 8 years after the onset of menopause.4 This bone loss mainly affects trabecular bone, which is normally highly responsive to the effects of oestrogen.4 Hence postmenopausal bone loss primarily effects vertebral bone mass integrity due to the high proportion of trabecular bone. Even in the years immediately preceding menopause there can be a drop in oestrogen levels that leads to a fall in bone mineral density.9
In addition to oestrogen, androgens also play a vital role in the integrity of the female skeleton. Low androgen levels in the premenopausal years, have been found to also correlate with low bone density.10 In the peri- and postmenopausal years both low oestrogen and testosterone levels are associated with a reduced bone mass.10
Women in the immediate menopausal years, usually in the first 3 years, can expect to lose bone at a rate of approximately 2% per year especially in the spine.17,18 The loss of bone at other sites is either similar or less.2,17 Once women have passed through this rapid rate of bone loss, the rate of bone loss significantly slows and women generally can expect to lose approximately less than 1% of bone density at the hip per year, with the rate of change in the spine being even slower.17,18
In addition to the effects of the sex hormones on the skeleton, growth hormone and IGF-1 also play an important role in skeletal growth and maintenance of the integrity of the skeleton.3,4,55
Content updated July 28, 2009
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