Nguyen T V, Jones G, Sambrook P N, White C P, Kelly P J, Eisman J A
Bone and Mineral Research Division, St. Vincent's Hospital, Sydney, New South Wales, Australia.
J Clin Endocrinol Metab. 1995 Sep;80(9):2709-14. doi: 10.1210/jcem.80.9.7673413.
The risk of osteoporotic fracture is related to peak bone mass achieved at skeletal maturity and subsequent bone loss. Although premature menopause is a risk factor for osteoporosis, the effect of exposure to endogenous estrogen during a woman's reproductive years is poorly characterized. We analyzed the relationship between reproductive factors and estrogen exposure on bone mineral density (BMD) and incidence of atraumatic fracture in data from 1091 women (age: 70 +/- 7.2 yr; mean +/- SD) participating in the Dubbo Osteoporosis Epidemiology Study. Age- and weight-adjusted BMD among women who had used estrogen replacement therapy (ERT) for more than 5 yr was higher at the lumbar spine and femoral neck by 13.7% and 10.2% (P < 0.001), respectively, compared with women who had used ERT for less than 5 yr or nonusers. Duration of exposure to estrogen (years of menstruation plus postmenopausal ERT use) was associated with higher BMD, such that BMD increased by 2-3% for every 10-yr increase in years of estrogen exposure; thus women who menstruated for more than 40 yr had a 6-8% higher BMD than did women who menstruated for less than 30 yr. Higher BMD was also significantly associated with high parity, such that nulliparous women had 5-6% lower BMD than did their peers of the same age and weight. The incidence of atraumatic fractures among non-ERT users was higher than that of ERT-users [odds ratio (OR): 1.06; 95% confidence interval (CI): 0.94-1.16] and was significantly lower among parous women than among nulliparous women (OR 0.94; 95% CI: 0.84-0.98) in univariate analysis. Longer duration of menstruation was associated with lower fracture incidence (OR for 1 SD = 6.6 yr: 0.93; 95% CI: 0.86-1.02). Moreover, when all of these factors were considered simultaneously, parity remained a significant determinant of fracture as well as femoral neck BMD. We conclude that high parity and longer duration of exposure to estrogen, either through natural menstruation or postmenopausal ERT, have protective effects on BMD and are associated with a reduced incidence of atraumatic fracture in a population-based study.
骨质疏松性骨折的风险与骨骼成熟时达到的峰值骨量以及随后的骨质流失有关。尽管过早绝经是骨质疏松症的一个危险因素，但女性生殖年限内暴露于内源性雌激素的影响却鲜有明确阐述。我们在参与达博骨质疏松症流行病学研究的1091名女性（年龄：70±7.2岁；均值±标准差）的数据中，分析了生殖因素和雌激素暴露与骨密度（BMD）及非创伤性骨折发生率之间的关系。与使用雌激素替代疗法（ERT）少于5年的女性或未使用者相比，使用ERT超过5年的女性在腰椎和股骨颈的年龄及体重校正后的骨密度分别高出13.7%和10.2%（P<0.001）。雌激素暴露持续时间（月经年限加绝经后ERT使用年限）与较高的骨密度相关，即雌激素暴露年限每增加10年，骨密度增加2 - 3%；因此，月经超过40年的女性比月经少于30年的女性骨密度高6 - 8%。较高的骨密度也与高生育次数显著相关，未生育女性的骨密度比同年龄、同体重的同龄人低5 - 6%。在单因素分析中，未使用ERT者的非创伤性骨折发生率高于ERT使用者[比值比（OR）：1.06；95%置信区间（CI）：0.94 - 1.16]，且经产妇的骨折发生率显著低于未产妇（OR 0.94；95% CI：0.84 - 0.98）。月经持续时间较长与较低的骨折发生率相关（每标准差 = 6.6年的OR：0.93；95% CI：0.86 - 1.02）。此外，当同时考虑所有这些因素时，生育次数仍然是骨折以及股骨颈骨密度的一个重要决定因素。我们得出结论，在一项基于人群的研究中，高生育次数以及通过自然月经或绝经后ERT延长雌激素暴露时间，对骨密度具有保护作用，并与降低非创伤性骨折的发生率相关。
