Bone mass and metabolism in women aged 45-55

Independent Skeletal Actions of Pituitary Hormones

Over the past years, pituitary hormones and their receptors have been shown to have non-traditional actions that allow them to bypass the hypothalamus-pituitary-effector glands axis. Bone cells-osteoblasts and osteoclasts-express receptors for growth hormone, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin, and vasopressin. Independent skeletal actions of pituitary hormones on bone have been studied using genetically modified mice with haploinsufficiency and by activating or inactivating the receptors pharmacologically, without altering systemic effector hormone levels. On another front, the discovery of a TSH variant (TSH-βv) in immune cells in the bone marrow and skeletal action of FSHβ through tumor necrosis factor α provides new insights underscoring the integrated physiology of bone-immune-endocrine axis. Here we discuss the interaction of each pituitary hormone with bone and the potential it holds in understanding bone physiology and as a therapeutic target.

Evaluation of Thyroid Hormone Status and Bone Density Ratio in Euthyroid Postmenopausal Women in Early and Late Stage of Bone Loss

Introduction:

Osteoporosis is a consequence of reduction in bone mass and disorders of bone structure, which makes the bones prone to fractures. Physiological variations of thyroid-stimulating hormone (TSH) may be an early indicator of the predisposing basis of the emergence of osteoporosis.

Aim:

To evaluate the thyroid hormone status and bone density ratio in euthyroid postmenopausal women in early and late stage of bone loss.

Methods:

The research is an observational, intersected, controlled study involving postmenopausal women admitted to the Clinic for Nuclear medicine and endocrinology of the Clinical Center University of Sarajevo (CCUS). The study included a total of 120 postmenopausal subjects divided into two groups. First group included 60 postmenopausal patients with osteoporosis, 30 of them were at the early stage of postmenopause, and 30 were in the late postmenopausal phase. The second group consisted of 60 postmenopausal patients with preserved bone mass, 30 of which were in the early stage of postmenopause and 30 in the late postmenopausal phase. For all patients included in the study follicle-stimulating hormone (FSH), TSH, free thyroxine (FT4), free triiodothyronine (FT3) were analyzed.

Results:

The mean duration of the postmenopausal period was statistically significantly higher in the group of women with osteoporosis (11.4 ± 1.1 years). The mean values of FSH were statistically significantly higher in the group of women with osteoporosis (54.0 ± 2.6 IU / L). The mean level of TSH and FT3 did not statistically significantly differ in the group of women with osteoporosis compared to the control group of women. The mean FT4 level in women with osteoporosis was statistically significantly lower (14.7 ± 0.29 pmol / L) compared to the control group of women (15.95 ± 0.3 pmol / L) (p = 0.004).

Conclusion:

In our examined group, the FT4 patient (mean) was significantly lower in the serum of women with osteoporosis compared to subjects with preserved bone mass. It would be most effective to recognize risk factors in order to influence them on time, and to alleviate and slow down the consequences of osteoporosis. One of these possible factors is the hormonal status of the thyroid gland, that is, TSH whose physiological variations may be an early indicator of the predisposing basis for the emergence of osteoporosis. The frequency and prevalence of these medical problems require additional research, and it is also a great challenge to understand the effects of thyroid hormone on bone tissue.

The Relationship between Follicle-stimulating Hormone and Bone Health: Alternative Explanation for Bone Loss beyond Oestrogen?

Bone loss in women commences before the onset of menopause and oestrogen deficiency. The increase of follicle-stimulating hormone (FSH) precedes oestrogen decline and may be a cause for bone loss before menopause. This review summarizes the current evidence on the relationship between FSH and bone derived from cellular, animal and human studies. Cellular studies found that FSH receptor (FSHR) was present on osteoclasts, osteoclast precursors and mesenchymal stem cells but not osteoblasts. FSH promoted osteoclast differentiation, activity and survival but exerted negligible effects on osteoblasts. Transgenic FSHR or FSH knockout rodents showed heterogenous skeletal phenotypes. Supplementation of FSH enhanced bone deterioration and blocking of FSH action protected bone of rodents. Human epidemiological studies revealed a negative relationship between FSH and bone health in perimenopausal women and elderly men but the association was attenuated in postmenopausal women. In conclusion, FSH may have a direct action on bone health independent of oestrogen by enhancing bone resorption. Its effects may be attenuated in the presence of overt sex hormone deficiency. More longitudinal studies pertaining to the effects of FSH on bone health, especially on fracture risk, should be conducted to validate this speculation.

