Estrogen status and heredity are major determinants of premenopausal bone mass

A Prospective Evaluation of Serum Vitamin D (1, 25(OH)2 D3) and Endogenous Sex Hormone Levels in Colorectal Cancer Patients

Background: Data on 25-OH VD concentrations and the associated factors in colorectal cancer (CRC) patients are scarce and need to be investigated.

Methods: A total of 200 CRC patients participated in this cross-sectional study conducted in Pakistan. Socio-demographic and other health data were collected in a pretested questionnaire. Serum measurements of Vitamin D (1, 25(OH)₂ D₃) levels and hormones were performed. Association of age, sex, primary site, effects of hormone therapy and stage of disease and selected reproductive health indicators on vitamin D status were primarily scrutinized by univariate analysis.

Results: Mean age of the population was 55.3 years (±15.6; Range: 20–90 years). Estradiol concentration was considerably elevated in young females compared to young male patients (p < 0.001). The concentrations of FSH, LH testosterone and estradiol were significantly lower in post-menopausal female CRC patients as compared to their male counterparts of old age (p, for all trends < 0.05). Both LH and FSH showed significant gender difference but only in older patients. Level of estrogen was markedly decreased in older post-menopausal CRC patients compared to premenopausal CRC patients, which might be associated with CRC progression. In the group of women, who “ever used hormone therapy” had differences of statistical significance (p, for all trends < 0.05) in their mean serum 25-OH VD concentrations, while in the group of women who “never used hormone therapy” had non-significant differences in their mean serum 25-OH VD concentrations (p, for all trends > 0.05). High 25-OH VD concentrations were observed in women who had their menarche at the age of 15 years or more. Nulliparous women had the highest mean 25-OH VD concentrations as compared to unparious or multiparious women. In addition, women having their menopause at 40–44 years of age had the highest 25-OH VD concentrations, although the difference was not significant (p = 0.08). Women who “never used any oral contraceptive” had higher 25-OH VD concentrations as compared to those “whoever used oral contraceptives.”

Conclusion: Our findings suggest that vitamin D has a positive effect on the development of CRC through the mediation of hormones. Other health and reproductive traits that affect hormone levels may have an indirect effect on the development of CRC. Further potential studies that directly evaluate levels of circulating hormones and hormone therapy in women in association to 25-OH VD concentrations, as well as their possible role in colorectal cancer risk, would be vastly edifying.

Retinoic acid signaling in ovarian folliculogenesis and steroidogenesis

Retinoids are essential for reproduction. Most research has focused on the role of retinoic acid signaling in the regulation of meiosis during early fetal germ cell development. However, less attention has been paid to the possible effects of retinoic acid signaling in adult female gonads. Retinoic acid, its receptors, and the key enzymes required for retinoic acid synthesis are expressed in the ovaries and they are involved in the regulation of folliculogenesis and steroidogenesis. Exposure to compounds that can interfere with normal retinoic acid signaling is associated with adverse ovarian outcomes, including altered steroidogenesis and reduction in indicators of ovarian reserve in women and laboratory animal models. These observations call for more attention to retinoids as regulators of adult ovarian physiology and as possible targets of endocrine disruption by environmental chemicals. In this review, we summarize the current knowledge of retinoids in folliculogenesis and steroidogenesis in post-pubertal mammalian ovaries.

Poor sleep quality and later sleep timing are risk factors for osteopenia and sarcopenia in middle-aged men and women: The NEO study

CONTEXT

Sleep deprivation has detrimental metabolic consequences. Osteopenia and sarcopenia usually occur together and increase risk of fractures and disease. Results from studies linking sleep parameters to osteopenia or sarcopenia are scarce and inconsistent.

OBJECTIVE

To examine the associations of sleep parameters with osteopenia and sarcopenia, considering the influence of sex and menopause.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional analysis of 915 participants (45-65 years, 56% women, BMI 26 (range: 18-56) kg/m2) in the Netherlands Epidemiology of Obesity (NEO) study, a population-based cohort study. Sleep duration, quality, and timing were assessed with the Pittsburgh Sleep Quality Index (PSQI); bone mineral density and relative appendicular muscle mass were measured by DXA scans. Linear and logistic regressions were performed to associate sleep parameters to bone mineral density, relative appendicular muscle mass, osteopenia (t-score between -1 and -2.5) and sarcopenia (1 SD below average muscle mass).

RESULTS

After adjustment for confounding factors, one unit increase in PSQI score (OR and 95% CI, 1.09, 1.03-1.14), declined self-rated sleep quality (1.76, 1.03-3.01), sleep latency (1.18, 1.06-1.31), and a one hour later sleep timing (1.51, 1.08-2.11), but not sleep duration (1.05, 0.90-1.23), were associated with osteopenia. PSQI score (1.10, 1.02-1.19) was also associated with sarcopenia; OR's of sleep latency and later mid-sleep time with sarcopenia were 1.14 (0.99-1.31) and 1.54 (0.91-2.61), respectively. Associations were somewhat stronger in women and varied per menopausal status.

CONCLUSIONS

These results suggest that decreased sleep quality and a later sleep timing are risk factors for osteopenia and sarcopenia in middle aged individuals.

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.

Equol inhibits growth, induces atresia, and inhibits steroidogenesis of mouse antral follicles in vitro

Equol is a non-steroidal estrogen metabolite produced by microbial conversion of daidzein, a major soy isoflavone, in the gut of some humans and many animal species. Isoflavones and their metabolites can affect endogenous estradiol production, action, and metabolism, potentially influencing ovarian follicle function. However, no studies have examined the effects of equol on intact ovarian antral follicles, which are responsible for sex steroid synthesis and further development into ovulatory follicles. Thus, the present study tested the hypothesis that equol inhibits antral follicle growth, increases follicle atresia, and inhibits steroidogenesis in the adult mouse ovary. To test this hypothesis, antral follicles isolated from adult CD-1 mice were cultured with vehicle control (dimethyl sulfoxide; DMSO) or equol (600 nM, 6 μM, 36 μM, and 100 μM) for 48 and 96 h. Every 24h, follicle diameters were measured to monitor growth. At 48 and 96 h, the culture medium was subjected to measurement of hormone levels, and the cultured follicles were subjected to gene expression analysis. Additionally, follicles were histologically evaluated for signs of atresia after 96 h of culture. The results indicate that equol (100 μM) inhibited follicle growth, altered the mRNA levels of bcl2-associated X protein and B cell leukemia/lymphoma 2, and induced follicle atresia. Further, equol decreased the levels of estradiol, testosterone, androstenedione, and progesterone, and it decreased mRNA levels of cholesterol side-chain cleavage, steroid 17-α-hydroxalase, and aromatase. Collectively, these data indicate that equol inhibits growth, increases atresia, and inhibits steroidogenesis of cultured mouse antral follicles.

Genistein exposure inhibits growth and alters steroidogenesis in adult mouse antral follicles

Genistein is a naturally occurring isoflavone phytoestrogen commonly found in plant products such as soybeans, lentils, and chickpeas. Genistein, like other phytoestrogens, has the potential to mimic, enhance, or impair the estradiol biosynthesis pathway, thereby potentially altering ovarian follicle growth. Previous studies have inconsistently indicated that genistein exposure may alter granulosa cell proliferation and hormone production, but no studies have examined the effects of genistein on intact antral follicles. Thus, this study was designed to test the hypothesis that genistein exposure inhibits follicle growth and steroidogenesis in intact antral follicles. To test this hypothesis, antral follicles isolated from CD-1 mice were cultured with vehicle (dimethyl sulfoxide; DMSO) or genistein (6.0 and 36μM) for 18-96h. Every 24h, follicle diameters were measured to assess growth. At the end of each culture period, the media were pooled to measure hormone levels, and the cultured follicles were collected to measure expression of cell cycle regulators and steroidogenic enzymes. The results indicate that genistein (36μM) inhibits growth of mouse antral follicles. Additionally, genistein (6.0 and 36μM) increases progesterone, testosterone, and dehydroepiandrosterone (DHEA) levels, but decreases estrone and estradiol levels. The results also indicate that genistein alters the expression of steroidogenic enzymes at 24, 72 and 96h, and the expression of cell cycle regulators at 18h. These data indicate that genistein exposure inhibits antral follicle growth by inhibiting the cell cycle, alters sex steroid hormone levels, and dysregulates steroidogenic enzymes in cultured mouse antral follicles.

