Radial bone mineral density in pre- and perimenopausal women: a prospective study of rates and risk factors for loss

Follicle-stimulating hormone and blood lead levels with bone mineral density and the risk of fractures in pre- and postmenopausal women

BACKGROUND

The conclusions on the associations of serum follicle-stimulating hormone (FSH) and blood lead levels with bone mineral density (BMD) were controversial. Furthermore, little was known on the impacts of co-existence of serum FSH and blood lead levels on BMD and the risk of fractures in premenopausal and postmenopausal women. Therefore, the present study aimed to examine the associations of serum FSH and blood lead levels with BMD and the risk of fractures in premenopausal and postmenopausal women.

METHODS

Data were derived from the National Health and Nutrition Examination Survey. FSH is assayed using the Microparticle Enzyme Immunoassay technology. Blood lead levels were measured using atomic absorption spectrometry. BMD was measured using dual energy X-ray absorptiometry. Fractures were defined as subjects with fractures in any site of hip, wrist, and spine.

RESULTS

This study included 3798 participants. Elevated blood lead levels were associated with increased serum FSH levels (β= 48.22, 95% CI: 40.21~ 56.22). Serum FSH levels were negatively associated with total femur BMD in pre- and postmenopausal women. However, elevated serum FSH levels were associated with a lower lumbar spine BMD and a higher risk of fractures only in postmenopausal women (β= -0.0010, 95% CI: -0.0015~ -0.0006; OR: 1.007, 95% CI: 1.000~1.014, respectively).

CONCLUSIONS

Serum lead levels were associated with serum FSH levels. Serum FSH levels were associated with a lower BMD and a higher risk of fractures.

What is normal bone health? A bioarchaeological perspective on meaningful measures and interpretations of bone strength, loss, and aging

Bioarchaeological (the study of archeological human remains together with contextual and documentary evidence) offers a unique vantage point to examine variation in skeletal morphology related to influences such as activity, disease, and nutrition. The human skeleton is composed of a dynamic tissue that is forged by biocultural factors over the entire life course, providing a record of individual, and community history. Various aspects of adult bone health, particularly bone maintenance and loss and the associated skeletal disease osteoporosis, have been examined in numerous past populations. The anthropological study of bone loss has traditionally focused on the signature of postmenopausal aging, costs of reproduction, and fragility in females. The a priori expectation of normative sex-related bone loss/fragility in bioanthropological studies illustrates the wider gender-ideological bias that continues in research design and data analysis in the field. Contextualized data on bone maintenance and aging in the archeological record show that patterns of bone loss do not constitute predictable consequences of aging or biological sex. Instead, the critical examination of bioarchaeological data highlights the complex and changing processes that craft the human body over the life course, and calls for us to question the ideal or "normal" range of bone quantity and quality in the human skeleton, and to critically reflect on what measures are actually biologically and/or socially meaningful.

Grand multiparity associations with low bone mineral density and degraded trabecular bone pattern

Introduction

Pregnancy is associated with changes in bone remodeling and calcium metabolism, which may increase the risk of fragility fracture after menopause. We hypothesized that in postmenopausal women, with history of grand multiparity, the magnitude of trabecular bone deterioration is associated with number of deliveries.

Methods

1217 women aged 69.2 ± 6.4 years, from the Bushehr Elderly Health (BEH) program were recruited. The areal bone mineral density (aBMD) of the lumbar spine and femoral neck and trabecular bone score (TBS) of 916 postmenopausal women, with grand multiparity defined as more than 4 deliveries, were compared with those of 301 postmenopausal women with 4 or fewer deliveries. The association of multiparity with aBMDs and TBS were evaluated after adjustment for possible confounders including age, years since menopause, body mass index, and other relevant parameters.

Results

The aBMD of femoral neck (0.583 ± 0.110 vs. 0.603 ± 0.113 g/cm²), lumbar spine (0.805 ± 0.144 vs. 0.829 ± 0.140 g/cm²) and TBS (1.234 ± 0.086 vs. 1.260 ± 0.089) were significantly lower in women with history of grand multiparity than others. In the multiple regression analysis, after adjusting for confounders, the negative association did persist for lumbar spine aBMD (beta = −0.02, p value = 0.01), and the TBS (beta = −0.01, p value = 0.03), not for femoral neck aBMD.

Conclusion

We infer that grand multiparity have deleterious effects on the aBMD and the trabecular pattern of the lumbar spine.

Bone Mineral Density in Different Menopause Stages is Associated with Follicle Stimulating Hormone Levels in Healthy Women

Although estradiol (E2) has been believed to be the most critical factor in the menopause-associated decrease in bone mineral density (BMD), the role of increasing follicle stimulating hormone (FSH) during menopause is relatively unclear. We determined the extent to which hip and lumbar spine BMD differ among the stages of menopause in healthy women, and whether BMD is associated with FSH and E2 levels. A cross-sectional study of 141 healthy women classified as premenopausal (Pre; 38 ± 6 yrs; mean ± SD, n = 30), early perimenopausal (EPeri; 50 ± 3yrs, n = 31), late perimenopausal (LPeri; 50 ± 4yrs, n = 30), early postmenopausal (EPost; 55 ± 3yrs, n = 24), or late postmenopausal (LPost; 62 ± 4 yrs, n = 26), was conducted. Spine/hip BMD and sex hormones were measured using dual-energy X-ray absorptiometry and enzymatic/colorimetric methods, respectively. Compared to EPeri, spine BMD was lower (p < 0.05) in LPeri, EPost, and LPost and hip BMD was lower (p < 0.05) in EPost and LPost. BMD was inversely associated with FSH (spine: r = -0.341; hip: r = -0.271, p < 0.05) and directly associated with E2 (spine: r = 0.274; hip: r = 0.256, p < 0.05). The menopause-related loss of spine and hip BMD is associated not only with low E2 but also higher FSH. Future studies are essential to delineating the mechanisms by which FSH regulates bone health in aging women.

Effect of parity on bone mineral density: A systematic review and meta-analysis

INTRODUCTION

Parity has been suggested as a possible factor affecting bone health in women. However, study results on its association with bone mineral density are conflicting.

METHODS

PubMed, EMBASE, the Cochrane Library, and Korean online databases were searched using the terms "parity" and "bone mineral density", in May 2016. Two independent reviewers extracted the mean and standard deviation of bone mineral density measurements of the femoral neck, spine, and total hip in nulliparous and parous healthy women.

RESULTS

Among the initial 10,146 studies, 10 articles comprising 24,771 women met the inclusion criteria. The overall effect of parity on bone mineral density was positive (mean difference=5.97mg/cm²; 95% CI 2.37 to 9.57; P=0.001). The effect appears site-specific as parity was not significantly associated with the bone mineral density of the femoral neck (P=0.09) and lumbar spine (P=0.17), but parous women had significantly higher bone mineral density of the total hip compared to nulliparous women (mean difference=5.98mg/cm²; 95% CI 1.72 to 10.24; P=0.006). No obvious heterogeneity existed among the included studies (femoral neck I²=0%; spine I²=31%; total hip I²=0%).

CONCLUSION

Parity has a positive effect on bone in healthy, community-dwelling women and its effect appears site-specific.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Effects of dioxin-related compounds on bone mineral density in patients affected by the Yusho incident

Exposure to dioxin-related compounds results in many adverse health effects. Several studies have examined the effects of dioxin-related compounds on human bone metabolism with inconsistent results. In Japan in 1968, accidental human exposure to rice oil contaminated with dioxin-related compounds led to the development of Yusho oil disease. The aim of this study was to determine whether exposure to dioxin-related compounds was associated with bone mineral density in Yusho patients. In 2010, 262 women and 227 men underwent dual-energy X-ray absorptiometry bone scans as part of the nationwide Yusho health examination. Serum levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls were measured using high-resolution gas chromatography and high-resolution mass spectrometry. When adjusted for prefecture, 1,2,3,4,7,8-HxCDD and 2,3,7,8-TCDF were significantly positively associated with Z-scores in men. No congeners were positively associated with Z-scores in women. After adjustment for prefecture and body mass index, one congener, 1,2,3,4,6,7,8-HpCDD, was negatively associated with Z-scores in women. In contrast, no congeners remained significant in men after adjusting for body mass index. This may suggest that 1,2,3,4,6,7,8-HpCDD has a negative effect on bone mineral density in women; however, the findings should be interpreted carefully, because no increase in the serum level of this congener was observed in patients with Yusho disease.