Association between dietary calcium and phosphorus intakes, dietary calcium/phosphorus ratio and bone mass in the Korean population

BACKGROUND

Osteoporosis has become a major public health issue. Among various factors affected bone health, not only dietary calcium and phosphorus intakes, but also the dietary calcium/phosphorus ratio could relate to bone health. Therefore, we evaluated whether dietary calcium and phosphorus intakes, and dietary calcium/phosphorus ratio are associated with bone mass in Korean adults ≥ 20 years of age.

METHODS

The analysis used data from the Korean National Health and Nutrition Examination Survey, a cross-sectional survey of Korean civilians, conducted from January to December 2010. A total of 4,935 participants (2,309 men and 2,626 women) were analyzed in this study. Dietary calcium and phosphorus intakes of the participants were estimated using 24-h dietary recall. Bone mass densities for the whole body, femoral neck, and lumbar spine were measured by dual-energy X-ray absorptiometry.

RESULTS

Dietary calcium intake and dietary calcium/phosphorus ratio were positively related to bone mass density for femoral neck in men ≥ 50 years of age (p = 0.046 and 0.041, respectively). Dietary calcium intake showed positive associations with bone mass density for whole body in premenopausal women (p = 0.022).

CONCLUSIONS

Increased calcium intake and high dietary calcium/phosphorus ratio might have favorable effects on bone mass in Korean adults. Additional gender- and age-specific studies are needed to further identify the influence of calcium and phosphorus intakes, and the dietary calcium/phosphorus ratio on bone mass.

Enhancement of calcium/vitamin d supplement efficacy by administering concomitantly three key nutrients essential to bone collagen matrix for the treatment of osteopenia in middle-aged women: a one-year follow-up

Two vitamins and proline (CB₆Pro), three nutrients essential for bone collagen, were used in combination to a 1000 mg calcium/250 IU vitamin D (Ca/D) daily supplement to treat osteopenia as a preventive measure against osteoporosis later in life. Middle-aged women not using estrogen were screened for osteopenia using the WHO criteria and divided into three groups (n = 20 each): 1) placebo healthy controls with normal bone mineral density (BMD); 2) control Ca/D-treated osteopenic patients; and 3) Ca/D + CB₆Pro-treated osteopenic patients. The three groups were comparable at baseline except for BMD. After one-year treatment, cortical diaphyseal BMD remained constant in each group, but trabecular bone loss persisted (at 5 lumbar sites) in osteopenic group 2. No further bone loss was detected in osteopenic group 3. A loss of 2% was evidenced in the placebo group at one lumbar site. Markers of bone formation (which increase in coupling to resorption) decreased significantly in both osteopenic groups. Although biomarkers of resorption did not change, hormone (PTH and 1,25(OH)₂D₃)-induced osteoclastic activity was significantly reduced. No decline in BMD occurred at any bone site in osteopenic group 3, highlighting the importance of improving the quality of bone matrix concomitantly to mineral replacement.

Bone Mineral Density and Metabolism at an Early Stage of Menopause When Estrogen and Calcium Supplement Are Not Used and without the Interference of Major Confounding Variables

OBJECTIVES

To measure bone mineral density (BMD) and to screen for early biochemical abnormalities in bone mineral metabolism in the first five years of natural menopause when estrogen and calcium supplement are not used and in the absence of major confounding variables.

SETTING

Two homogeneous and comparable groups (n = 30) of healthy pre- and postmenopausal Caucasian women living in a northern region (latitude 46 degrees N) were recruited during the mid-Spring/Summer season in a cross-sectional design.