Di(2-ethylhexyl) phthalate inhibits antral follicle growth, induces atresia, and inhibits steroid hormone production in cultured mouse antral follicles

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental toxicant found in consumer products that causes ovarian toxicity. Antral follicles are the functional ovarian units and must undergo growth, survival from atresia, and proper regulation of steroidogenesis to ovulate and produce hormones. Previous studies have determined that DEHP inhibits antral follicle growth and decreases estradiol levels in vitro; however, the mechanism by which DEHP elicits these effects is unknown. The present study tested the hypothesis that DEHP directly alters regulators of the cell cycle, apoptosis, and steroidogenesis to inhibit antral follicle functionality. Antral follicles from adult CD-1 mice were cultured with vehicle control or DEHP (1-100 μg/ml) for 24-96 h to establish the temporal effects of DEHP on the follicle. Following 24-96 h of culture, antral follicles were subjected to gene expression analysis, and media were subjected to measurements of hormone levels. DEHP increased the mRNA levels of cyclin D2, cyclin dependent kinase 4, cyclin E1, cyclin A2, and cyclin B1 and decreased the levels of cyclin-dependent kinase inhibitor 1A prior to growth inhibition. Additionally, DEHP increased the mRNA levels of BCL2-associated agonist of cell death, BCL2-associated X protein, BCL2-related ovarian killer protein, B-cell leukemia/lymphoma 2, and Bcl2-like 10, leading to an increase in atresia. Further, DEHP decreased the levels of progesterone, androstenedione, and testosterone prior to the decrease in estradiol levels, with decreased mRNA levels of side-chain cleavage, 17α-hydroxylase-17,20-desmolase, 17β-hydroxysteroid dehydrogenase, and aromatase. Collectively, DEHP directly alters antral follicle functionality by inhibiting growth, inducing atresia, and inhibiting steroidogenesis.

The effects of phthalates on the ovary

Phthalates are commonly used as plasticizers in the manufacturing of flexible polyvinyl chloride products. Large production volumes of phthalates and their widespread use in common consumer, medical, building, and personal care products lead to ubiquitous human exposure via oral ingestion, inhalation, and dermal contact. Recently, several phthalates have been classified as reproductive toxicants and endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormone signaling. Therefore, exposure to phthalates represents a public health concern. Currently, the effects of phthalates on male reproduction are better understood than the effects on female reproduction. This is of concern because women are often exposed to higher levels of phthalates than men through their extensive use of personal care and cosmetic products. In the female, a primary regulator of reproductive and endocrine function is the ovary. Specifically, the ovary is responsible for folliculogenesis, the proper maturation of gametes for fertilization, and steroidogenesis, and the synthesis of necessary sex steroid hormones. Any defect in the regulation of these processes can cause complications for reproductive and non-reproductive health. For instance, phthalate-induced defects in folliculogenesis and steroidogenesis can cause infertility, premature ovarian failure, and non-reproductive disorders. Presently, there is a paucity of knowledge on the effects of phthalates on normal ovarian function; however, recent work has established the ovary as a target of phthalate toxicity. This review summarizes what is currently known about the effects of phthalates on the ovary and the mechanisms by which phthalates exert ovarian toxicity, with a particular focus on the effects on folliculogenesis and steroidogenesis. Further, this review outlines future directions, including the necessity of examining the effects of phthalates at doses that mimic human exposure.

Pubertal timing, bone acquisition, and risk of fracture throughout life

Pubertal maturation plays a fundamental role in bone acquisition. In retrospective epidemiological surveys in pre- and postmenopausal women, relatively later menarcheal age was associated with low bone mineral mass and increased risk of osteoporotic fracture. This association was usually ascribed to shorter time exposure to estrogen from the onset of pubertal maturation to peak bone mass attainment. Recent prospective studies in healthy children and adolescents do not corroborate the limited estrogen exposure hypothesis. In prepubertal girls who will experience later menarche, a reduced bone mineral density was observed before the onset of pubertal maturation, with no further accumulated deficit until peak bone mass attainment. In young adulthood, later menarche is associated with impaired microstructural bone components and reduced mechanical resistance. This intrinsic bone deficit can explain the fact that later menarche increases fracture risk during childhood and adolescence. In healthy individuals, both pubertal timing and bone development share several similar characteristics including wide physiological variability and strong effect of heritable factors but moderate influence of environmental determinants such as nutrition and physical activity. Several conditions modify pubertal timing and bone acquisition, a certain number of them acting in concert on both traits. Taken together, these facts should prompt the search for common genetic regulators of pubertal timing and bone acquisition. It should also open epigenetic investigation avenues to pinpoint which environmental exposure in fetal and infancy life, such as vitamin D, calcium, and/or protein supplies, influences both pubertal timing and bone acquisition.

Associations between sleep duration, daytime nap duration, and osteoporosis vary by sex, menopause, and sleep quality

CONTEXT

Associations between sleep, daytime nap duration, and osteoporosis remain uncertain, and far less is even known about the influence of sex, menopause, and sleep quality on them.

OBJECTIVE

The objective of the study was to test the associations between sleep, daytime nap duration, and osteoporosis and whether they vary by sex, menopause, and sleep quality.

DESIGN, SETTING, AND PATIENTS

This cross-sectional study was based on two communities in China. A total of 8688 participants (3950 males and 4738 females) aged 40 years or older were enrolled in the study.

MAIN OUTCOMES MEASURES

Self-reported sleep duration, daytime nap duration, sleep quality, and calcaneus bone mineral density were recorded.

RESULTS

Sleep duration of 8-9 h/d and nap duration of 0 min/d were regarded as reference values. In postmenopausal women, risks (odds ratio and 95% confidence interval) of osteoporosis for sleep durations of 7-8 h/d, 9-10 h/d, and 10 h/d or longer were 1.531 (1.106, 2.121), 1.360 (1.035, 1.787), and 1.569 (1.146, 2.149), respectively (P < .05), and risks of osteoporosis for daytime nap durations of 30-60 min/d and longer than 60 min/d were 1.553 (1.212-1.989) and 1.645 (1.250-2.165), respectively (P < .05). However, a significant difference was not consistently observed in men or premenopausal women, regardless of sleep or daytime nap duration. As for sleep quality, positive results were seen most remarkably in postmenopausal females with good sleep.

CONCLUSIONS

Sleep durations of 7-8 h/d, 9-10 h/d, and 10 h/d or longer, as well as longer daytime napping times, tend to present higher risks of having osteoporosis, and this tendency is most obvious in postmenopausal women reporting good-quality sleep.

Premenopausal women with a distal radial fracture have deteriorated trabecular bone density and morphology compared with controls without a fracture

BACKGROUND

Measurement of bone mineral density by dual x-ray absorptiometry combined with clinical risk factors is currently the gold standard in diagnosing osteoporosis. Advanced imaging has shown that older patients with fragility fractures have poor bone microarchitecture, often independent of low bone mineral density. We hypothesized that premenopausal women with a fracture of the distal end of the radius have similar bone mineral density but altered bone microarchitecture compared with control subjects without a fracture.

METHODS

Forty premenopausal women with a recent distal radial fracture were prospectively recruited and matched with eighty control subjects without a fracture. Primary outcome variables included trabecular and cortical microarchitecture at the distal end of the radius and tibia by high-resolution peripheral quantitative computed tomography. Bone mineral density at the wrist, hip, and lumbar spine was also measured by dual x-ray absorptiometry.

RESULTS

The fracture and control groups did not differ with regard to age, race, or body mass index. Bone mineral density was similar at the femoral neck, lumbar spine, and distal one-third of the radius, but tended to be lower in the fracture group at the hip and ultradistal part of the radius (p = 0.06). Trabecular microarchitecture was deteriorated in the fracture group compared with the control group at both the distal end of the radius and distal end of the tibia. At the distal end of the radius, the fracture group had lower total density and lower trabecular density, number, and thickness compared with the control group (-6% to -14%; p < 0.05 for all). At the distal end of the tibia, total density, trabecular density, trabecular thickness, and cortical thickness were lower in the fracture group than in the control group (-7% to -14%; p < 0.01). Conditional logistic regression showed that trabecular density, thickness, separation, and distribution of trabecular separation remained significantly associated with fracture after adjustment for age and ultradistal radial bone mineral density (adjusted odds ratios [OR]: 2.01 to 2.98; p < 0.05). At the tibia, total density, trabecular density, thickness, cortical area, and cortical thickness remained significantly associated with fracture after adjustment for age and femoral neck bone mineral density (adjusted OR:1.62 to 2.40; p < 0.05).

CONCLUSIONS

Despite similar bone mineral density values by dual x-ray absorptiometry, premenopausal women with a distal radial fracture have significantly poorer bone microarchitecture at the distal end of the radius and tibia compared with control subjects without a fracture. Early identification of women with poor bone health offers opportunities for interventions aimed at preventing further deterioration and reducing fracture risk.