Smoking and body fat mass in relation to bone mineral density and hip fracture: the Hordaland Health Study

Lower bone mineral density (BMD) in smokers may be attributable to lower body weight or fat mass, rather than to a direct effect of smoking. We analyzed the effects of smoking exposure, assessed by plasma cotinine, and body fat on BMD and the risk of subsequent hip fracture. In the community-based Hordaland Health Study (HUSK), 3003 participants 46-49 years and 2091 subjects 71-74 years were included. Cotinine was measured in plasma and information on health behaviors was obtained from self-administered questionnaires. BMD and total body soft tissue composition were measured by dual X-ray absorptiometry. Information on hip fracture was obtained from computerized records containing discharge diagnoses for hospitalizations between baseline examinations 1997-2000 through December 31st, 2009. In the whole cohort, moderate and heavy smokers had stronger positive associations between fat mass and BMD compared to never smokers (differences in regression coefficient (95% CI) per % change in fat mass = 1.38 (0.24, 2.52) and 1.29 (0.17, 2.4), respectively). In moderate and heavy smokers there was a nonlinear association between BMD and fat mass with a stronger positive association at low compared to high levels of fat mass (Davies segmented test, p<0.001). In elderly women and men, heavy smokers had an increased risk of hip fracture compared to never smokers (hazard ratio = 3.31, 95% CI: 2.05, 5.35; p<0.001). In heavy smokers there was a tendency of a lower risk of hip fracture with higher percentage of fat mass. The deleterious effect of smoking on bone health is stronger in lean smokers than in smokers with high fat mass.

Serum dioxin concentrations and bone density and structure in the Seveso Women's Health Study

BACKGROUND

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a widespread environmental contaminant, is a known endocrine disruptor. In animal studies, TCDD exposure impairs bone metabolism and increases fragility. To our knowledge, no epidemiologic studies have examined this association.

OBJECTIVES

On 10 July 1976, a chemical explosion in Seveso, Italy, resulted in the highest known residential exposure to TCDD. In 1996, we initiated the Seveso Women's Health Study, a retrospective cohort study of the health of the women. In 2008, we followed up the cohort. Here, we evaluated the association between TCDD exposure and bone structure and geometry in adulthood, and considered whether timing of TCDD exposure before achievement of peak bone mass (assumed to occur 2 years after onset of menarche) modified the association.

METHODS

Individual TCDD concentration was measured in archived serum collected soon after the explosion. In 2008, 350 women who were <20 years old in 1976 underwent a dual-energy X-ray absorptiometry (DXA) bone scan. Bone mineral density was measured at the lumbar spine and hip, and hip geometry was extracted from hip DXA scans using the hip structural analysis method.

RESULTS

Among premenopausal women, TCDD serum levels were associated with some indexes indicating better bone structure in women exposed before peak bone mass (n=219), with stronger associations in those exposed before 5 years of age (n=46). In contrast, among postmenopausal women, TCDD levels were associated with evidence of better bone structure in women exposed after peak bone mass (n=48) than in other women (n=18).

CONCLUSIONS

Our current results do not support the hypothesis that postnatal TCDD exposure adversely affects adult bone health. Continued follow-up of women who were youngest at exposure is warranted. Future studies should also focus on those exposed in utero.

Bone mineral density assessment in premenopausal women

In the absence of fragility fractures, low bone mineral density may reflect attainment of a lower peak bone mass in comparison with the young adult mean value. It is necessary to distinguish between low peak bone mass and a systemic disorder resulting in low bone mineral density and skeletal fragility. Low peak bone mass in the absence of fragility fracture or progressive bone loss may not require pharmacological intervention. However, systemic disorders contributing to bone loss do require diagnosis and intervention. Common causes of low bone density in premenopausal women include ovulatory disturbances and low body weight. Other diseases, conditions or medications may also contribute to bone loss and these should be identified and treated if present. Fracture risk is reduced by lifestyle changes and pharmacological intervention in those with glucocorticoid-induced bone loss. Discontinuing depo medroxyprogesterone acetate use has been associated with improvements in bone mineral density. Bone mineral density alone is insufficient for the diagnosis of osteoporosis in premenopausal women in the absence of fragility fractures. Bone mineral density testing should only be performed in premenopausal women in the presence of approved indications.

The relationship between bone turnover markers and BMD decreasing rates in Chinese middle-aged women

BACKGROUND

The relationship between bone turnover markers (BTMs) and BMD decreasing rate (BDR) in Chinese women is unclear. Wu investigated the relationship between (BTMs) and BDR at various skeletal sites in Chinese middle-aged women.

METHODS

A cross-section study of 555 healthy Chinese women over 35-60years of age. BMD at posteroanterior spine, the left hip, and the left forearm were measured with a DXA. Levels of serum osteocalcin (OC), bone-specific alkaline phosphatase (BAP), cross-linked N-terminal telopeptides of type I collagen (sNTX) and total urinary deoxypyridinoline (uDPD) were determined.

RESULTS

BDR at various skeletal sites had significant negative correlation with serum OC(r=-0.395 to -0.530), BAP(r=-0.297 to -0.486), and sNTX(r=-0.207 to -0.272). After adjustment of age and weight, serum OC, BAP, and sNTX rather than total uDPD still exhibited significant correlations with BDR. Stepwise regression analyses showed that, serum OC and BAP were the significantly negative determinants of BDR. Between 4.7-27.7% and 1.2-16.1% of the changes in BDR were determined by serum OC and BAP, respectively. However, sNTX and total uDPD had no significant effect on BDR at various skeletal sites.

CONCLUSIONS

This study indicated the correlation between BTMs and early-stage BDR in Chinese middle-aged women and suggested that serum OC and BAP, rather than sNTX and total uDPD, are the key determining factors of early BMD decreases.

Amount of bone loss in relation to time around the final menstrual period and follicle-stimulating hormone staging of the transmenopause

BACKGROUND AND OBJECTIVE

The objective of the study was to describe bone loss rates across the transmenopause related to FSH staging and the final menstrual period (FMP).

DESIGN AND SETTING

This was a population-based cohort of 629 women (baseline age 24-44 yr) with annual data points over 15 yr.

MEASUREMENTS

Measures were bone mineral density (BMD), FSH to define four FSH stages, and menstrual bleeding cessation to define the FMP. Bone loss rates were reported by obesity status.

RESULTS

Annualized rates of lumbar spine bone loss began in FSH stage 3, which occurs approximately 2 yr prior to the FMP (1.67%/yr); bone loss continued into FSH stage 4 (1.21%/yr). Mean spine BMD in FSH stage 4 was 6.4% less than spine BMD value in FSH stage 1. Annualized rates of femoral neck (FN) bone loss began in FSH stage 3 (0.55%/yr) and continued into FSH stage 4 (0.72%/yr). The FN difference between mean values in FSH stage 1 and FSH stage 4 was 5%. Annualized rates of spine bone loss in the 2 yr prior to the FMP were 1.7%/yr, 3.3%/yr in the 2 yr after the FMP, and 1.1%/yr in the 2- to 7-yr period after the FMP. Nonobese women had lower BMD levels and greater bone loss rates.

CONCLUSIONS

Spine and FN bone loss accelerates in FSH stage 3. Bone loss also began to accelerate 2 yr before the FMP with the greatest loss occurring in the 2 yr after the FMP. Bone loss rates in both spine and FN BMD were greater in nonobese women than obese women.

Health effects of breast feeding for mothers: a critical review

Lactation results in a number of physiological adaptations which exert direct effects on maternal health, some of which may confer both short and long term advantages for breast feeding mothers. Breast feeding in the early postpartum period promotes a more rapid return of the uterus to its prepregnant state through the actions of oxytocin. Breast feeding may also lead to a more rapid return to prepregnancy weight. Among studies that had good data on duration and intensity of lactation, the majority show a significant association between lactation and weight loss. However, there is no evidence that lactation prevents obesity. Lactation also affects glucose and lipid metabolism. The long term effects of these adaptations are unknown but may have implications for preventing subsequent development of diabetes and heart disease. Lactation delays the return of ovulation and significantly reduces fertility during the period of lactational amenorrhoea. This process is linked with feeding patterns and may therefore be affected by practices such as scheduled feedings and the timing of introduction of complementary foods. While the evidence from epidemiologic studies is mixed, several large studies have shown that extended lactation is associated with reduced risk of premenopausal breast, ovarian and endometrial cancers. Although bone mineralization declines during lactation, repletion takes place after weaning. As a result, breast feeding does not appear to cause long term depletion of bone nor does it increase risk of osteoporosis. Many of the physiological effects of lactation are dependent on the stimulation of the hypothalamic-pituitary axis and milk removal and thus may vary with infant feeding practices. Well controlled studies are needed that include detailed information regarding infant feeding practices in addition to the total duration of any breast feeding. Future feeding recommendations should reflect careful consideration of how such practices affect both infant and maternal health.