METHODS

Volumetric apparent BMAD (g/cm(3)) was calculated from areal BMD (g/cm(2)) which was evaluated by dual energy X-ray absorptiometry (Lunar) at both axial and peripheric (femur) sites using two sets of reference values (WHO criterion expressed as T-score and absolute values of areal density) in combination to bone specific biochemical measurements.

RESULTS

BMD and BM(A)D were significantly lower in postmenopausal women for all lumbar sites, but not for Ward's triangle and any other femoral sites whereas free deoxypyridinoline (Dpd), urinary biochemical marker of bone resorption, was markedly (p < 0.0001) greater. Their serum calcium and phosphate were significantly higher without a difference in 1,25(OH)(2)D(3) and PTH. The prevalence of osteopenia in pre- and postmenopausal women was about 2-fold lower in both groups (26.6 and 46.9%, respectively) when lumbar (L) spine and femur neck were combined and using the criteria based on reference values of areal density instead of T-scores.

CONCLUSIONS

The present study showed that the negative effects of estrogen deficiency on BMD and bone metabolism in early menopause occurred independently of the effect of major calcitropic hormones. Bone loss affects a non negligible proportion of premenopausal women. The prevalence of osteopenia in pre- and postmenopausal women varied according to the criterion used and anatomic site.

B-6 vitamers and 4-pyridoxic acid in the plasma, erythrocytes, and urine of postmenopausal women

BACKGROUND

Although many studies have reported reduced vitamin B-6 status with aging, little information is available about the specific effects of menopause.

OBJECTIVE

We aimed to examine vitamin B-6 metabolism in premenopausal and early postmenopausal women.

DESIGN

We examined dietary intake and vitamin B-6 metabolites in the plasma, erythrocytes, and urine of 30 premenopausal women (x +/- SD age: 41.9 +/- 4.8 y) and 30 women (aged 54.0 +/- 3.8 y) who were 4.0 +/- 1.4 y past menopause.

RESULTS

Vitamin B-6 intake in the postmenopausal group (1.97 +/- 0.40 mg/d) was significantly greater than that in the premenopausal group (1.63 +/- 0.50 mg/d). Plasma pyridoxal phosphate (PLP) and pyridoxal concentrations and erythrocyte PLP, pyridoxal, and pyridoxamine phosphate concentrations were in the normal range in both groups and did not differ significantly between the 2 groups. Plasma and erythrocyte 4-pyridoxic acid (4-PA) concentrations were significantly higher in the postmenopausal group than in the premenopausal group, which may have been due at least partly to the slightly higher vitamin B-6 intake of the former group. Erythrocyte 4-PA was correlated (r = -0.37, P < 0.01) with serum estradiol in both groups. Urinary 4-PA did not differ significantly between the 2 groups. The serum phosphate concentration was higher in the postmenopausal group than in the premenopausal group, and it was correlated (r = 0.40, P < 0.01) with plasma PLP. Inhibition of alkaline phosphatase by the increased phosphate may help to increase plasma PLP.

CONCLUSION

Menopause may not necessarily be associated with a decrease in vitamin B-6 status.

Variation in menstrual cycle length and cessation of menstruation in captive raised baboons

Primatologists have recognized that non-humans undergo the menopause [Biol. Reprod. 68 (2003) 10], which is preceded by years of irregular cycles and decreased fecundity. The similarity of reproductive changes between humans and baboons suggests that the aging female baboon is a particularly promising model to study human menopause and changes that precede it. In an effort to provide an assessment of potential peri-menopausal changes in reproductive function in non-human primates, our goals were to determine if menstrual cycles become more variable with age and to identify the onset of changes consistent with peri-menopause and menopause in baboons. To accomplish these goals, we calculated means and variances for menstrual cycle lengths of females at ages 5, 10, 15, and 20 years and identified onset of menstrual cycle variability (peri-menopause) and cessation of menstruation (menopause). Mean cycle lengths were not significantly different, but significant heterogeneity of variances existed, with younger animals experiencing less variability than older animals. Mean ages of onset for the peri- and menopausal transitions were 18.89 and 26.34 years, respectively. These results provide evidence that captive aging female baboons experience menstrual cycle changes similar to peri- and menopausal women.