Genetic and environmental factors in human osteoporosis

Osteoporosis is a common disorder, with prolongation of the average life span it has become a major public health problem. On the formation of osteoporosis genetic factors and environmental influences could play a role then it is considered as multi-factorial. Because a variety of functions to affect susceptibility to the formation of osteoporosis VDR-F, VDR-B, COL1A1, ESR1X, ESR1P and CTR are thought to be candidate genes. In this study, the aim is to investigate the relationship between these genes polymorphism and bone mineral density (BMD) values of lumbar vertebra and femoral neck in 188 Turkish people. Lumbar spine and femoral neck BMD of the individuals included in the study were measured by the dual X-ray absorptiometry method. The genotyped polymorphisms by simultaneous amplification of five regions of the genome, containing six SNPs of interest and detecting the amplified product, using the kit MetaBone Clinical Arrays(®). Statistical analyses indicated that; VDR-B gene polymorphisms major (P = 0.013), VDR-F polymorphisms have minor (P = 0.082) effect on femur BMD. None of the other genes has any significant effect on spinal BMD. Patient age, body mass index and diet has significant effect on femoral and spinal BMD. Osteoporosis is a multi-factorial disease and many genetic and non-genetic risk factors contribute to the development of osteoporosis. Early detection of a genetic predisposition to osteoporosis should allow delay and/or limit unfavorable changes in the bone tissue.

A framework for the development of guidelines for the management of glucocorticoid-induced osteoporosis

This paper provides a framework for the development of national guidelines for the management of glucocorticoid-induced osteoporosis in men and women aged 18 years and over in whom oral glucocorticoid therapy is considered for 3 months or longer.

INTRODUCTION

The need for updated guidelines for Europe and other parts of the world was recognised by the International Osteoporosis Foundation and the European Calcified Tissue Society, which set up a joint Guideline Working Group at the end of 2010.

METHODS AND RESULTS

The epidemiology of GIO is reviewed. Assessment of risk used a fracture probability-based approach, and intervention thresholds were based on 10-year probabilities using FRAX. The efficacy of intervention was assessed by a systematic review.

CONCLUSIONS

Guidance for glucocorticoid-induced osteoporosis is updated in the light of new treatments and methods of assessment. National guidelines derived from this resource need to be tailored within the national healthcare framework of each country.

High prevalence of low vitamin D and musculoskeletal complaints in women with breast cancer

Reduced vitamin D levels may play a significant role in the development of fractures and musculoskeletal pains reported in patients on aromatase inhibitors (AIs) for breast cancer. In this study, we evaluated the vitamin D status in postmenopausal women with non-metastatic breast cancer who were about to start AI therapy. This study was conducted on community dwelling postmenopausal subjects, aged 35-80 years, with early non-metastatic breast cancer (up to stage IIIA), who were about to start therapy using third generation AIs. Symptoms of joint and muscle pains were obtained using a modified Leuven menopausal questionnaire. 25-hydroxyvitamin D [25(OH)D] was evaluated by radioimmunoassay while bone mineral density (BMD) of the lumbar spine and the proximal femur by dual energy x-ray absorptiometry (DXA). Of the 145 participants (mean age = 60.96 ± 0.88 years), 63 of 145 (43.5%) had baseline levels of 25(OH)D of < 20 ng/mL (deficient), 50 of 145 (34.5%) had levels between 20 and 29 ng/mL (insufficient), and only 32 of 145 (22%) had ≥ 30 ng/mL (sufficient); thus, 113 of 145 (78%) had low 25(OH)D levels (i.e., < 30 ng/mL). Arthralgias and myalgias were found in 61.3% and 43% of patients, respectively; and of those, 83.3% and 88.1% had 25(OH)D of < 30 ng/mL, respectively. Prevalence of vitamin D deficiency is high in breast cancer women and this may increase the risk of bone loss and fractures in those who are going to start AIs. Moreover, musculoskeletal pains are common in breast cancer women, even before the initiation of AIs and in association with low vitamin D in the majority. Future studies may be needed to establish the contribution of low vitamin D, if any, on the prevalence of musculoskeletal pains in women on AIs.

Bone mass and sex steroids in postmenarcheal adolescents and adult women with Type 1 diabetes mellitus

OBJECTIVE

The aim of this study was to compare the bone mass in young adolescents and adult women with Type 1 diabetes mellitus (T1DM) and determine its relationship with sex steroid and sex hormone-binding globulin (SHBG) levels.

DESIGN

Cross-sectional study.

PATIENTS

We studied a group of adolescents and adult women with T1DM (n=45) and 50 healthy controls (C) matched by gynecological age and body mass index in a case-control study. Girls with menarche within the last 18-40 months (n=17 T1DM and 32 C) and adult women (age=30.4+1.4 years; n=28 T1DM and 18 C) were recruited.

MEASUREMENTS

Bone mass was evaluated with a GE Lunar Prodigy densitometer. Sex steroid levels were measured by radioimmunoassay.

RESULTS

Bone mass was lower in adolescents with T1DM than in control adolescents, but was similar in both groups of postmenarcheal girls after adjusting for age, lean, and fat mass. However, adult T1DM women exhibited lower adjusted and unadjusted (P<.05) Z-femoral neck (-0.2±0.2 vs. 0.4±0.2) and bone mineral content (BMC) (2306±61 vs. 2645±79 g) than adult controls. Adult controls and T1DM adults showed higher whole body BMC than adolescent controls and T1DM adolescents, respectively. Bone mass in T1DM did not correlate with estradiol, free estradiol, testosterone, SHBG, or HbA1c levels.

CONCLUSIONS

The diminished bone mass observed in adult T1DM women does not appear to be related to sex steroid levels. In young adolescents with T1DM, the observed decrease in bone mass appears to be related to differences in body composition and age.

Velocities of bone mineral accrual in black and white American children

Black adults have higher bone mass than whites in the United States, but it is not clear when black children gain bone mineral faster than white children. We performed a cohort study to compare the growth velocity of total-body bone mineral content (TBMC) between black and white children of the same sex at different ages and stages of sexual maturity. TBMC and total-body area were measured in a cohort of 188 black and white boys and girls aged 5 to 15 years annually for up to 4 years. Rates of change in TBMC and area were found to vary with age and with Tanner stage. For both TBMC and area, growth velocities between black and white children differed significantly across Tanner stages. Age-specific velocities were higher in black children during prepuberty and initial entry into puberty but reversed in subsequent Tanner stages. Despite earlier entry into each Tanner stage, black children spent only an average of only 0.2 year longer in Tanner stages II through IV, and total gain in TBMC from age 5 to 15 was not higher in whites. In conclusion, the higher bone mass in black adults compared with whites cannot be attributed to faster accrual during puberty. It is due to black children's higher rate of bone mineral accrual in prepuberty and plausibly in postpuberty. Most of the racial difference in TBMC velocity can be explained by growth in size.

Effects of polymorphisms of the sex hormone-binding globulin (SHBG) gene on free estradiol and bone mineral density

BACKGROUND

Polymorphisms of the sex hormone-binding globulin (SHBG) gene are associated with differences in SHBG levels, influencing the risk for breast cancer and polycystic ovarian syndrome, but no association has been reported for osteoporosis in postmenopausal women.

OBJECTIVE

To determine the effect of G to A substitution in the 5'UTR (rs1799941) and the Asp356Asn (rs6259) polymorphisms of the SHBG gene on bone mineral density (BMD).

METHODS

This is a cross-sectional study in a university-based research center from May, 2002 to December, 2007. A total of two hundred and thirteen healthy postmenopausal Caucasian women > or = 1 year from last menstrual period participated to this study. Serum estradiol by ultrasensitive radioimmnunoassay, serum sex hormone-binding globulin by immunoradiometric assay, and urinary NTx by enzyme-linked immunoassay were measured. BMD measurements were performed by dual energy X-ray absorptiometry and genotyping by Pyrosequencing.

RESULTS

There were no significant differences in SHBG levels associated with either rs1799941 or rs6259. Using a p value of <0.00625 for significance, we found that subjects with the A allele (GA+AA) for the rs1799941, had a trend for lower free estradiol index (FEI) compared to the GG genotype (p=0.04). They also had significantly lower BMD at the intertrochanter (p=0.003) and trend for lower BMD at the total hip (p=0.02). There was no significant difference in FEI levels between the genotypes for the rs6259 polymorphism, but women with the Asn allele (Asp/Asn+Asn/Asn), had significantly lower BMD in the total femur (p=0.004) and intertrochanter (0.002) compared to those with the Asp/Asp genotype.

CONCLUSIONS

Our data suggest that polymorphisms of the SHBG gene are associated with significant differences in BMD at the proximal femur sites. Thus, genetic variations in the SHBG gene may influence BMD at the hip in postmenopausal women.

History of amenorrhoea compromises some of the exercise-induced benefits in cortical and trabecular bone in the peripheral and axial skeleton: a study in retired elite gymnasts

BACKGROUND

Female gymnasts frequently present with overt signs of hypoestrogenism, such as late menarche or menstrual dysfunction. The objective was to investigate the impact of history of amenorrhoea on the exercise-induced skeletal benefits in bone geometry and volumetric density in retired elite gymnasts.