Pregnancy- and lactation-associated osteoporosis with severe vertebral deformities: can strontium ranelate be a new alternative for the treatment?

BACKGROUND CONTEXT

Pregnancy- and lactation-associated osteoporosis is an uncommon condition that may be a consequence of preexisting low bone density, loss of bone mineral content during pregnancy, and increased bone turnover.

PURPOSE

To present a case of severe osteoporosis associated with pregnancy and lactation and its treatment protocol.

STUDY DESIGN/SETTING

A tertiary care hospital.

PATIENT SAMPLE

A young female after twin pregnancy presenting with severe osteoporosis.

METHODS

The diagnosis was done on the basis of bone mineral density (BMD) measurement. The patient was treated with first alendronate and then strontium ranelate. She was considered as a candidate for kyphoplasty.

RESULTS

A dramatic increase in the BMD and palliation of back pain were observed.

CONCLUSIONS

Strontium ranelate may be a new alternative in the treatment of pregnancy- and lactation-associated osteoporosis.

Bivariate genome-wide linkage analysis for traits BMD and AAM: effect of menopause on linkage signals

Osteoporosis is an age-related systemic skeletal disease, characterized by low bone mineral density (BMD). Low BMD is closely associated with late age at menarche (AAM). Our previous bivariate genome-wide linkage analyses (GWLAs) between BMD and AAM identified two shared genomic regions in 2584 Caucasian females including both pre- and post-menopausal females. However, menopause often causes dramatic bone loss in post-menopausal females; this may introduce some confounding effects on the bivariate GWLA for BMD and AAM. To address the effect of menopause on the identification of genetic factors shared by BMD and AAM, we segregated the previously studied population of 2584 females into two separate subgroups consisting of 1462 pre-menopause subjects and 1122 post-menopausal subjects, and performed further bivariate GWLAs. The BMD was measured by Hologic Dual-energy X-ray (DXA) scanners (Hologic Inc., Bedford, MA, USA). Based on the genome-wide thresholds corrected for multiple testing, we found more significant genomic regions in the pre-menopausal group than in total group (including pre- and post-menopausal women), e.g., we found 4, 1, and 2 shared by spine BMD and AAM, femoral neck (FNK) BMD and AAM and ultra distal (UD) BMD and AAM, respectively. We did not found any significant linkage signals in the post-menopausal group. Importantly, the linkage signals at all significant regions were much stronger in pre-menopausal group than in the other groups: post-menopausal females and total females. For example, the linkage LOD score for FNK BMD and AAM is as high as 4.88 in pre-menopausal females, but only 0.24 and 0.31 in post-menopausal and total females, respectively. These results suggest that menopause introduces some noise signals into GWLAs when estimating the shared genetic factors by BMD and AAM. Therefore, it is very important to classify female subjects properly according to their menopause stage when performing such studies.

Bone mineral density changes during the menopause transition in a multiethnic cohort of women

CONTEXT

Rates of bone loss across the menopause transition and factors associated with variation in menopausal bone loss are poorly understood.

OBJECTIVE

Our objective was to assess rates of bone loss at each stage of the transition and examine major factors that modify those rates.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a longitudinal cohort study of 1902 African-American, Caucasian, Chinese, or Japanese women participating in The Study of Women's Health Across the Nation. Women were pre- or early perimenopausal at baseline.

OUTCOME MEASURE

We assessed bone mineral density (BMD) of the lumbar spine and total hip across a maximum of six annual visits.

RESULTS

There was little change in BMD during the pre- or early perimenopause. BMD declined substantially in the late perimenopause, with an average loss of 0.018 and 0.010 g/cm2.yr from the spine and hip, respectively (P<0.001 for both). In the postmenopause, rates of loss from the spine and hip were 0.022 and 0.013 g/cm2.yr, respectively (P<0.001 for both). During the late peri- and postmenopause, bone loss was approximately 35-55% slower in women in the top vs. the bottom tertile of body weight. Apparent ethnic differences in rates of spine bone loss were largely explained by differences in body weight.

CONCLUSIONS

Bone loss accelerates substantially in the late perimenopause and continues at a similar pace in the first postmenopausal years. Body weight is a major determinant of the rate of menopausal BMD loss, whereas ethnicity, per se, is not. Healthcare providers should consider this information when deciding when to screen women for osteoporosis.

Genetic effects on bone loss in peri- and postmenopausal women: a longitudinal twin study

This longitudinal twin study was designed to assess the heritability of bone loss in peri- and postmenopausal women. A sample of 724 female twins was studied. Baseline and repeat BMD measurements were performed. Results of genetic model-fitting analysis indicated genetic effects on bone loss account for approximately 40% of the between-individual variation in bone loss at the lumbar spine, forearm, and whole body.

INTRODUCTION

BMD and bone loss are important predictors of fracture risk. Although the heritability of peak BMD is well documented, it is not clear whether bone loss is also under genetic regulation. This study was designed to assess the heritability of bone loss in peri- and postmenopausal women.

MATERIALS AND METHODS

A sample of 724 female twins (177 monozygotic [MZ] and 185 dizygotic [DZ] pairs), 45-82 yr of age, was studied. Each individual had baseline BMD measurements at the lumbar spine, hip, forearm, and total body by DXA and at least one repeat measure, on average 4.9 yr later. Change in BMD (DeltaBMD) was expressed as percent of gain or loss per year. Intraclass correlation coefficients for DeltaBMD were calculated for MZ and DZ pairs. Genetic model-fitting analysis was conducted to partition the total variance of DeltaBMD into three components: genetic (G), common environment (C), and specific environment, including measurement error (E). The index of heritability was estimated as the ratio of genetic variance over total variance.

RESULTS

The mean annual DeltaBMD was -0.37 +/- 1.43% (SD) per year at the lumbar spine, -0.27 +/- 1.32% at the total hip, -0.77 +/- 1.66% at the total forearm, -0.36 +/- 1.56% at the femoral neck, and -0.16 +/- 0.81% at the whole body. Intraclass correlation coefficients were significantly higher in MZ than in DZ twins for all studied parameters, except at the hip sites. Results of genetic model-fitting analysis indicated that the indices of heritability for DeltaBMD were 0.38, 0.49, and 0.44 for the lumbar spine, total forearm, and whole body, respectively. However, the genetic effect on DeltaBMD at all hip sites was not significant.

CONCLUSIONS

These data suggest that, although genetic effects on bone loss with aging are less pronounced than on peak bone mass, they still account for approximately 40% of the between-individual variation in bone loss for the lumbar spine, total forearm, and whole body in peri- and postmenopausal women. These findings are relevant for studies aimed at identification of genes that are involved in the regulation of bone loss.

Age-related bone mineral density, bone loss rate, prevalence of osteoporosis, and reference database of women at multiple centers in China

Our study surveyed age-related bone mineral density (BMD), bone loss rate, and prevalence of osteoporosis in women at multiple research centers in China. Survey results were used to establish a BMD reference database for the diagnosis of osteoporosis in Chinese women nationwide. We used dual-energy X-ray absorptiometry bone densitometers to measure BMD at posteroanterior (PA) lumbar spine (L1-L4; n=8142) and proximal femur (n=7290) in female subjects of age 20-89 yr from Beijing, Shanghai, Guangzhou, Chengdu, Nanjing, and Jiaxing. A cubic regression-fitting model was used to describe the change of BMD with age at various skeletal sites. Peak BMD occurred between 30 and 34 yr of age for femur neck and total femur, and between 40 and 44 yr for spine and trochanter measurement sites. Young adult (YA) BMD values (mean and standard deviation [SD], calculated as the average BMD in the age range of 20-39, were 1.116+/-0.12, 0.927+/-0.12, 0.756+/-0.11, and 0.963+/-0.13 g/cm2 at PA spine, femoral neck, trochanter, and total femur, respectively. The BMD of 85-yr-old women reflected a loss of 32% at the spine and 30-35% at femur measurement sites. The prevalence of osteoporosis, defined as a BMD of <or=-2.5 SDs from YA values established in this study, in female subjects of age 50 yr or older, was 28% for the spine, 15% for any femur site, and 31% for any spine or femur site. This study provides important information for formulating osteoporosis prevention and treatment strategies in Chinese women, and it establishes a reliable BMD reference database for the diagnosis of osteoporosis of Chinese women nationwide.