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.

Follicle stimulating hormone measured in unextracted urine throughout the menstrual cycle correlates with age and ovarian reserve

BACKGROUND

A method was previously described to measure FSH reliably in unextracted urine. The aim of the current study was to establish the course of FSH measured in urine throughout the cycle.

METHOD

Daily urinary FSH (uFSH) concentrations were determined in 14 regularly menstruating volunteers aged 23-39 years during one complete menstrual cycle.

RESULTS

In each subject, mean daily uFSH measured in urine, as gold standard for FSH tone, correlated significantly with FSH in early follicular phase fixed to menstruation on cycle day 3 (r = 0.75, P = 0.002), or fixed to ovulation 9 days before the pre-ovulatory FSH surge (r = 0.87, P = 0.0001), or when selected as being the highest follicular phase value (r = 0.91, P = 0.0001). Age correlated significantly with mean daily uFSH (r = 0.67, P = 0.009), highest follicular phase uFSH (r = 0.60, P = 0.024), uFSH on cycle day 3 (r = 0.80, P = 0.0006), and uFSH 9 days before FSH surge (r = 0.65, P = 0.0016). The uFSH was also measured on cycle day 3 in 104 IVF patients in a cycle prior to pituitary down-regulation. The uFSH correlated significantly with numbers of follicles (P = 0.02) and oocytes (P = 0.024).

CONCLUSION

It is concluded that cycle day 3 uFSH is a good reflection of the mean uFSH of the complete cycle, and there is a highly significant correlation between uFSH and age and ovarian reserve. Measurement of FSH in urine on cycle day 3 seems to be a reliable and non-invasive tool for determining ovarian reserve in IVF.

Concentrations of follicle-stimulating hormone correlate with alkaline phosphatase and a marker for vitamin K status in the perimenopause

Serum alkaline phosphatase (ALP), a gross marker of bone turnover, has been reported to be elevated after menopause, a period characterized by hallmark increases in follicle-stimulating hormone (FSH). Whether the ALP rise coincides with the perimenopausal transition when changes in FSH, estrogen levels, and menstrual cycles are first apparent is not known. The purpose of this cross-sectional study was twofold: (1) to characterize the influence of the perimenopausal transition on ALP activity and (2) to correlate ALP activity with more precise markers for bone, osteocalcin (OC), and vitamin K status assessed with undercarboxylated osteocalcin (ucOC). Thirty-eight studies of hourly FSH were conducted on cycle day 6 of the follicular phase in perimenopausal women volunteers, aged 40-54 years (mean body mass index [BMI] = 24.2 +/- 0.5). Mean FSH was used to define the perimenopausal stage (early perimenopausal, mean FSH </= 15 IU/L, n = 27; late perimenopausal, mean FSH > 15 IU/L, n = 11). As expected, late perimenopausal women had irregular and longer menstrual cycles, lower estradiol (E(2)) and estrone (E(1)) levels, and a lower frequency of ovulations vs. the early group. ALP was higher (76.5 +/- 8.3 vs. 58.3 +/- 2.7 IU/L, p = 0.045) compared with the early perimenopausal group. In a subsample (n = 10), OC was associated with ALP (r = 0.69, p < 0.03), FSH was positively related to ucOC concentrations (r = 0.7, p < 0.03), and women with E(1) concentrations <40 pg/ml had double the percentage of ucOC compared with those where E(1) was >40 pg/ml (46.3% +/- 6.6% vs. 22.0% +/- 3. 1%, p < 0.006). Clinical markers of the perimenopause are associated with a nonspecific but inexpensive marker of enhanced bone turnover (i.e., higher ALP) and correlate well with more precise markers of bone activity. These findings suggest that health-promotion strategies for preserving bone should be instituted well before the last menstrual period.