SUBJECTS AND METHODS

24 retired artistic gymnasts, aged 17-36 years, who had been training for at least 15 h/week at the peak of their career and had been retired for 3-18 years were recruited. They had not been engaged in more than 2 h/week of regular physical activity since retirement. Former gymnasts who reported history of amenorrhoea ('AME', n=12: either primary or secondary amenorrhoea) were compared with former gymnasts ('NO-AME', n=12) and controls ('C', n=26) who did not report history of amenorrhoea. Bone mineral content (BMC), total bone area (ToA) and total volumetric density (ToD) were measured by pQCT at the radius and tibia (4% and 66%). Trabecular volumetric density (TrD) and bone strength index (BSI) were measured at the 4% sites. Cortical area (CoA), cortical thickness (CoTh), medullary area (MedA), cortical volumetric density (CoD), stress-strain index (SSI) and muscle and fat area were measured at the 66% sites. Spinal BMC, areal BMD and bone mineral apparent density (BMAD) were measured by DXA.

RESULTS

Menarcheal age was delayed in AME when compared to NO-AME (16.4+/-0.5 years vs. 13.3+/-0.4 years, p<0.001). No differences were detected between AME and C for height-adjusted spinal BMC, aBMD and BMAD, TrD and BSI at the distal radius and tibia, CoA at the proximal radius, whereas these parameters were greater in NO-AME than C (p<0.05-0.005). AME had lower TrD and BSI at the distal radius, and lower spinal BMAD than NO-AME (p<0.05) but they had greater ToA at the distal radius (p<0.05).

CONCLUSION

Greater spinal BMC, aBMD and BMAD as well as trabecular volumetric density and bone strength in the peripheral skeleton were found in former gymnasts without a history of menstrual dysfunction but not in those who reported either primary or secondary amenorrhoea. History of amenorrhoea may have compromised some of the skeletal benefits associated with high-impact gymnastics training.

The influence of pubertal timing on bone mass acquisition: a predetermined trajectory detectable five years before menarche

BACKGROUND

Later menarcheal age (MENA) is a risk factor for osteoporosis. It is associated with low peak bone mass (PBM). Like PBM, MENA is under strong genetic influence. We hypothesized that MENA-related bone mass differences could be predetermined before puberty.

METHODS

We tested this hypothesis in 124 healthy subjects followed from age 7.9 to 20.4 yr with dual-energy x-ray absorptiometry assessment at mean ages of 8.9, 10.0, 12.4, and 16.4 yr. Six sites were measured: radial metaphysis, radial diaphysis, femoral neck, trochanter, femoral diaphysis, and L2-L4. Mean MENA (+/-SD) was 13.0 +/- 1.2 yr. The cohort was segregated by the median of MENA into LATER (14.0 +/- 0.7 yr) and EARLIER (12.1 +/- 0.7 yr) subgroups.

RESULTS

At 20.4 +/- 0.6 yr, areal bone mineral density (aBMD) was lower in the LATER than the EARLIER subgroup at all six sites, with a mean difference of -0.31 Z-score (P = 0.022). Lower Z-scores in the LATER than in the EARLIER subgroup were observed at all sites at mean ages of 10.0, 12.4, and 16.4 yr, and before pubertal maturation, i.e. at 8.9 yr with a mean Z-score difference of -0.34 (P = 0.016). From mean age 8.9 to 20.4 yr, aBMD gains of all sites were similar in LATER and EARLIER subgroups, with mean of +301 and +308 mg/cm(2) (P = 0.402), respectively.

CONCLUSIONS

In prepubertal girls who will experience later menarche, a deficit in aBMD can already be observed before the onset of pubertal maturation, with no further accumulated deficit until PBM compared to girls with earlier menarche. This suggests that shorter estrogen exposure from prepuberty to PBM is not the main factor for increased osteoporosis risk associated with later menarche. Rather common genetic determinants of low bone mass and later puberty could be involved.

Prediction of changes in bone mineral density in postmenopausal women treated with once-weekly bisphosphonates

BACKGROUND

In clinical practice, bone mineral density (BMD) determined by dual-energy x-ray absorptiometry is used to monitor response to osteoporosis therapy. However, 1 to 2 yr are usually required to assess patients' BMD responses. The possibility of earlier indicators of a response or nonresponse to treatment, such as changes in bone turnover markers (BTMs), is of interest to physicians and patients.

METHODS

In this post hoc analysis of women treated with once-weekly bisphosphonates, we examined the association of tertile percentage change from baseline in BTMs at 3 or 6 months and association of several baseline clinical characteristics with 24-month percentage change from baseline in BMD and with percentage of patients showing BMD nonresponse (defined as BMD loss at two or more of four sites) at 24 months. Multivariable analysis was performed to determine which factors were independently associated with BMD nonresponse.

RESULTS

Patients in the tertile with the greatest decrease in each of the BTMs had the greatest mean increase in BMD and the lowest percentage of BMD nonresponders at 24 months. Several characteristics were independently associated with BMD nonresponse, including smaller 3-month reductions from baseline in serum C-terminal telopeptide of type 1 collagen, bone-specific alkaline phosphatase, and N-terminal propeptide of type 1 procollagen; younger age of menopause; a family history of osteoporosis; and higher baseline trochanteric BMD. Baseline BTMs were not predictive of 24-month BMD response to therapy. The strongest associations were for changes in BTMs with treatment.

CONCLUSION

In groups of patients, short-term changes in markers of bone turnover appear to be predictors of longer term BMD response and nonresponse to bisphosphonate therapy.

The Val432Leu polymorphism of the CYP1B1 gene is associated with differences in estrogen metabolism and bone density

Polymorphisms of the CYP450 genes that encode for the enzymes that metabolize estrogen are linked to hormone-related cancers. We investigated the impact of two polymorphisms of the CYP1B1 gene previously reported to be associated with hormone-related disorders on estrogen metabolism and bone mineral density (BMD), another hormone-dependent condition, in women from different ethnic backgrounds. Four hundred sixty-eight postmenopausal Caucasian women, 220 from St. Louis, MO, USA (mean age=63.5+/-0.53 years) and 248 from Palermo, Italy (mean age=72.9+/-0.44 years) participated in the study. Measurements of urinary estrogen metabolites by enzyme-linked immunoassay, serum estradiol by ultrasensitive radioimmnunoassay, and serum sex hormone-binding globulin by immunoradiometric assay were performed only in the American women, while BMD by dual energy X-ray absorptiometry and genotyping by pyrosequencing were performed in both American and Italian women. Differences in the levels of metabolites, free estradiol index and BMD were analyzed by analysis of covariance. Analysis among the American participants for the Valine432Leucine polymorphism showed that, compared to women with the Val/Val genotype, women with the Leu allele (Val/Leu and Leu/Leu) had significantly higher log-transformed values of total urinary estrogen metabolite (ng/mg-creatinine) levels (1.23+/-0.04, 1.35+/-0.02, and 1.34+/-0.03; p=0.03), and significantly lower BMD (gm/cm(2)) in the lumbar spine (1.009+/-0.02, 0.955+/-0.01 and 0.931+/-0.02; p=0.03) and the femoral neck (0.748+/-0.02, 0.717+/-0.01 and 0.693+/-001, p=0.03) for the Val/Val, Val/Leu and Leu/Leu genotypes respectively. There were no significant differences in the urinary metabolites and BMD in the different genotypes for the Alanine119Serine polymorphism among the American women. Meanwhile, a separate analysis among the Italian women revealed no significant differences in BMD among the different genotypes for the two polymorphisms investigated. In conclusion, women with the Leu allele for the CYP1B1 Val432polymorphism have increased estrogen catabolism, as indicated by higher urinary estrogen metabolites, compared to those with Val/Val genotype. This may lead to relative hypoestrogenism and lower BMD in the lumbar spine and femoral neck in these women. Our data suggest that through its effect on the rate of estrogen catabolism, the Val432Leu polymorphism of the CYP1B1 gene may represent as a possible genetic risk factor for osteoporosis in American women.

Deleterious effect of late menarche on distal tibia microstructure in healthy 20-year-old and premenopausal middle-aged women

Late menarche is a risk factor for fragility fractures. We hypothesized that pubertal timing-dependent alterations in bone structural components would persist from peak bone mass to menopause, independent of premenopausal bone loss. We studied the influence of menarcheal age (MENA) on femoral neck BMD (FN aBMD) by DXA and microstructure of distal tibia by HR-pQCT in healthy young adult (YAD; 20.4 +/- 0.6 [SD] yr, n = 124) and premenopausal middle-aged (PREMENO; 45.8 +/- 3.4 yr, n = 120) women. Median of MENA was 13.0 +/- 1.2 and 13.1 +/- 1.7 yr in YAD and PREMENO, respectively. In YAD and PREMENO (n = 244), FN aBMD (R = -0.29, p = 0.013), as well as total volumetric BMD (Dtot; R = -0.23, p = 0.006) and cortical thickness (Ct.Th; R = -0.18, p = 0.011) of distal tibia were inversely correlated to MENA. After segregation by the median of MENA in EARLY and LATE subgroups, the significant influences of both MENA (p = 0.004) and chronological age (p < 0.0001) were observed for FN aBMD and trabecular bone volume fraction of the distal tibia with similar differences in T-scores between LATE and EARLY subgroups in YAD (-0.36 and -0.31 T-scores) and PREMENO (-0.35 and -0.42 T-scores) women. Ct.Th was negatively influenced by MENA, whereas trabecular thickness (Tb.Th) was negatively influenced by chronological age. There was a striking inverse relationship between cross-sectional area and Ct.Th (R = -0.57, p < 0.001). In conclusion, the negative influence of late menarcheal age at weight-bearing sites as observed by the end of skeletal growth remains unattenuated a few years before menopause and is independent of premenopausal bone loss. Alterations in both bone mineral mass and microstructural components may explain the increased risk of fragility fractures associated with later menarcheal age.