Body mass index and gynecological factors as determinants of bone mass in healthy Moroccan women

Several studies have shown that low body mass index (BMI) is associated with low BMD and fractures. However, the results that have been published from studies on reproductive factors and BMD are extremely controversial, with some demonstrating a beneficial effect, while others show a detrimental impact of these factors on bone mass.

OBJECTIVE

To study the influence of several gynecological factors (years since menopause (YSM), age at menarche and gynecological age or reproductive life) simultaneously with anthropometric factors as determinants of bone mineral density (BMD) in healthy women older than 40.

METHODS

BMD was determined by dual energy X-ray absorptiometry (DXA) at the lumbar spine and femurs in women aged >40 randomly chosen from the population of Rabat with a cluster sampling method.

RESULTS

Four hundred and twenty-two healthy women older than 40 years were included in the study. The mean age was 57.2 years (8.4) [40-79] and the mean number of parities was 4.42 (2.9) [0-14]. Osteoporosis according to the classification of WHO (T-score<or=-2.5) was observed in 133 women (32.2%). The increase in the number of parities was associated to a larger body mass index and a lower BMD as well in the hips and the lumbar spine after adjustment for age. The comparison of groups of patients according to the age at menarche, the age at menopause or the period of fertility did not highlight an association with BMD. BMD at the lumbar spine and the hips was correlated negatively with age, YSM and parity and positively with BMI. Multivariate analysis showed that the determinant of BMD are BMI (OR=0.88; 95% CI: 0.83-0.92), parity (OR=1.10; 1.01-1.56) and YSM (OR=1.06; 1.03-1.10).

CONCLUSION

Bone loss in women older than 40 is a function of aging, parity and years since menopause; and there is a definite bone-protective effect of body mass weight. Further studies are required to evaluate the role of these parameters in the fracture risk.

Effect of raloxifene on bone mineral density in premenopausal women at increased risk of breast cancer

CONTEXT

Raloxifene is a promising breast cancer prevention agent in postmenopausal women at increased risk for breast cancer. The effects of raloxifene in premenopausal women are unknown.

OBJECTIVE

We evaluated the effect of raloxifene in premenopausal women at increased risk for breast cancer on bone mineral density (BMD).

DESIGN

This was a phase II clinical trial.

SETTING

This study was conducted at an academic medical center.

PARTICIPANTS

Thirty-seven premenopausal women at increased risk for breast cancer enrolled in the trial. Thirty subjects began treatment and 27 were evaluable.

INTERVENTION

Raloxifene (60 mg daily) and elemental calcium (500 mg daily) were given for 2 yr. Subjects were followed up off medications for 1 yr.

MAIN OUTCOME MEASURE

The primary end point was the intrasubject percent change in BMD at 1 yr measured by dual-energy x-ray absorptiometry.

RESULTS

The mean baseline lumbar spine density was 1.027 g/cm(2). Lumbar spine density decreased 2.3% at 1 yr (P < 0.00001) and 3.5% at 2 yr (P < .00001). Percent change from yr 2 to 3 was +1.4%. The mean baseline total hip bone density was 0.905 g/cm(2). Total hip density decreased 0.3% at 1 yr and 1.0% at 2 yr (P = 0.033). Percent change from yr 2 to 3 was +1.7%.

CONCLUSIONS

Raloxifene use is associated with a decrease in BMD in premenopausal women at increased risk for breast cancer. The clinical significance of this decrease is unknown and is attenuated with stopping raloxifene.

Physical activity in the prevention and amelioration of osteoporosis in women : interaction of mechanical, hormonal and dietary factors

Osteoporosis is a serious health problem that diminishes quality of life and levies a financial burden on those who fear and experience bone fractures. Physical activity as a way to prevent osteoporosis is based on evidence that it can regulate bone maintenance and stimulate bone formation including the accumulation of mineral, in addition to strengthening muscles, improving balance, and thus reducing the overall risk of falls and fractures. Currently, our understanding of how to use exercise effectively in the prevention of osteoporosis is incomplete. It is uncertain whether exercise will help accumulate more overall peak bone mass during childhood, adolescence and young adulthood. Also, the consistent effectiveness of exercise to increase bone mass, or at least arrest the loss of bone mass after menopause, is also in question. Within this framework, section 1 introduces mechanical characteristics of bones to assist the reader in understanding their responses to physical activity. Section 2 reviews hormonal, nutritional and mechanical factors necessary for the growth of bones in length, width and mineral content that produce peak bone mass in the course of childhood and adolescence using a large sample of healthy Caucasian girls and female adolescents for reference. Effectiveness of exercise is evaluated throughout using absolute changes in bone with the underlying assumption that useful exercise should produce changes that approximate or exceed the absolute magnitude of bone parameters in a healthy reference population. Physical activity increases growth in width and mineral content of bones in girls and adolescent females, particularly when it is initiated before puberty, carried out in volumes and at intensities seen in athletes, and accompanied by adequate caloric and calcium intakes. Similar increases are seen in young women following the termination of statural growth in response to athletic training, but not to more limited levels of physical activity characteristic of longitudinal training studies. After 9-12 months of regular exercise, young adult women often show very small benefits to bone health, possibly because of large subject attrition rates, inadequate exercise intensity, duration or frequency, or because at this stage of life accumulation of bone mass may be at its natural peak. The important influence of hormones as well as dietary and specific nutrient abundance on bone growth and health are emphasised, and premature bone loss associated with dietary restriction and estradiol withdrawal in exercise-induced amenorrhoea is described. In section 3, the same assessment is applied to the effects of physical activity in postmenopausal women. Studies of postmenopausal women are presented from the perspective of limitations of the capacity of the skeleton to adapt to mechanical stress of exercise due to altered hormonal status and inadequate intake of specific nutrients. After menopause, effectiveness of exercise to increase bone mineral depends heavily on adequate availability of dietary calcium. Relatively infrequent evidence that physical activity prevents bone loss or increases bone mineral after menopause may be a consequence of inadequate calcium availability or low intensity of exercise in training studies. Several studies with postmenopausal women show modest increases in bone mineral toward the norm seen in a healthy population in response to high-intensity training. Physical activities continue to stimulate increases in bone diameter throughout the lifespan. These exercise-stimulated increases in bone diameter diminish the risk of fractures by mechanically counteracting the thinning of bones and increases in bone porosity. Seven principles of bone adaptation to mechanical stress are reviewed in section 4 to suggest how exercise by human subjects could be made more effective. They posit that exercise should: (i) be dynamic, not static; (ii) exceed a threshold intensity; (iii) exceed a threshold strain frequency; (iv) be relatively brief but intermittent; (v) impose an unusual loading pattern on the bones; (vi) be supported by unlimited nutrient energy; and (vii) include adequate calcium and cholecalciferol (vitamin D3) availability.

High bone mineral density among perimenopausal women

Studies regarding high bone mineral density (HBMD) are few. In the population-based Kuopio Osteoporosis Risk Factor and Prevention Study, BMDs of women were measured from 1990-1991 and 1995-1997. The mean age of the 1,873 women studied was 53.5 years at baseline (range 48.0-59.6). In all, 248 women were excluded because of BMD measurement errors or artifacts: 41 from the HBMD group (20.6%) and 207 (12.4%) from the control group. The final study group consisted of 1,551 women, 168 in the HBMD group (baseline lumbar BMD >1.23 g/cm2; femoral BMD >1.01 g/cm2, and 5-year follow-up lumbar BMD >1.21 g/cm2; femoral BMD >0.98 g/cm2, respectively) and 1,383 in the control group. The predictors for HBMD in the multivariate regression analysis were as follows: hormone therapy (HT) during the follow-up from 0.5 to 2 years and for over 2 years (OR 2.06, CI: 1.11-3.81 and OR 2.16, CI 1.43-3.26) and being overweight (BMI from 25 kg/m2 to 30 kg/m2, and BMI >30 kg/m2) at baseline (OR 2.84, CI: 1.82-4.42; OR 5.94, CI: 3.47-10.16, respectively). High physical activity while 11-18 years of age was associated with HBMD (OR 1.69, CI: 1.17-2.45). Parity predicted HBMD so that after one to two births the OR was 2.66 (CI: 1.03-6.88) and 3.03 (CI: 1.16-7.90) after three or more births. Menopause was negatively associated with HBMD (OR 0.57, CI 0.38-0.85). There were more premenopausal women in the HBMD group (53.9 vs. 34.6%, P <0.001). The HBMD group showed fewer fractures. In conclusion, being overweight, parity, HT use, premenopause and high physical activity in adolescence seemed to be predictors for persistently high BMD in early postmenopausal women. We suggest that the fracture risk is low in these women, and thus they are neither primary candidates for BMD screening nor for osteoporosis medication.