Calcium and the risk for periodontal disease

BACKGROUND

Dietary calcium has long been a candidate to modulate periodontal disease. Animal as well as human studies of calcium intake, bone mineral density, and tooth loss provide a rationale for hypothesizing that low dietary intake of calcium is a risk factor for periodontal disease.

METHODS

We evaluated the role of dietary calcium intake as a contributing risk factor for periodontal disease utilizing the Third National Health and Nutrition Examination Survey (NHANES III), which is representative of the U.S. civilian non-institutionalized population. Dietary calcium intake was determined from a 24-hour dietary recall. The U.S. Department of Agriculture Nutrient Database was used as a source of nutrient composition data. Periodontal disease was measured by attachment loss. In addition, serum calcium was assessed using venous blood samples. Logistic regression analysis was used to examine the association between periodontal disease and dietary calcium intake or serum calcium levels after adjusting for covariants including age, gender, tobacco consumption, and gingival bleeding.

RESULTS

The association of lower dietary calcium intake with periodontal disease was found for young males and females (20 to 39 years of age), and for older males (40 to 59 years of age). The relationship between low dietary calcium intake and increased levels of periodontal disease showed an estimated odds ratio (OR) of 1.84 (95% CI: 1.36 to 2.48) for young males, 1.99 (95% CI: 1.34 to 2.97) for young females, and 1.90 (95% CI: 1.41 to 2.55) for the older group of males. These odds ratios were adjusted for gingival bleeding and tobacco consumption. The dose response was also seen in females, where there was 54% greater risk of periodontal disease for the lowest level of dietary calcium intake (2 to 499 mg) and 27% greater risk in females who took moderate levels of dietary calcium (500 to 799 mg) as compared to those who took 800 mg or more dietary calcium per day. A statistically significant association between low total serum calcium and periodontal disease was found in younger females aged 20 to 39 with OR = 6.11 (95% CI: 2.36 to 15.84) but not for males or older females, after adjusting for tobacco use, gingival bleeding, and dietary calcium intake.

CONCLUSIONS

These results suggest that low dietary intake of calcium results in more severe periodontal disease. Further studies will be needed to better define the role of calcium in periodontal disease and to determine the extent to which calcium supplementation will modulate periodontal disease and tooth loss.

Lower peak bone mass and its decline

There is evidence that two-thirds of the risk of osteoporotic fracture can be predicted from the pre-menopausal bone mineral density. The frequency of osteoporosis in older women may be modifiable by implementing invention strategies in the pre- and peri-menopausal periods. Lower peak bone mineral density and bone loss can be identified in women with altered reproductive hormone or calciotrophic hormone concentrations, or selected lifestyle practices. Alterations in reproductive hormones may occur in adolescence (from an early age of pregnancy or the amenorrhoea of anorexia nervosa or exercise), in the pre-menopause (nulliparity, oophorectomy, early ovarian failure or marginal hormonal status) or in the peri-menopause. Alterations in calciotrophic hormone concentrations include corticosteroid therapy and breast cancer treatment. Lifestyle risk factors include the misuse of alcohol and possibly smoking, physical inactivity or an imbalance in dietary intake. Effective intervention currently consists of treating underlying conditions and monitoring high-risk groups.

Dietary influences on bone mass and bone metabolism: further evidence of a positive link between fruit and vegetable consumption and bone health?

BACKGROUND

The role of nutritional influences on bone health remains largely undefined because most studies have focused attention on calcium intake.

OBJECTIVE

We reported previously that intakes of nutrients found in abundance in fruit and vegetables are positively associated with bone health. We examined this finding further by considering axial and peripheral bone mass and markers of bone metabolism.

DESIGN

This was a cross-sectional study of 62 healthy women aged 45-55 y. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at the lumbar spine and femoral neck and by peripheral quantitative computed tomography at the ultradistal radial total, trabecular, and cortical sites. Bone resorption was calculated by measuring urinary excretion of pyridinoline and deoxypyridinoline and bone formation by measuring serum osteocalcin. Nutrient intakes were assessed by using a validated food-frequency questionnaire; other lifestyle factors were assessed by additional questions.