Change in bone mineral density and its determinants in pre- and perimenopausal Chinese women: the Hong Kong Perimenopausal Women Osteoporosis Study

This 30-month study investigating bone change and its determinants in 438 perimenopausal Chinese women revealed that the fastest bone loss occurred in women undergoing menopausal transition but maintenance of body weight and physical fitness were beneficial for bone health. Soy protein intake also seemed to exert a protective effect.

INTRODUCTION

This 30-month follow-up study aims to investigate change in bone mineral density and its determinants in Hong Kong Chinese perimenopausal women.

METHODS

Four hundred and thirty-eight women aged 45 to 55 years were recruited through random telephone dialing and primary care clinic. Bone mass, body composition, lifestyle measurements were obtained at baseline and at 9-, 18- and 30-month follow-ups. Univariate and stepwise multiple regression analyses were performed with the regression coefficients of BMD/C (derived from baseline and follow-up measurements) as the outcome variables. Menopausal status was classified as pre- or postmenopausal or transitional.

RESULTS

Menopausal status was the strongest determinant of bone changes. An annual bone loss of about 0.5% was observed among premenopausal, 2% to 2.5% among transitional, and about 1.5% in postmenopausal women. Multiple regression analyses, revealed that a positive regression slope of body weight was protective for follow-up bone loss at all sites. Number of pregnancy, soy protein intake and walking were protective for total body BMC. Higher baseline LM was also protective for neck of femur BMD.

CONCLUSION

Maintenance of body weight and physical fitness were observed to have a protective effect on for bone loss in Chinese perimenopausal women.

Influence of age at menarche on forearm bone microstructure in healthy young women

BACKGROUND

Shorter estrogen exposure from puberty onset to peak bone mass attainment may explain how late menarche is a risk factor for osteoporosis. The influence of menarcheal age (MENA) on peak bone mass, cortical, and trabecular microstructure was studied in 124 healthy women aged 20.4 +/- 0.6 (sd) yr.

METHODS

At distal radius, areal bone mineral density (aBMD) was measured by dual-energy x-ray absorptiometry, and volumetric bone mineral density (BMD) and microstructure were measured by high-resolution peripheral computerized tomography, including: total, cortical, and trabecular volumetric BMD and fraction; trabecular number, thickness, and spacing; cortical thickness (CTh); and cross-sectional area (CSA).

RESULTS

Median MENA was 12.9 yr. Mean aBMD T score of the whole cohort was slightly positive. aBMD was inversely correlated to MENA for total radius (R = -0.21; P = 0.018), diaphysis (R = -0.18; P = 0.043), and metaphysis (R = -0.19; P = 0.031). Subjects with MENA more than the median [LATER: 14.0 +/- 0.7 (+/-sd) yr] had lower aBMD than those with MENA less than the median (EARLIER: 12.1 +/- 0.7 yr) in total radius (P = 0.026), diaphysis (P = 0.042), and metaphysis (P = 0.046). LATER vs. EARLIER displayed lower total volumetric BMD (315 +/- 54 vs. 341 +/- 56 mg HA/cm(3); P = 0.010), cortical volumetric BMD (874 +/- 49 vs. 901 +/- 44 mg HA/cm(3); P = 0.003), and CTh (774 +/- 170 vs. 849 +/- 191 microm; P = 0.023). CTh was inversely related to CSA (R = -0.46; P < 0.001). In LATER reduced CTh was associated with 5% increased CSA.

CONCLUSIONS

In healthy young adult women, a 1.9-yr difference in mean MENA was associated with lower radial aBMD T score, lower CTh without reduced CSA, a finding compatible with less endocortical accrual. It may explain how late menarche is a risk factor for forearm osteoporosis.

The assessment of osteoporosis risk factors in Iranian women compared with Indian women

BACKGROUND

Osteoporosis is an important public health problem in older adults. It is more common in postmenopausal women and not only gives rise to morbidity but also markedly diminishes the quality of life in this population. There is lack of information about the risk factor of osteoporosis in developing countries. In this study we aimed to assess the risk factors for osteoporosis in postmenopausal women from selected BMD centers of two developing Asian countries (Iran and India).

METHODS

This study is a multicenter interview-based study conducted in selected hospitals and health centers from urban areas in Iran and India. The case group included postmenopausal osteoporotic women who were identified as patients with bone density higher than 2.5 SD below average of young normal bone density (in L1-L4) spine region interest and/or total femoral region) by using DEXA method. The controls were chosen from postmenopausal women with normal bone density (in L1-L4 spine and total femoral regions using DEXA method) matching in age groups was strategy of choice.The sample sizes included from Iran a total of 363 subjects (178 osteoporotic and 185 normal) and from India a total of 354 subjects (203 osteoporotic and 151 normal).

RESULTS

The significant (p < 0.05) risk factors in present study population with their Odds Ratios (in parenthesis, respectively in Iran and India) were as follow:Lower education defined as less than class 12 or nil college (2.1) (2.7), duration of menopause greater than 5 years: (2.2) (1.4), Menarche age (after 14 years): (1.9) (1.6), Menopause age (before 45 years): (1.1) (2), Parity more than 3: (1.1) (1), Bone and joint problem (2.3) (2.2). Calcium supplementation (0.6) and HRT (0.4) were shown as protective factors and steroid therapy (3.3) was found as a risk factor in Iran. Calcium supplementation more than 1 year (0.3) was shown as a protective factor in India.Pure vegetarianism: (2.2) and Red meat consumption more than 4 times per week (1.4) was shown as a risk factor in Indian and Iranian subjects respectively. Regular consumption of Soya (0.3), almond (0.5), fish (0.5), fruits (0.4) and milk tea 4 cups per day and more (0.4) appeared to be significant protective factors in India. Regular consumption of cheese (0.5), milk (0.5), chicken (0.4), egg (0.6), fruit (0.4), tea 7 cups per day and more (0.3) were found to be significant protective factors in Iran. Exercises were shown as protective factor in Iran (0.4) and India (0.4). There were no significant differences in association of risk factors and osteoporosis between Iranian and Indian subjects.

CONCLUSION

Osteoporosis in Iranian and Indian subjects also appears to be associated with several known risk factors that well described in the literature. There were no significant differences in association of risk factors and osteoporosis between Iranian and Indian subjects. It was shown a protective role of certain nutritional dietary components and also exercises in both populations and can be exploited in preventive educational strategies on osteoporosis in these populations.

The association of common polymorphisms in the QPCT gene with bone mineral density in the Chinese population

Evidence of the linkage of chromosome 2p to bone mineral density (BMD) has previously been reported in multiple populations. However, the identification of the BMD quantitative trait loci (QTL) gene at chromosome 2p remains a challenge. We performed a gene-wide and tag single nucleotide polymorphism (SNP)-based association study of four positional and functional candidate genes (CALM2, CYP1B1, QPCT, and POMC) in a sample of 1,243 cases and matched controls. Thirteen HapMap tag SNPs were selected and genotyped by using the high-throughput Sequenom genotyping platform. Binary logistic regression analyses were performed to test for associations between each SNP genotype and BMD. Haplotype association analyses were performed by WHAP. The rs3770748 within the QPCT gene showed a significant association with spine BMD in both single-marker (P = 0.002) and haplotype association analyses (P = 0.0482 for the global test; P = 0.00092 for the haplotype-specific test). Subgroup analysis revealed that the effect was primarily driven by an association in the postmenopausal women, presumably suggesting that the rs3770748 affects postmenopausal bone loss rather than peak bone mass. Our results suggest that QPCT may be the QTL gene at chromosome 2p for spine BMD variation in the Chinese population.

Osteoporosis

Effective therapies are available for the patient who has arthritic osteoporosis. The approach is critical to ensure an optimal quality of life in these individuals who suffer with a disease that is clearly treatable.

Effects of dietary calcium compared with calcium supplements on estrogen metabolism and bone mineral density

BACKGROUND

High calcium intake has been associated with both high bone mineral density (BMD) and high urinary estrogen metabolites. However, the role of dietary calcium and calcium supplements on estrogen metabolism and BMD remains unknown.

OBJECTIVE

The objective was to investigate the importance of the source of calcium intake on estrogen metabolism and BMD.

DESIGN

The average total daily calcium intake from supplements and diet, urinary estrogen metabolites, and spine and proximal femur BMD were studied in 168 healthy postmenopausal white women.