Longitudinal changes in forearm bone mineral density in women and men aged 25-44 years: the Tromsø study: a population-based study

The aim of this study was to describe and compare bone mineral density (BMD) development in Norwegian women and men aged 25-44 years in a population-based, longitudinal study. BMD was measured twice at distal and ultradistal forearm sites by single x-ray absorptiometry in 258 women and 147 men (mean follow-up time, 6.4 (standard deviation, 0.6) years). At the distal site, a small annual gain of approximately 0.1% became a small loss beginning at age 34 years in men and age 36 years in women. At the ultradistal site, BMD change was predicted by age in women only, and bone loss started at age 38 years. A high degree of tracking of BMD measurements was observed for both sexes and both sites, r > 0.93. Depending on total BMD change, participants were grouped into "losers", "nonlosers", and "gainers", and more than 6% lost more than the smallest detectable amount of BMD: > or =3.46% at the distal site and > or =5.14% at the ultradistal site. In both sexes, bone mineral content (grams) decreased, whereas area (centimeters squared) increased significantly in "losers" compared with "gainers". This finding might represent physiologic compensation preserving bone strength. No cohort effects were observed when 1994 and 2001 measures from similar age groups were compared.

Prevention and treatment of postmenopausal osteoporosis

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of the skeleton leading to enhanced bone fragility and an increased risk of fracture. Prior to fracture, diagnosis is established by documenting low bone mass. In the first section of this article we review the clinical use of bone mass measurements and biochemical markers of bone remodeling in selecting patients most in need of preventive therapy at menopause. Women with high bone turnover lose bone at menopause more rapidly than those with normal bone turnover and are more likely to derive benefit from the several preventive therapies available. The second section addresses the available technologies used to diagnose osteoporosis and/or establish fragility fracture risk using noninvasive bone mass measurement and biochemical markers of bone remodeling separately or in combination. In the third section we review the several treatment options available for patients with osteoporosis, including alendronate (alendronic acid), risendronate (risedronic acid), calcitonin, teriparatide, and raloxifene, and the approaches to monitoring the therapeutic response. The final section deals with fall protection--an often forgotten aspect of management of the patient at risk for sustaining and osteoporotic fragility fracture.

Alcohol intake as a risk factor for fracture

High intakes of alcohol have adverse effects on skeletal health, but evidence for the effects of moderate consumption are less secure. The aim of this study was to quantify this risk on an international basis and explore the relationship of this risk with age, sex, and bone mineral density (BMD). We studied 5,939 men and 11,032 women from three prospectively studied cohorts comprising CaMos, DOES, and the Rotterdam Study. Cohorts were followed for a total of 75,433 person-years. The effect of reported alcohol intake on the risk of any fracture, any osteoporotic fracture, and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined included age and BMD. The results of the different studies were merged using weighted beta-coefficients. Alcohol intake was associated with a significant increase in osteoporotic and hip fracture risk, but the effect was nonlinear. No significant increase in risk was observed at intakes of 2 units or less daily. Above this threshold, alcohol intake was associated with an increased risk of any fracture (risk ratio [RR] = 1.23; 95% CI, 1.06-1.43), any osteoporotic fracture (RR = 1.38; 95% CI, 1.16-1.65), or hip fracture (RR = 1.68; 95% CI, 1.19-2.36). There was no significant interaction with age, BMD, or time since baseline assessment. Risk ratios were moderately but not significantly higher in men than in women, and there was no evidence for a different threshold for effect by gender. We conclude that reported intake of alcohol confers a risk of some importance beyond that explained by BMD. The validation of this risk factor on an international basis permits its use in case-finding strategies.

Idiopathic osteoporosis in premenopausal women

Although osteoporosis predominantly affects older postmenopausal women, low bone mineral density also occurs in men and younger women. In men, it is often unexplained by recognized secondary causes. These men with idiopathic osteoporosis have reductions in serum IGF-I as well as indices of reduced bone formation. Younger women also experience bone loss of unknown etiology (IOP). Whether premenopausal women with IOP have similar decreases in IGF-I levels and reduced indices of bone formation is unknown. We prospectively evaluated a group of premenopausal women with unexplained low bone mass and compared them to normal premenopausal women with respect to serum concentrations of IGF-I. Thirteen premenopausal women (34.2+/-2.3 years) with low bone density (mean lumbar spine T-score -2.26+/-0.20) were compared with 13 premenopausal women (35.7+/-1.7 years) with normal bone density of similar age, height and ethnic composition. Body mass index (BMI) was lower in subjects than controls (20.5+/-0.7 versus 25.2+/-1.1 kg/m(2), P<0.01). A family history of osteoporosis and a history of fragility fractures were found more frequently in subjects than controls (P< or =0.05). Calciotropic hormones did not differ between the two groups. In contrast to our observations in men with idiopathic osteoporosis, mean serum IGF-I concentrations did not differ between subjects and controls (subjects: 22.5+/-2.2 nmol/l versus controls: 20.8+/-1.6 nmol/l; NS). Moreover, serum IGF-I levels did not correlate significantly with serum estradiol or with BMD at either the lumbar spine or femoral neck. However, lower follicular phase serum estradiol levels among non-oral contraceptive users were found in subjects as compared to controls (subjects: 124.1+/-13 pmol/l versus controls 194.9+/-24 pmol/l, P=0.06). Calculated free, bioavailable estradiol levels were significantly lower overall in subjects than controls (0.6+/-0.1 versus 1.2+/-0.2 pmol/l, P<0.05). Total serum estradiol levels correlated with BMD at the femoral neck (r=+0.50; P<0.05). Free, bioavailable estradiol correlated with BMD and BMAD at the lumbar spine (r=+0.54, P<0.01 and r=+0.54, P<0.05, respectively) and femoral neck (r=+0.60 and r=+0.55 respectively, both P<0.01). Urinary NTX excretion, although within the normal premenopausal range, was 45% higher in subjects than controls (41.6+/-5.9 nmol BCE/l versus 28.3+/-2.4 nmol BCE/l; P<0.05). Bone-specific alkaline phosphatase activity was also higher (17.4+/-1.6 ng/ml versus 14.7+/-0.8 ng/ml), although the difference was not statistically significant. These results suggest differences in the pathogenesis of idiopathic osteoporosis in women as compared to men with IOP.

Medieval trabecular bone architecture: the influence of age, sex, and lifestyle

Osteoporosis has become a growing health concern in developed countries and an extensive area of research in skeletal biology. Despite numerous paleopathological studies of bone mass, few studies have measured bone quality in past populations. In order to examine age- and sex-related changes in one aspect of bone quality in the past, a study was made of trabecular bone architecture in a British medieval skeletal sample. X-ray images of 5-mm-thick coronal lumbar vertebral bone sections were taken from a total of 54 adult individuals divided into three age categories (18-29, 30-49, and 50+ years), and examined using image analysis to evaluate parameters related to trabecular bone structure and connectivity. Significant age-related changes in trabecular bone structure (trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp), and anisotropic ratio (Tb.An)) were observed to occur primarily by middle age with significant differences between the youngest and two older age groups. Neither sex showed continuing change in trabecular structure between the middle and old age groups. Age-related changes in bone connectivity (number of nodes (N.Nd) and node-to-node strut length (Nd.Nd)) similarly indicated a change in bone connectivity only between the youngest and two older age groups. However, females showed no statistical differences among the age groups in bone connectivity. These patterns of trabecular bone loss and fragility contrast with those generally found in modern populations that typically report continuing loss of bone structure and connectivity between middle and old age, and suggest greater loss in females. The patterns of bone loss in the archaeological samples must be interpreted cautiously. We speculate that while nutritional factors may have initiated some bone loss in both sexes, physical activity could have conserved bone architecture in old age in both sexes, and reproductive factors such as high parity and extended periods of lactation could have played a key role in female bone maintenance in this historic population. The study of qualitative elements (such as trabecular architecture) is vital if we are to understand bone maintenance and fragility in the past.

Management of Low Bone Mineral Density in Premenopausal Women

OBJECTIVE

To review evidence for management of low bone density in premenopausal women and to establish practical guidelines for management of low bone density in this population by family physicians.