RESULTS

After present energy intake was controlled for, higher intakes of magnesium, potassium, and alcohol were associated with higher total bone mass by Pearson correlation (P < 0.05 to P < 0.005). Femoral neck BMD was higher in women who had consumed high amounts of fruit in their childhood than in women who had consumed medium or low amounts (P < 0.01). In a regression analysis with age, weight, height, menstrual status, and dietary intake entered into the model, magnesium intake accounted for 12.3% of the variation in pyridinoline excretion and 12% of the variation in deoxypyridinoline excretion. Alcohol and potassium intakes accounted for 18.1% of the variation in total forearm bone mass.

CONCLUSION

The BMD results confirm our previous work (but at peripheral bone mass sites), and our findings associating bone resorption with dietary factors provide further evidence of a positive link between fruit and vegetable consumption and bone health.

Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women

OBJECTIVES

To determine the relationships between serum vitamin D metabolites, bone mass, and dietary calcium and phosphorus in a cohort of 510 healthy Danish perimenopausal women.

DESIGN

A population-based cross-sectional study.

SUBJECTS

A total of 510 healthy women aged 45-58 years, with amenorrhoea for 3-24 months. None of the women was using hormone replacement therapy.

MEASUREMENTS

Measurements of total bone mineral content and regional bone mineral density were performed by dual-energy X-ray absorptiometry. Analyses of serum levels of 25-OHD and 1,25-(OH)2D, intact PTH, ionized calcium and phosphate, as well as biochemical markers of bone turnover in blood and urine. Assessment of calcium and phosphorus intake using dietary records.

RESULTS

A consistent inverse relationship between serum 1,25-(OH)2D and bone mineral content/ density was found in whole-body mineral content (P = 0.001), spine (P = 0.005) and femoral neck (P<0.05). There was a positive relationship between levels of 1,25-(OH)2D and biochemical bone markers, indicating that high levels of 1,25-(OH)2D are accompanied by increased bone turnover. The dietary calcium:phosphorus ratio was inversely related to serum 1,25-(OH)2D (P = 0.04) and positively related to bone mineral density (P<0.0005). No relationships could be detected between levels of PTH, serum ionized calcium and phosphate, and serum vitamin D metabolites.

CONCLUSION

Within normal physiological range, elevated levels of 1,25-(OH)2D were associated with decreased bone mineral density and content, reduced calcium:phosphorus ratio in the diet and increased bone turnover.

Bone mineral density and its change in pre-and perimenopausal white women: the Michigan Bone Health Study

There is a need to better understand potential bone mineral density (BMD) loss during the menopausal transition since this period may include the initiation of interventions. The study purpose was to determine if there was BMD loss at the femoral neck, lumbar spine, or total body bone sites in a population-based study of women approaching or transitioning the midlife. The 583 enrollees were 25-45 years of age at the first of four annual measurements from 1992 through 1996. Bone mineral content and bone width were measured using dual-energy X-ray absorptiometry. Considering all enrollees collectively, there was a significant 3-year decline (1%) in BMD at the femoral neck over the 3-year period (p = 0.076). There was no significant annual change in the lumbar spine (p = 0.11), and a significant annual increase in the total body BMD (p = 0.0003). Within subgroups and cross-sectionally, BMD values of the femoral neck were 5% lower in women classified as perimenopausal compared with premenopausal enrollees; BMD was 3% and 1% lower at the lumbar spine and total body site, respectively. Longitudinally, among perimenopausal women, a double oophorectomy was associated with BMD loss in the spine (p = 0.0003), even though 75-85% of these women had a hormone replacement prescription at some time during the study period. In summary, the site with evidence of loss was the femoral neck, specifically among perimenopausal women. There was little evidence of substantial total body or lumbar spine BMD loss in premenopausal women with ovaries who maintained follicle-stimulating hormone levels < 20 mIU/l in the early follicular period. Double oophorectomy, even with hormone replacement, was associated with bone loss.

Can Follicle-Stimulating Hormone be used to Define Menopausal Status?