RESULTS

Women who obtained calcium primarily from the diet or from both the diet and supplements had significantly (P=0.03) lower ratios of nonestrogenic to estrogenic metabolites (2-hydroxyestrone 1/16 alpha-hydroxyestrone) than did those who obtained calcium primarily from supplements. Adjusted BMD z scores were significantly greater in the subjects who obtained calcium primarily from the diet or from both the diet and supplements than in those who obtained calcium primarily from calcium supplements at the spine (P=0.012), femoral neck (P=0.02), total femur (P=0.003), and intertrochanter (P=0.005). This difference was evident especially in those who obtained calcium primarily from the diet, whose total calcium intake was lower than that in those who obtained calcium primarily from supplements.

CONCLUSION

Calcium from dietary sources is associated with a shift in estrogen metabolism toward the active 16 alpha-hydroxyl metabolic pathway and with greater BMD and thus may produce more favorable effects in bone health in postmenopausal women than will calcium from supplements.

Estrogen metabolism modulates bone density in men

Estrogen is a critical hormone for bone homeostasis in men, but no information is available on the role of estrogen metabolism among men. The aim of this study was to evaluate the effect of estrogen hydroxylation on male bone mineral density (BMD). Participants consisted of 61 healthy Caucasian males (mean age 66.6 +/- 1.0 years). Urinary estrogen metabolites were measured by enzyme-linked immunosorbent assay, serum estradiol by ultrasensitive radioimmunoassay, sex hormone binding globulin by radioimmunoassay, and BMD of the lumbar spine and the proximal femur by dual-energy X-ray absorptiometry. Active estrogen metabolites, 16alpha-hydroxyestrone (16alphaOHE(1)) and estriol (E(3)), positively correlated with adjusted BMD in all regions of the proximal femur (all P < 0.05) but not at the lumbar spine, and those in the highest tertile of urinary 16alphaOHE(1 )had the highest BMD. Free estradiol index (FEI) also positively correlated with BMD of the total hip, femoral neck, and intertrochanter (all P < 0.05), while there was no correlation between BMD with inactive metabolites (2-hydroxyestrone and 2-methoxyestrone) and serum testosterone. Multiple regression analysis showed 16alphaOHE(1), FEI, and body mass index are important independent predictors of BMD in all regions of the proximal femur. Estrogen metabolism may modulate BMD in men. Increased urinary 16alphaOHE(1) and E(3) levels are associated with high BMD at the proximal femur, and 16alphaOHE(1) appears to be a major determinant of BMD among the metabolites evaluated.

Lower bone mineral content in hypertensive compared with normotensive overweight Latino children and adolescents

BACKGROUND

In adults, hypertension has been shown to be inversely correlated with bone mineral content (BMC); however, the association between blood pressure (BP) and BMC has not been studied in pediatrics.

METHODS

Total body BMC of 187 overweight (mean BMI = 28.7 kg/m(2)) Latino children and adolescents (mean age = 11.2 years) were measured using dual-energy x-ray absorptiometry. Seated systolic BP (SBP) and diastolic BP (DBP) were measured using a standard mercury sphygmomanometer. Hypertension was defined by SBP or DBP above the 90(th) percentile for height, age, and sex.

RESULTS

Partial correlations revealed an inverse association between SBP and BMC (r = -0.24, P = 0.02) in boys (n = 105); results were nonsignificant (P = 0.27) in girls (n = 82). There were no significant correlations between DBP and BMC. When BMI and insulin sensitivity were adjusted for, hypertensive boys (n = 21) had lower BMC (1435 v 1636 g; P = 0.03) than normotensive boys (n = 84); similarly, hypertensive girls (n = 25) had lower BMC (1438 v 1618 g; P = 0.02) than normotensive girls (n = 57). In postpubertal adolescents (Tanner stage 4-5; n = 48), inverse correlations were stronger (r = -0.40, P = 0.007); results were nonsignificant in prepubertal and pubertal children (Tanner stage 1-3; n = 139, P = 0.57). In postpubertal girls (n = 37), there were no significant correlations (P = 0.14); inverse correlations in postpubertal boys (n = 11) became markedly stronger (r = -0.80, P = 0.02).

CONCLUSION

Based on the study findings, SBP is inversely correlated with BMC in overweight adolescents; additionally, hypertensive subjects have lower adjusted means of BMC than normotensive subjects. These promising new findings suggest that hypertension may be a risk factor for osteopenia in overweight children and adolescents; this risk may be exacerbated in postpubertal boys.

Osteoporosis in the elderly with chronic kidney disease

Considering the aging dialysis population of today, increasing our knowledge about the nature, diagnosis and the treatment of bone mineral density (BMD) problems in end-stage renal disease (ESRD) patients deserves more attention. Osteoporosis is basicly defined as a decrease in bone mass. Large epidemiological studies in general population have identified several risk factors for osteoporosis including advancing age, female gender, white race, decreased calcium intake, gastric acid suppression therapy, sedentary lifestyle, premature loss of gonadal function, decreased estrogen secretion, thin body habitus, decreased physical activity, cigarette smoking, alcohol abuse, excess glucocorticoid exposure, and possibly some genetic factors. Osteoporosis in ESRD patients is only a part of a wider spectrum of metabolic bone problems, namely uremic osteodystrophy. Therefore, its diagnosis, management and follow-up may differ from the general population and an individualization of diagnosis and definition for dialysis population may be necessary. However, standard diagnostic tools such as dual energy X-ray absorptiometry (DEXA) have been widely used for the assessment of bone mineral deficiency status in ESRD patients. Regardless of the methods, most of the studies are in concordance with a reduced BMD in HD and PD patients. Dialysis patients are known to be at increased risk for low-trauma fractures. Thinning of cortical bone, which is responsible for the largest contribution toward reduced bone mineral content in chronic renal failure results in increased fracture risk. In either normal population and dialysis patients, fracture risk is increased with age. But in dialysis patients, besides age, several other factors may also affect the degree of bone mineral deficiency, and age-BMD relationship may be blunted. Female sex, in hemodialysis patients is negatively associated with total hip BMD. While several studies have been unable to demonstrate any association between BMD and PTH levels, larger body size has been shown to have a significant positive effect on BMD in both hemodialysis and peritoneal dialysis patients. Although they have been used in small groups of chronic kidney disease (CKD) and ESRD patients, because of their potential nephrotoxicity and hypocalcemic effects, use of biphosphonates in renal patients is questionable. Currently, bone biopsy, in order to exclude adynamic bone disease is recommended before beginning treatment with bisphosphonates in chronic kidney disease and dialysis patients.

Estrogen in men: effects on bone accrual, maintenance and prevention of bone loss

Sex steroid hormones play an important role in the maintenance of bone mass in males as well as in females. Even though androgens represent the major sex steroid class in men, their primacy in regulating male skeletal remodeling has been questioned increasingly as direct and indirect evidence has emerged suggesting that estrogens also play a major role in male skeletal health. This review summarizes clinical and experimental evidence that estrogens are essential for bone accrual in the growing skeleton, maintenance of bone mass and prevention of bone loss in men.

Osteoporosis in otherwise healthy perimenopausal and early postmenopausal women: physical and biochemical characteristics

Population studies have shown that about 3-5% of perimenopausal women already have osteoporosis according to the WHO definition of osteoporosis for postmenopausal women ( t -score<or=-2.5). In general, this bone loss arises from well-characterized diseases or conditions that affect acquisition of peak bone mass and/or the rate of bone loss after peak bone mass has been attained. However, there often remains a subset of these women, with no identifiable cause of bone loss. This group has so far been little studied. We prospectively evaluated a group of 60 perimenopausal and early postmenopausal women (mean age 52.2+/-2.5 years) who were found to have apparently unexplained low bone mass, and we compared them to 120 controls matched for age and menopausal status. These women were extensively investigated, including by detailed questionnaire and laboratory testing. Of the 60 women with osteoporosis, only three were found to have previously undiagnosed disorders (two with subclinical hyperthyroidism and one with elevated serum PTH levels) that might have contributed to their low bone mass. On the other hand, osteoporotic patients were characterized by a significantly lower body weight, higher prevalence of personal and parental histories of fractures and a higher level of bone turnover as assessed by increased serum osteocalcin and bone alkaline phosphatase levels and urinary type I collagen C-telopeptide (CTX) excretion, as compared to controls. These findings support theories of a genetic contribution to osteoporosis and underline the predictive value of a previous history of personal and familial fracture in the identification of osteoporosis in early postmenopausal women.