METHOD

A search of MEDLINE for relevant articles published between January 1990 and May 2004 was conducted. Articles retrieved were graded by level of evidence. Recommendations for diagnosis and therapy were based on evidence from randomized controlled trials and expert consensus.

RESULTS

Low bone density in premenopausal women is not associated with the same increased risk of fracture seen in older women. In the absence of fragility fractures and loss of height, it may be a reflection of low peak bone mass and may represent the normal variation in bone mineral density (BMD). Women may have low bone density secondary to an underlying skeletal or systemic disorder. Common causes of low bone density in premenopausal women include ovulatory disturbances and low body weight.

CONCLUSION

Osteoporosis is diagnosed in the premenopausal female population in the presence of fragility fractures and is not based solely on the results of BMD testing. Secondary causes of bone loss should be excluded, and any underlying condition contributing to low bone density should be corrected. Antiresorptive therapy has been evaluated only in those premenopausal women who are on glucocorticoid therapy and in those with primary hyperparathyroidism. Only in these conditions has antiresorptive therapy been shown to improve BMD.

Maternity and bone mineral density

During pregnancy and lactation, changes occur in a variety of factors which have great potential to influence bone mineral density (BMD). Smoking habits, the level of alcohol consumption, the level of physical activity, body weight, soft tissue composition and hormone levels are all factors that change during the course of these conditions. Some of these factors are capable of increasing BMD, and some can reduce it. Due to these various changes, it is virtually impossible to predict the development in BMD that will occur during a pregnancy and lactation. However, longitudinal studies have suggested that both pregnancy and lactation are associated with a BMD loss of up to 5%, albeit that the BMD recovers after weaning. Cross-sectional studies have indicated that women with many children and a long total period of lactation have similar or higher BMD and similar or lower fracture risk than their peers who have not given birth. As the studies showing this trend have been observational and cross sectional case-control studies, the conclusions can only be regarded as being suggestive, and no causality can be proven.

Smoking and fracture risk: a meta-analysis

Smoking is widely considered a risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the relationship of this risk with age, sex and bone mineral density (BMD). We studied 59,232 men and women (74% female) from ten prospective cohorts comprising EVOS/EPOS, DOES, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, Hiroshima and two cohorts from Gothenburg. Cohorts were followed for a total of 250,000 person-years. The effect of current or past smoking, on the risk of any fracture, any osteoporotic fracture and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age, sex and BMD. The results of the different studies were merged using the weighted beta-coefficients. Current smoking was associated with a significantly increased risk of any fracture compared to non-smokers (RR=1.25; 95% Confidence Interval (CI)=1.15-1.36). Risk ratio (RR) was adjusted marginally downward when account was taken of BMD, but it remained significantly increased (RR=1.13). For an osteoporotic fracture, the risk was marginally higher (RR=1.29; 95% CI=1.13-1.28). The highest risk was observed for hip fracture (RR=1.84; 95% CI=1.52-2.22), but this was also somewhat lower after adjustment for BMD (RR=1.60; 95% CI=1.27-2.02). Risk ratios were significantly higher in men than in women for all fractures and for osteoporotic fractures, but not for hip fracture. Low BMD accounted for only 23% of the smoking-related risk of hip fracture. Adjustment for body mass index had a small downward effect on risk for all fracture outcomes. For osteoporotic fracture, the risk ratio increased with age, but decreased with age for hip fracture. A smoking history was associated with a significantly increased risk of fracture compared with individuals with no smoking history, but the risk ratios were lower than for current smoking. We conclude that a history of smoking results in fracture risk that is substantially greater than that explained by measurement of BMD. Its validation on an international basis permits the use of this risk factor in case finding strategies.

Predictors of bone mineral density in female workers in Morelos State, Mexico

BACKGROUND

Although several studies have identified factors associated with bone mineral density (BMD), little research is available on Mexican women.

METHODS

A cross-sectional study was conducted in 1,622 female workers between 20 and 80 years of age at the Mexican Social Security Institute (IMSS), an integral part of the Mexican health system. It was carried out in Morelos, a Mexican state that borders Mexico City. Women were recruited to participate in this study from their workplaces. Body mass index (BMI) was measured and BMD was assessed using dual-energy x-ray absorptiometry of dominant forearm. Predictors of BMD (age, reproductive factors, BMI, diet, and physical activity) in pre- and postmenopausal women were assessed by questionnaire and analyzed using generalized additive models.

RESULTS

In premenopausal women, older age, higher BMI, younger age at menarche, and greater vitamin D intake were associated with higher BMD (R(2)=0.06, null deviance reduction=6.9%). In postmenopausal women, determinants of BMD were older age, higher BMI, greater height, later initiation of menopause, longer time of use of hormonal replacement therapy (HRT), and greater calcium intake from dairy products (R(2)=0.39, null deviance reduction=40.7%).

CONCLUSIONS

As observed in other populations, age, BMI, height, age at menopause, time of use of HRT, and calcium intake derived from dairy products in these Mexican women are factors associated with higher forearm BMD during postmenopausal period. Age, BMI, age at menarche, and vitamin D are associated with higher forearm BMD in premenopausal women. Some of these factors are not linearly associated with BMD. This was a limited population study carried out in a large group of female healthcare workers whose reproductive and lifestyle factors potentially agreed with those of female workers from urban areas of Mexico.

Bone densitometry in premenopausal women: synthesis and review

Bone loss prior to menopause is being increasingly identified in women. Clearly, low bone mineral density (BMD) is a significant risk factor for fracture in the estrogen-deficient female postmenopause. The significance of low bone density prior to menopause needs to be addressed. Low bone density in the premenopausal female may reflect attainment of a lower peak bone mass. It may also be secondary to progressive bone loss following achievement of peak bone density. The etiology of low bone density in the premenopausal female needs to be clarified with meticulous exclusion of secondary causes of bone loss. Menstrual status is an important determinant of peak bone mass as well as the development of bone loss in women prior to the onset of menopause. Subclinical decreases in circulating gonadal steroids may be associated with a lower peak bone mass as well as progressive bone loss in otherwise reproductively normal women. Elevations of follicle-stimulating hormone (FSH) of greater than 20 miu/L are associated with evidence of increased bone turnover marker activity and correlate with progressive bone loss in perimenopausal women. This transitional period requires further study with respect to the magnitude of bone loss experienced and the potential benefits of antiresorptive therapy. Detailed assessment of menstrual status is necessary in the evaluation of low bone density in premenopausal women. The majority of the cross-sectional and longitudinal studies completed evaluating BMD in the premenopausal years suggest that minimal bone loss does occur prior to menopause after attainment of peak bone mass. The magnitude of premenopausal bone loss, however, is controversial and may be site-dependent. More rapid rates of bone loss are seen in the transitional period beginning 2-3 yr prior to the onset of menopause. Prospective data are needed to understand further the relationship between BMD and fracture in the premenopausal period. Women with steroid-induced bone loss as well as other secondary causes of osteoporosis respond to antiresorptive therapy with documented improvements in BMD. Biomarkers can identify perimenopausal women with increased bone turnover. Lifestyle modification can improve BMD in the pre- and the perimenopausal period. Antiresorptive therapy has not been evaluated in pre- or perimenopausal women with low BMD in the absence of secondary causes of osteoporosis. As new treatment options are evaluated and become available, biomarker assessment may be of value in identifying women at risk of fracture.

Endogenous hormones and bone turnover markers in pre- and perimenopausal women: SWAN

We tested the hypothesis that higher serum osteocalcin and urinary N-telopeptide of type I collagen (NTx) concentrations would be found in women with increasing cycle irregularity or increased follicle stimulating hormone concentrations. We studied 2,375 pre- and early perimenopausal women from the Study of Women's Health Across the Nation (SWAN), aged 42-52 years, who self-identified their race/ethnic origin as African-American (28.3%), Caucasian (49.4%), Japanese (10.5%) or Chinese (11.8%). Outcome measures were serum osteocalcin, a measure of bone formation, and NTx, a measure of bone resorption. The explanatory variables were menopausal status, based on self-reported regularity of menstrual bleeding, and circulating endogenous hormone concentrations including estradiol (E(2)), testosterone (T), sex hormone binding globulin (SHBG) and follicle stimulating hormone (FSH) concentrations. Additionally, we evaluated the association of the bone turnover markers with the Free Androgen Index (FAI) and the Free Estradiol Index (FEI), ratios of total testosterone and estradiol concentrations to SHBG, respectively. Higher FSH concentrations were associated with higher NTx concentrations ( beta=0.003, partial r2=2.1%, p<0.0001), both before and after adjusting for other covariates (total explained variability of 9%). Higher FSH concentrations were also associated with higher osteocalcin concentrations ( beta=-0.216, partial r2=4.1%, p<0.0001, total explained variability of 15.4%). There were no significant associations of the bone turnover markers with other endogenous hormones, following adjustment for covariates. Mean osteocalcin and NTx values were not significantly different in premenopausal women compared to early perimenopausal women. In these pre- and early perimenopausal women, higher FSH concentrations, but not other serum reproductive hormone concentrations, are positively associated with greater bone turnover prior to the last menstrual period.

