[Relationship between the age of menarche, menopause and other factors and postmenopause osteoporosis]

To evaluate the relationship between osteoporosis (OP) and the age of menarche and menopause, parity and lactation and bone mineral density (BMD).

BMD was measured in 1472 postmenopausal women by Norland XR-36 dual energy X-ray absorptiometry (DXA) from May 1999 to April 2003 in our hospital. All data of BMD were compared and statistically analyzed between women with different age of menarche and menopause, parity and lactation period. The diagnostic criteria of osteoporosis was defined by a loss of BMD greater than 2.5 standard deviations below average peak BMD of young adult women.

In all 1472 subjects, the incidence of osteoporosis is 58.5% (861/1472). There was significant increase in osteoporosis of lumbar spine in women with the age of menarche > or = 17 (119 out of 336 cases were with osteoporosis in lumbar) compared with women with age of menarche < or = 13 (75 out of 276 cases were with osteoporosis in lumbar). In women with menarche age of 11-13, 14-16, 17-19, lumbar vertebral (L(2-4)) BMD values were (0.83 +/- 0.16), (0.82 +/- 0.16), (0.80 +/- 0.14) g/cm(2), respectively. There was significant increase in BMD of lumbar in the menarche age group of 11-13 compared with the age group of 17-19 in women within menopause 1-10 years (P < 0.05). Among all women aged between 55-65, there was significant increase in OP in women with the menopause age < or = 48 compared with menopause age > or = 54 (P < 0.01). BMD of the L(2-4), Trochanter, Ward triangle was significantly increased in women who had had one delivery or being nulliparous compared with women having more than four deliveries; BMD of the L(2-4), Ward's triangle were significantly increased in women with less than six months of lactation compared with those lactating more than thirty-six months.

The later the menarche and the earlier the menopause, the higher the degree of osteoporosis; the more deliveries and period of lactation, the lower the BMD. Age is one of the high risk factors of osteoporosis.