OBJECTIVE

To assess the ability of the level of follicle-stimulating hormone (FSH) to distinguish among premenopausal, perimenopausal, and postmenopausal women.

METHODS

We examined cross-sectional and longitudinal data from the second phase of the Massachusetts Women's Health Study (1986 to 1995), a population-based cohort of 427 premenopausal and perimenopausal women identified from the first phase of the Massachusetts Women's Health Study (1981 to 1986).

RESULTS

Boxplots of FSH levels throughout the menopausal transition displayed considerable overlap. Logistic regressions and their resulting receiver operating characteristic curves further demonstrated that, although FSH is a statistically significant predictor of menopausal status, no single value of FSH is expedient for distinguishing premenopausal from perimenopausal or perimenopausal from postmenopausal women.

CONCLUSION

FSH alone is not an effective predictor of transition into the perimenopausal or postmenopausal period. Specifically, the frequently recommended FSH cutoff of 40 IU/L is inappropriate by itself for clinical determination of postmenopausal status.

Vitamin D and bone mineral density

Bone mineral density (BMD) at the lumbar spine and the neck of femur and serum concentrations of 25-hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), alkaline phosphatase, calcium, albumin, creatinine and phosphate were measured in a group of 166 postmenopausal women (30-79 years) attending a bone clinic for bone density measurements. Four subjects with suspected primary hyperparathyroidism were excluded from analysis. BMD at the lumbar spine was correlated with body mass index (BMI) (r = 0.278, p = 0.0003), age (r = -0.194, p = 0.0134) and serum 25OHD (r = 0.188, p = 0.0167). BMD at the neck of femur correlated with BMI (r = 0.391, p < 0.0001), age (r = -0.356, p < 0.0001), PTH (r = -0.156, p = 0.047) and serum 25OHD (r = 0.231, p = 0.0031). Stepwise multiple regression analysis showed that age, BMI and serum 25OHD contributed to the variation in BMD at lumbar spine. At the neck of femur, PTH was an additional contributor. We conclude that serum 25OHD makes a contribution to BMD a lumbar spine and neck of femur.

Perimenopausal bone density screening--will it help prevent osteoporosis?

OBJECTIVE

To estimate the potential efficacy and cost-effectiveness of hormone replacement therapy (HRT) in the prevention of osteoporotic fractures, with and without the assistance of perimenopausal bone mineral density (BMD) screening.

METHOD

Residual lifetime fracture experience of a hypothetical cohort of 100,000. British women aged 45 years at baseline, modelled using prevailing UK mortality and fracture rates. Appropriate fracture risk gradients were used to estimate the distribution of future fragility fractures (distal forearm, proximal femur and clinically diagnosed vertebral fractures) according to quarters of baseline bone density measured at fracture specific sites. We assumed that 72% of the population could be contacted and would attend for HRT counselling, with or without bone densitometry, that 10 years of continuous HRT use would reduce fracture rates by 50%, and that compliance with HRT might vary between 10% and 50%. Universal recommendation of HRT was compared to selective treatment protocols offering HRT to those women whose BMD fell below the 25th, 50th or 75th percentile of BMD at the lumbar spine, femoral neck or distal forearm, measured either singly or in combination.

RESULTS

The proportion of future fractures averted was closely related to compliance with therapy, but for any given level of compliance, universal treatment always achieved the greatest reduction in fractures. If compliance was 10% universal HRT was also the most cost-effective strategy, but if compliance was higher or if the unit cost of HRT increased, selective strategies were often more cost-effective. The sensitivity of BMD screening in identifying women at risk of future fracture could be increased by relaxing the BMD decision threshold, or expanding the number of skeletal sites measured, or both. However increments in test sensitivity were always accompanied by reductions in specificity.

CONCLUSIONS

If BMD measurement does not influence compliance, then universal treatment with HRT is likely to prevent more fractures, at a similar or lower average cost per fracture averted, than selective therapy. However, if BMD screening leads to increased compliance, or if more expensive forms of treatment were used, then our model suggests a favourable impact of screening on the numbers and/or net cost of fractures prevented.