A 2-year prospective study on the effects of depot medroxyprogesterone acetate on bone mass-response to estrogen and calcium therapy in individual users

The primary aim of this prospective 2-year follow-up study was to investigate the effect of depot medroxyprogesterone acetate (DMPA) on the maintenance of bone mass in women aged 30-45 years. The effects of estrogen or calcium substitution during the second year of follow-up was investigated in seven DMPA users with a high annual bone loss during the first year. The bone mass of 35 users of DMPA and 10 women without hormonal contraception was investigated using peripheral quantitative computed tomography. The baseline cortical and trabecular bone mass (TBM) and the annual change was not different in DMPA users and controls. Over 24 months we measured an increase in TBM of 0.6% and a decrease in cortical bone mass of 0.1% in exposed women. Some but not all of the DMPA users with a bone loss during the first year could be successfully treated with estradiol or calcium. In conclusion, we did not observe an accelerated bone loss in DMPA users aged 30-45 years.

Discrepant areal and volumetric bone density measurements in a young woman with idiopathic low bone mineral density

OBJECTIVE

To discuss a case of idiopathic low bone density in a young woman.

METHODS

We present a detailed report that includes clinical, laboratory, and radiologic assessment of a pre-menopausal woman with idiopathic low bone mass.

RESULTS

A 34-year-old healthy woman of small body habitus was found by dual-energy x-ray absorptiometry to have bone mineral density (BMD) that was less than 2.5 standard deviations below the young and age-matched norm. After a thorough evaluation, no cause of osteoporosis was identified. Calculation of bone mineral apparent density, which minimizes the effect of small skeletal size on areal BMD, resulted in only a modest improvement in T-scores. Measurement of lumbar spine volumetric BMD by quantitative computed tomography, however, revealed a significantly improved T-score of -1.6.

CONCLUSION

This report highlights the complexities of low BMD measurements in otherwise healthy young women as well as the potential application of bone mineral apparent density and quantitative computed tomography in the evaluation of low BMD in young women with small skeletal frames.

Bone mineral density in young women of the city of São Paulo, Brazil: correlation with both collagen type I alpha 1 gene polymorphism and clinical aspects

Osteoporosis is a multifactorial disease with great impact on morbidity and mortality mainly in postmenopausal women. Although it is recognized that factors related to life-style and habits may influence bone mass formation leading to greater or lower bone mass, more than 85% of the variation in bone mineral density (BMD) is genetically determined. The collagen type I alpha 1 (COLIA1) gene is a possible risk factor for osteoporosis. We studied a population of 220 young women from the city of São Paulo, Brazil, with respect to BMD and its correlation with both COLIA1 genotype and clinical aspects. The distribution of COLIA1 genotype SS, Ss and ss in the population studied was 73.6, 24.1 and 2.3%, respectively. No association between these genotypes and femoral or lumbar spine BMD was detected. There was a positive association between lumbar spine BMD and weight (P<0.0001), height (P<0.0156), and body mass index (BMI) (P<0.0156), and a negative association with age at menarche (P<0.0026). There was also a positive association between femoral BMD and weight (P<0.0001), height (P<0.0001), and BMI (P<0.0001), and a negative correlation with family history for osteoporosis (P<0.041). There was no association between the presence of allele s and reduced BMD. We conclude that a family history of osteoporosis and age at menarche are factors that may influence bone mass in our population.

The effects of menstrual and menopausal factors on bone mineral content in healthy Polish women

The aims of the study were the following: (1) An evaluation of which factor, aging itself or the occurence of menopause, revealed a more detrimental effect on bone mineral content (BMC) of healthy women; (2) An assesment of influence of other factors (the menarcheal age, the total number of reproductive years and the lenght of the period after menopause) on BMC. Our sample material comprised a group of 928 healthy females (715 pre- and 213 postmenopausal), aged 20-62. BMC at the ultra-distal radius was assessed by pQCT. BMC differences between particular groups were tested using a two-way ANOVA. The menopause was related to BMC decline and the impact of menopausal hormonal alterations was much stronger than that of chronological age. Among postmenopausal women, the total number of reproductive years was not an independent predictor of better bone status. In premenpausal women the beneficial effect of earlier menarche on bone tissue is maintained.

Familial resemblance of bone mineral density between females 18 years and older and their mothers

Potential determinants of bone mass were investigated in a group of 70 young females (mean age 26.6 years), daughters of women studied in premenopause. Nutritional data, leisure physical activity level, lifestyle habits as well as familial similarities were assessed. The daughters' bone mineral density (BMD), measured by dual-energy absorptiometry, was significantly correlated with their body mass index (BMI) (r = 0.22), dietary vitamin D intake (r = 0.19) and their mothers' BMD (r = 0.44). Multiple regression analysis indicated that only the mothers' BMD remained an independent predictor of bone mass. Mother-daughter correlations were also observed for body weight (r = 0.24), height (r = 0.39), BMI (r = 0.29), dietary calcium intake (r = 0.20), and calcium (r = 0.20) or vitamin D (r = 0.25) intakes from dairy products. Hence, these observations support the evidence that mothers' BMD is the strongest predictor of bone mass of young women in their third decade.

The relation between lifestyle factors and biochemical markers of bone turnover among early postmenopausal women

We examined the associations of two biochemical markers of bone turnover with lifestyle factors in 340 postmenopausal women in Hawaii, ages 45-59 years, from the Early Postmenopausal Intervention Cohort. Physical activity, calcium supplement use, smoking and alcohol use in the prior 2 weeks were measured and examined as independent variables in multiple regression analyses with bone turnover markers as dependent variables, adjusted for weight, height, whole body bone mass, serum estradiol, years since menopause, and ethnicity. Calcium supplement and alcohol use were significantly associated with reduced levels of urinary type I collagen cross-linked N-telopeptides (NTX). The mean NTX level was 12% lower among women using > or = 250 mg of calcium supplements per day as compared with other women, and 20% lower among alcohol users compared with nonusers. Both calcium supplement use and alcohol intake were associated with lower mean serum osteocalcin (a marker of bone formation) and NTX z-scores. By contrast, smoking was associated with lower osteocalcin levels, without any effect on NTX. The osteocalcin level was 12% lower among smokers compared with nonsmokers. In addition, the z-score difference between NTX and osteocalcin was significantly associated with smoking, with a shift towards more NTX than osteocalcin. Physical activity was not significantly associated with either of the markers. These findings suggest that biochemical markers may help to identify lifestyle factors that affect bone, and provide estimates of the relative magnitude of these effects on bone formation and resorption, independent of each other.

Sex steroids and bone

Sex steroids are essential for skeletal development and the maintenance of bone health throughout adult life, and estrogen deficiency at menopause is a major pathogenetic factor in the development of osteoporosis in postmenopausal women. The mechanisms by which the skeletal effects of sex steroids are mediated remain incompletely understood, but in recent years there have been considerable advances in our knowledge of how estrogens and, to a lesser extent androgens, influence bone modeling and remodeling in health and disease. New insights into estrogen receptor structure and function, recent discoveries about the development and activity of osteoclasts, and lessons learned from human and animal genetic mutations have all contributed to increased understanding of the skeletal effects of estrogen, both in males and females. Studies of untreated and treated osteoporosis in postmenopausal women have also contributed to this knowledge and have provided unequivocal evidence for the potential of high-dose estrogen therapy to have anabolic skeletal effects. The development of selective estrogen receptor modulators has provided a new approach to the prevention of osteoporosis and other major diseases of menopause and has implications for the therapeutic use of other steroid hormones, including androgens. Further elucidation of the mechanisms by which sex steroids affect bone thus has the potential to improve the clinical management not only of osteoporosis, both in men and women, but also of a number of other diseases related to sex hormone status.

Exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDT) in relation to bone mineral density and rate of bone loss in menopausal women

The organochlorine pesticide 2,2-bis(p-chlorophenyl)-1,1,1,-trichloroethane (DDT) and its metabolite 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) are examples of an environmental contaminant that may have hormonal properties. Bone metabolism is both estrogen- and androgen-dependent. Exposures to various environmental endocrine disrupters can affect bone metabolism in animals, but there are no published data concerning the effect of DDE exposure on bone metabolism in humans. We hypothesized that high levels of DDE would be associated with lower bone density in peri- and postmenopausal women than in premenopausal women. Study subjects were drawn from the cohort of women who had participated in the Mount Sinai Medical Center Longitudinal Normative Bone Density Study (1984-1987). We used serum samples obtained at study entry to measure DDE levels in 103 (50 black, 53 white) women (mean age = 54.5 y [standard deviation = 5 y]). Measurements of bone mineral density at the lumbar spine and radius were made at 6-mo intervals during a 2-y period. DDE concentrations were significantly (p < .001) higher in blacks (13.9 ng/ml) than in whites (8.4 ng/ml), but there was no correlation between DDE concentration and bone density at the spine (mean levels = 1.065 g/cm2 and 1.043 g/cm2 in the lowest and highest quartiles, respectively, of DDE [trend p value = .85]) or at the radius (mean levels = 0.658 g/cm and 0.664 g/cm in the lowest and highest quartiles, respectively, of DDE [trend p value = .34]). Longitudinal analyses revealed no correlation between DDE and the rate of bone loss at either bone site. Similar results were seen in race-stratified analyses, as well as in analyses in which we controlled for lactation history and other potential confounders. We found little evidence that chronic low-level DDT exposure is associated with bone density in peri- and postmenopausal women.

Is caffeine associated with bone mineral density in young adult women?

BACKGROUND

By increasing the urinary excretion of calcium, caffeine consumption may reduce bone mineral density (BMD) and subsequently increase the risk for osteoporotic fracture. Although negative associations between caffeine consumption and BMD have been reported for postmenopausal women, in particular for those who consume low amounts of dietary calcium, the relation between caffeine and BMD in younger women is unclear. Therefore, we evaluated the association between caffeine consumption and BMD in a cross-sectional study of 177 healthy white women, age 19-26 years, who attended a Midwestern university.

METHODS

Average caffeine intake (milligrams per day) was calculated from self-reports of the consumption of coffee, decaffeinated coffee, tea, colas, chocolate products, and select medications during the previous 12 months (mean caffeine intake = 99. 9 mg/day). BMD (grams per square centimeter) at the femoral neck and the lumbar spine was measured by dual-energy X-ray absorptiometry.

RESULTS

After adjusting in linear regression models for potential confounders, including height, body mass index, age at menarche, calcium intake, protein consumption, alcohol consumption, and tobacco use, caffeine consumption was not a significant predictor of BMD. For every 100 mg of caffeine consumed, femoral neck BMD decreased 0.0069 g/cm(2) (95% confidence in terval [CI] = -0.0215, 0. 0076) and lumbar spine BMD decreased 0.0119 g/cm(2) (95% CI = -0. 0271, 0.0033). No single source of caffeine was significantly associated with a decrease in BMD. Furthermore, the association between caffeine consumption and BMD at either site did not differ significantly between those who consumed low levels of calcium (< or =836 mg/day) and those who consumed high levels of calcium (>836 mg/day).

CONCLUSIONS

Caffeine intake in the range consumed by young adult women is not an important risk factor for low BMD.

Oral contraceptive use by teenage women does not affect peak bone mass: a longitudinal study

OBJECTIVE

To determine the effect of oral contraceptive pill (OCP) use during adolescence on peak bone mass.

DESIGN

Longitudinal observational study.

SETTING

Academic clinical research center.

PATIENT(S)

Sixty-two non-Hispanic, white females in The Penn State Young Women's Health Study, who were studied for 8 years during ages 12-20.

INTERVENTION(S)

There were 28 OCP users, who used OCPs for a minimum of 6 months and were still using at age 20, and 34 nonusers who had never used OCPs.

MAIN OUTCOME MEASURE(S)

Total body bone, dedicated hip bone, and body composition measurements were made by dual-energy roentgenogram absorptiometry.

RESULT(S)

The OCP users and nonusers did not differ at entry in anthropometric, body composition, or total body bone measurements. By age 20, the average duration of OCP use by the user group was 22 months. At age 20, the groups remained indistinguishable in anthropometric, body composition, total body, and hip bone measures, and in age of menarche and sports exercise scores.

CONCLUSION(S)

Oral contraceptive pill use by healthy, white, teenage females does not affect acquisition of peak bone mass.

Gynecological factors and body mass index as determinants of bone mass in normal postmenopausal women. A study with peripheral quantitative computed tomography (pQCT)

OBJECTIVE

This paper studied the influence of several gynecological factors (years since menopause (YSM), age at menarche and gynecological age or reproductive life) simultaneously with anthropometric factors as determinants of bone mass in 189 healthy postmenopausal women.

METHODS

Bone mass was determined by peripheral quantitative computed tomography.

RESULTS

An overall evaluation showed that YSM correlated negatively with trabecular and cortical bone density (BMDTrab and BMDCorti) (P<0.05 in both cases). Age at menarche correlated negatively with BMDCorti (P<0.05) and gynecological age correlated positively with BMDTrab (P<0.05). Classifying the women according to their body mass index (BMI), the YSM correlation persisted in those subjects whose BMI was >25 kg/m(2), and in age at menarche and gynecological age of women whose BMI was <25 kg/m(2) (P<0.05). After separating women according to their age at menarche, their gynecological age and BMI, the only significant difference that persisted was in BMDTrab which was lower in the group with gynecological age <33 years, with a BMI <25 kg/m(2) (P=0.020). Parity and smoking had no impact on our results. By multiple regression, with BMD as the dependent variable and the gynecological factors as independent variables, we only observed significance between YSM and BMDCorti (P<0.005). The same was observed after separating women according to their BMI in the >25 kg/m(2) group (P<0.05).

CONCLUSIONS

Our data stress the importance of YSM on BMDTrab and BMDCorti, of age at menarche on BMDCorti and of gynecological age on BMDTrab. However, YSM is the gynecological factor that mainly determines BMD. The differences observed between measurements taken with pQCT and other methods commonly used to estimate bone mass indicate that results obtained with one technique cannot be extrapolated to other methods.

Age-dependent cortical bone loss in women from 18th and early 19th century London

Age-dependent cortical bone loss was investigated in an earlier British population. The study sample comprised female skeletons from the 18th/19th century crypt at Christ Church, Spitalfields, London. Bone loss was monitored using metacarpal radiogrammetry. Age at death was known exactly from coffin plates. Results indicated that peak cortical thickness was less than in modern subjects. Continuing periosteal apposition was evident throughout adulthood, and the rate of increase in metacarpal diameter resembled that in modern subjects. Bone loss from the endosteal surface was evident from the fifth decade onwards, and this outstripped the rate of subperiosteal gain so that there was a net loss of cortical bone with age. Cortical bone loss occurred at a similar rate to that in modern subjects. In contrast to modern populations, there was no evidence that loss of cortical bone was associated with increased propensity to fracture. The present results, together with those previously published for a British medieval skeletal assemblage, suggest that patterns of cortical bone loss in women have remained unchanged over at least the last millennium in Britain. Given the great changes in lifestyle which have occurred during this period, this suggests that lifestyle factors may be rather less important than is sometimes asserted in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned.

A prospective study on the effects of depot medroxyprogesterone acetate on trabecular and cortical bone after attainment of peak bone mass

OBJECTIVE

To study the annual change of bone mass in women aged 30-45 years being treated with depot medroxyprogesterone acetate (DMPA) in order to evaluate whether the bone mass depends on the duration of DMPA use or the oestradiol level.

DESIGN

Prospective longitudinal study over an interval of 12 months.

SETTING

A family planning centre of a university hospital.

PATIENTS

Thirty-six current users of DMPA.

INTERVENTIONS

Injection of 150 mg DMPA every 12 weeks.

MEASUREMENTS

Bone mass was measured at the distal radius by peripheral quantitative computed tomography (reproducibility 0.3%).

RESULTS

Mean annual changes (SD) in trabecular and cortical bone mass were 0.06 (1.6%) [P = 0.8] and -0.26% (0.6) [P < 0.04]. The decrease in cortical bone mass was not significant because the changes were within the precision error of the method used for the measurements. Duration of DMPA use and oestradiol levels were not associated to the bone parameters.

CONCLUSION

We did not find a negative impact of DMPA on the bone mass of premenopausal women aged 30-45 years.