Bone mineral density in Norwegian premenopausal women

The aims of this study were: 1) to determine bone mineral density (BMD) in different age groups, 2) to determine the prevalence of low BMD, and 3) to determine the possible association between BMD and a number of risk factors in Norwegian premenopausal women. BMD of the lumbar spine (L(2)-L(4)), total body, and the hip (total femur, femur neck, and trochanter) were measured using dual-energy X-ray absorptiometry (Prodigy, Lunar) in 145 randomly selected women aged 13-39 years. Information on other factors thought to influence BMD was obtained through questionnaire and a clinical interview. The group aged 25-29 years had the highest mean BMD in the total body, lumbar spine, and total femur while the group aged 13-19 years had the highest mean BMD in the femur neck and the trochanter. The mean BMD values of Norwegian premenopausal women were 3.4-5.1% higher than US/European reference data (P<0.05). Five percent of the study sample aged 20-39 years were defined with low BMD (Z-score <-2) using the standard values from this study. Weight-bearing physical activity, body weight, body height, and age were positively associated with BMD, whilst menstrual dysfunction and previous pregnancy were associated with lower BMD in some of the measurement sites. The results show that the factors associated with BMD are extensive, and the strategies to prevent low BMD have to be multifactorial. A follow-up study should be conducted on the study sample to investigate actual mean BMD values and BMD changes through time.

Osteoporosis

Bone is a complex organ which contains an organic matrix which serves as scaffolding, includes mineral as calcium distributed in a pattern providing structure and serves as an ion reservoir for the body. Throughout life it dynamically changes in response to changes in activity, body mass, and weight bearing. It is important to define patients at risk for bone loss, since accrued bone loss leading to osteoporosis in the older population of both men and women is unacceptable. There are many different therapies including biphosphonates which can decrease loss of bone and decrease fracture risk in patients who already have had sustained a fracture. Newer therapies such as parathyroid hormone may improve the fracture risk even more than biphosphonates over a shorter period of time.

Increased 2-hydroxylation of estrogen in women with a family history of osteoporosis

Recent studies indicate that women with predominant estrogen metabolism through the 2-hydroxyl (inactive) pathway have lower bone mineral density (BMD) compared with those with predominant 16alpha-hydroxylation (active). Although many factors have been identified to affect estrogen metabolism, the role of a family history of osteoporosis remains unknown. The objective of this study was to investigate the influence of family history of osteoporosis and other clinical factors on estrogen hydroxylation. This was a cross-sectional study conducted in a university-based research center from May 2002 to February 2004. The participants included 175 otherwise healthy postmenopausal women at least 1 yr from the last menstrual period. Main outcome measures were urinary estrogen metabolites and BMD of the spine and femur. Women with a family history of osteoporosis had significantly higher log-transformed ratios of 2-hydroxyestrone/16alpha-hydroxyestrone (0.303 +/- 0.03 vs. 0.226 +/- 0.03; P = 0.04) and 2-methoxyestrone/16alpha-hydroxyestrone (0.024 +/- 0.02 vs. -0.036 +/- 0.02; P = 0.03) compared with women without family history. As expected, these women also had significantly lower BMD at the total femur, trochanter, and intertrochanter. Surprisingly, calcium intake positively correlated with metabolite levels, and women in the highest quartile of calcium intake had the highest levels of urinary metabolites. In conclusion, women with a positive family history of osteoporosis have predominant estrogen metabolism through the inactive 2-hydroxyl pathway; thus, the increased risk of osteoporosis in those with family history may in part be related to inherited differences in estrogen metabolism. The finding that calcium intake modulates estrogen hydroxylation has never been reported and thus deserves additional investigation.

Effect of CYP1A1 gene polymorphisms on estrogen metabolism and bone density

In this study, we evaluated the effect of polymorphisms of the CYP1A1 gene, linked to hormone-related cancers, on estrogen metabolism and BMD. We found that variants carrying the A allele (CA and AA) for the C4887A polymorphism have a significantly higher degree of estrogen catabolism and lower femoral BMD.

INTRODUCTION

Polymorphisms of the CYP1A1 gene, one of the key enzymes that metabolize estrogen, have been linked with hormone-related cancers. We investigated the impact of these polymorphisms on estrogen metabolism and BMD, which is another hormone-dependent health issue.

MATERIALS AND METHODS

One hundred seventy postmenopausal women (mean age, 63.5 +/- 0.6 years) participated in the study, but analysis was limited to 156 white women. Genotyping was performed by restriction fragment length polymorphism analysis, urinary estrogen metabolites by enzyme immunoassay, serum estradiol by ultrasensitive radioimmunoassay, serum sex hormone-binding globulin by immunoradiometric assay, and BMD by DXA. Differences in the levels of urinary metabolites and BMD among the different variants were analyzed by analysis of covariance, whereas differences in free estradiol index, urinary N-telopeptide of type 1 collagen (NTx), and bone size were compared by one-way ANOVA.

RESULTS

We found that subjects carrying the A allele (CA or AA) for the C4887A polymorphism of the CYP1A1 gene have significantly lower free estradiol index (0.323 +/- 0.08 versus 0.506 +/- 0.04; p = 0.04; pmol/nmol) and higher levels of total urinary estrogen metabolites (ng/mg Cr) than CC subjects (27.92 +/- 2.03 versus 21.15 +/- 1.04; p = 0.03), suggestive of an accelerated estrogen catabolism in these (CA + AA) individuals. They also had significantly lower BMD (g/cm2) in all regions of the femur than subjects with the CC genotype, (total hip: 0.809 +/- 0.02 versus 0.865 +/- 0.01; neck: 0.671 +/- 0.02 versus 0.722 +/- 0.01; trochanter: 0.614 +/- 0.02 versus 0.656 +/- 0.01; and intertrochanter: 0.969 +/- 0.03 versus 1.039 +/- 0.01; all p < 0.05). No significant effect of this gene polymorphism was detected on lumbar spine BMD. Urinary NTx, a marker for bone resorption, was also significantly higher in the CA + AA compared with the CC variants (186.09 +/- 16.15 versus 124.00 +/- 11.87 nmol of bone collagen equivalent/mmol of creatinine; p = 0.003). Genotype frequencies for this polymorphism showed CC as the most common genotype (127/156), followed by CA (28/156), whereas AA was rare (1/156).

CONCLUSION

Women with the A allele seem to have increased estrogen catabolism, as indicated by higher urinary estrogen metabolites and lower free estradiol index. This is associated with increased bone resorption and lower femoral BMD in those with the A allele. Our data, therefore, suggest that, through its effect on the rate of estrogen catabolism, the C4887A polymorphism of the CYP1A1 gene may represent a possible genetic risk factor for osteoporosis.

Association of multiple nucleotide variations in the pituitary glutaminyl cyclase gene (QPCT) with low radial BMD in adult women

Correlation between 13 genetic variations of the glutaminyl-peptide cyclotransferase gene and adjusted aBMD was tested among 384 adult women. Among 13 variations with strong linkage disequilibrium, R54W showed a prominent association (p = 0.0003), which was more striking when examined among 309 elder subjects (> or =50 years; p = 0.0001). Contribution for postmenopausal bone loss was suggested.

INTRODUCTION

Alterations in homeostatic regulation of estrogen through the hypothalamus-pituitary-gonadal axis (HPG axis) importantly affect the pathogenesis of osteoporosis. Osteoporosis-susceptibility genes have been proposed in this hormonal axis, such as estrogen receptor genes and the gonadotropin-releasing hormone gene (GnRH). Here we report another example of genes: glutaminyl-peptide cyclotransferase gene (QPCT), an essential modifier of pituitary peptide hormones, including GnRH.

MATERIALS AND METHODS

Analyses of association of 13 single nucleotide polymorphisms (SNPs) at the QPCT locus with adjusted areal BMD (adj-aBMD) were carried out among 384 adult women. Linkage disequilibrium (LD) was analyzed by haplotype estimation and calculation of D' and r2. Multiple regression analysis was applied for evaluating the combined effects of the variations.

RESULTS AND CONCLUSIONS

LD analysis indicated strong linkage disequilibrium within the entire 30-kb region of the QPCT gene. Significant correlations were observed between the genotypes of the six SNPs and the radial adj-aBMD, among which R54W (nt + 160C>T) presented the most prominent association (p = 0.0003). Striking association was observed for these SNPs among the 309 subjects >50 years of age (R54W, p = 0.0001; -1095T>C, p = 0.0002; -1844C>T, p = 0.0002). Multiple regression analyses indicated that multiple SNPs in the gene might act in combination to determine the radial adj-aBMD. These results indicate that genetic variations in QPCT are the important factors affecting the BMD of adult women that contribute to susceptibility for osteoporosis. The data should provide new insight into the etiology of the disease and may suggest a new target to be considered during treatment.

Site specificity of regular health club exercise on muscle strength, fitness, and bone density in women aged 29 to 45 years

OBJECTIVE

To determine the effect of regular exercise with use of stepper or skier machines on muscle strength, cardiovascular fitness, bone mineral density, and markers of bone turnover in women aged 29 to 45 years.

SUBJECTS AND METHODS

We evaluated 14 women: 5 who used a stepper machine for at least 3 hours each week for 2 years, 4 who used a skier machine for at least 3 hours each week for 2 years, and 5 who did not exercise (controls). All women were healthy, had no history of disease or medication use known to affect bone metabolism, and had normal levels of estradiol-17beta. Differences between the exercise and control groups were analyzed with the Kruskal-Wallis test.

RESULTS

No significant differences were noted between the exercise groups and the control group with respect to age, height, total body bone mineral density, calcium intake, and metabolic bone markers. Significant differences were noted between the groups in body weight (stepper vs control, P=.03; skier vs control, P=.02), body mass index (stepper vs control, P=.03; skier vs control, P=.02), Physical Activity Score (stepper vs control, P=.009; skier vs control, P=.01), percentage body fat (stepper vs control, P=.03; skier vs control, P=.02), and maximum oxygen consumption (stepper vs control, P=.009; skier vs control, P=.009). Bilateral hip extensor strength was significantly stronger in the stepper group than in the skier group (P=.03). Grip strength was significantly stronger in the stepper group than in the skier group (right, P=.01; left, P=.049).

CONCLUSION

Although comparable health club exercises can contribute to fitness, their site-specific effect varies. Stepper machines are preferred over skier machines for improving hip extensor strength.

Bone mass of asian adolescents in China: influence of physical activity and smoking

INTRODUCTION/PURPOSE

Research addressing the role of biology and behavior on bone development during times of peak bone acquisition in adolescence is limited. The present investigation was conducted to address the influence of body composition (lean body mass, fat mass), menarche, leisure physical activity, sports team participation, smoking, and second-hand smoke on skeletal mass of a unique sample of Asian adolescents in China.

METHODS

A total of 166 girls and 300 boys (ages 12-16 yr) participated in this study. Bone mineral density (BMD) and content (bone mineral content (BMC)) of the forearm and the os calcis were measured using dual energy x-ray absorptiometry (DXA); lean body mass (LBM) and fat mass were estimated by bioelectrical impedance analysis (BIA); grip strength was measured by isometric dynamometry. Menarche, leisure physical activity, sports team participation, and active and passive smoking were determined using questionnaire.

RESULTS

In girls, a total of 44% of the variance in forearm BMC was attributed to a model which included LBM (32%), time since menarche (10%), and age (2%); heel BMC was best predicted by LBM alone (42%), with no significant contribution by other variables. In boys, a total of 39% of the variance in forearm BMC was attributed to a model which included LBM (28%), age (5%), sports team participation (4%), height (1%), and fat mass (1%); heel BMC was best predicted by LBM (50%) and height (3%), accounting for 53% of the variance.

CONCLUSION

The findings of this study suggest that lean body mass is the primary determinant of bone mass in Chinese adolescents. Menarche is also an important contributor in girls, whereas age and sports team participation are secondary predictors of bone mass in boys.

Association of a Trp16Ser variation in the gonadotropin releasing hormone signal peptide with bone mineral density, revealed by SNP-dependent PCR typing

Osteoporosis is believed to result from interplay among multiple environmental and genetic determinants, including factors that regulate bone mineral density (BMD). Among those factors, adequate estrogen is essential for achievement of peak bone mass as well as for postmenopausal maintenance of skeletal homeostasis. Gonadotropin-releasing hormone (GnRH) from the hypothalamus is the primary determinant in the hypothalamic-pituitary-gonadal feedback system. In genetic studies of 384 postmenopausal Japanese women, we found a significant association between BMD and an amino acid variation (Trp16Ser) located within the signal peptide of GnRH (r = 0.143, P = 0.005). These results were achieved by genotyping all subjects using a newly developed SNP-dependent PCR method. This automated, high-throughput, and inexpensive procedure is suitable for typing large numbers of samples. BMD was lowest among 16Ser/Ser homozygotes, highest among 16Trp/Trp homozygotes, and intermediate among heterozygotes. A case-control study involving 125 osteoporosis patients and 92 healthy controls revealed a significant association between the presence of a 16Ser GnRH allele and affected status (chi(2) = 4.74, P = 0.041). The results suggested that variation of the GnRH signal peptide may be an important risk factor for postmenopausal osteoporosis.

Low peak bone mineral density in healthy Lebanese subjects

Osteoporosis is a major public health problem in Western countries and is projected to have a similar impact in the Middle East. It has been suggested that peak bone mineral density (BMD), a major determinant of osteoporotic fractures later in life, may be lower in this part of the world compared with the Western world. However, subjects have not been randomly selected or systematically screened to rule out secondary causes of bone loss. The purpose of this study was to determine peak bone mass and lifestyle risk factors for bone loss in a randomly chosen sample of healthy Lebanese subjects from the greater Beirut area. Subjects 25-35 years of age were randomly selected from greater Beirut, which comprises one third of the Lebanese at large, and studied during the Fall of 1999. BMD was measured at the lumbar spine, hip, forearm, and total body. A questionnaire on lifestyle factors was administered to all subjects. Results were compared with the database of subjects from the USA provided by the manufacturer, and to the NHANES database for the total hip. Two hundred thirteen subjects were studied; 45 subjects rotated at all three centers for cross-calibration purposes. Peak BMD in Lebanese subjects was 0.2-0.9 SD below that of peak BMD in American subjects, depending on skeletal site, gender, and densitometer. These differences persisted after attempting to adjust for body size. Osteoporosis and osteopenia were more prevalent than in healthy young Americans. Height, weight, and total body fat were the most significant correlates of BMD/bone mineral content (BMC), accounting for 0.3-0.7 of the variance in bone mass measurement. Lifestyle factors had a very modest but significant contribution to bone mass variance. This is the first population-based study from the Middle East demonstrating that peak BMD is slightly lower in Lebanese subjects compared as with an established database from the USA. Due to the selection of relatively healthier subjects in our study than in the NHANES study, the actual differences between the two populations may be even greater. The impact of our findings on the epidemiology of osteoporotic fractures in Lebanon remains to be determined.

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.

Genetics of osteoporosis: role of steroid hormone receptor gene polymorphisms

Osteoporosis is a common skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. In the past years, twin and family study have shown that this disease recognizes a strong genetic component and that genetic factors play an important role in regulating bone mineral density (BMD). While in few isolate conditions osteoporosis can be inherited in a simple Mendelian pattern, due to single gene mutations, in the majority of cases has to be considered a multifactorial polygenic disease in which genetic determinants are modulated by hormonal, environmental and nutritional factors. Given the important role that steroid hormones play in bone cell development and in the maintenance of normal bone architecture, polymorphisms at receptor of the steroid/thyroid hormone receptor superfamily, such as estrogen receptor alpha (ERalpha) and Vitamin D receptor (VDR) have been thoroughly investigated in the last years and appeared to represent important candidate genes. The individual contribution of these genetic polymorphisms to the pathogenesis of osteoporosis remains to be universally confirmed and an important aim in future work will be to define their functional molecular consequences and how these polymorphisms interact with each other and with the environment to cause the osteoporotic phenotype. A further promising application of genetic studies in osteoporosis comes from their pharmacogenomic implications, with the possibility to give a better guidance for therapeutic agents commonly used to treat this invalidating disorder or to identify target molecules for new therapeutic agents.

Estrogen replacement therapy and female athletes: current issues

Physicians commonly recommend estrogen replacement as treatment for exercise-associated amenorrhoea. While the evidence shows that the basis of the amenorrhoea is estrogen deficiency, it is not clear that it is the only factor in the development of lowered bone density found in oligo-amenorrhoeic female athletes. Nutritional factors, significant in the development of the reproductive dysfunction, could also contribute to bone loss. No randomised, controlled studies of estrogen replacement in athletes have been published. However, one nonrandomised study of a small group of athletes does suggest that there are significant gains in bone density to be made by the initiation of estrogen therapy. More research is clearly needed.

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.

High density lipoproteins (HDL) in women with postmenopausal osteoporosis: a preliminary study

OBJECTIVE

Since a previous study showed an inverse correlation between high density lipoproteins (HDL) and bone mineral density (BMD), we searched for a possible relationship between HDL level and the presence of postmenopausal osteoporosis.

DESIGN

We measured HDL levels in 37 women with postmenopausal osteoporosis, and compared them with a control group of 43 healthy postmenopausal women. The HDL levels were compared between the two groups using Student's t test and were correlated with BMD by Pearson's coefficient. To avoid possible selection bias, we compared patients and controls for body mass index by chi 2 test. The sensitivity and specificity of HDL level higher than 65 mg% (positive test) or lower than 45 mg% (negative test) was compared with double emission x-ray absorptiometry (considered the gold standard in the measurement of BMD).

RESULTS

The level of HDL was significantly higher in the osteoporotic patients than in the controls (67.7 +/- 15.5 mg% vs 58.3 +/- 11.6 mg%, p = 0.0039). HDL was inversely correlated with BMD (r = -0.29, p = 0.0083). HDL higher than 65 mg% has a high specificity (77%) for patients with osteoporosis, while HDL lower than 45 mg% has a high sensitivity (97%) in detecting subject without osteoporosis.

CONCLUSIONS

Our preliminary data suggest an interesting, as yet unexplained association between HDL and bone mineral density in postmenopausal women.