Cyclic variations of bone resorption mediators and markers in the different phases of the menstrual cycle

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Menstrual Cycle Related Fluctuations in Circulating Markers of Bone Metabolism at Rest and in Response to Running in Eumenorrheic Females

This study examined potential fluctuations in bone metabolic markers across the menstrual cycle both at rest and after a 30-min bout of continuous running at 80% of V̇O_2max. Resting and post-exercise (0, 30, 90 min) sclerostin, parathyroid hormone (PTH), carboxy-terminal cross-linking telopeptide of type I collagen (β-CTXI), and procollagen type 1 N propeptide (PINP) were assessed in 10 eumenorrheic women (age: 21 ± 3 y, BMI: 23.2 ± 3.0 kg^.m²) during the mid- to late-follicular (FP: day 8.0 ± 1.4) and mid-luteal (LP: day 22.0 ± 2.5) phases of the menstrual cycle. Ovulation was determined using ovulation kits and daily measurement of oral body temperature upon awakening. Menstrual cycle phase was subsequently confirmed by measurement of plasma estradiol and progesterone. On average, resting estradiol concentrations increased from 46.3 ± 8.9 pg·mL^-1 in the FP to 67.3 ± 23.4 pg·mL^-1 in the LP (p = 0.015), and resting progesterone increased from 4.12 ± 2.36 ng·mL^-1 in the FP to 11.86 ± 4.49 ng·mL^-1 in the LP (p < 0.001). At rest, there were no differences between menstrual cycle phases in sclerostin (FP: 260.1 ± 135.0 pg·mL^-1; LP: 303.5 ± 99.9 pg·mL^-1; p = 0.765), PTH (FP: 0.96 ± 0.64 pmol·L^-1; LP: 0.79 ± 0.44 pmol·L^-1; p = 0.568), β-CTXI (FP: 243.1 ± 158.0 ng·L^-1; LP: 202.4 ± 92.3 ng·L^-1; p = 0.198), and PINP (FP: 53.6 ± 8.9 μg·L^-1; LP: 66.2 ± 20.2 μg·L^-1; p = 0.093). Main effects for time (p < 0.05) were shown in sclerostin, PTH, β-CTXI and PINP, without phase or interaction effects. Sclerostin increased from pre- to immediately post-exercise (45%; p = 0.007), and so did PTH (43%; p = 0.011), both returning to resting concentrations 30 min post-exercise. β-CTXI decreased from pre- to post-exercise (20%; p = 0.027) and was still below its pre-exercise concentrations at 90 min post-exercise (17%; p = 0.013). PINP increased immediately post-exercise (29%; p < 0.001), returning to resting concentrations at 30 min post-exercise. These results demonstrate no effect of menstrual cycle phase on resting bone marker concentrations or on the bone metabolic marker response to intense exercise.

Sex Differences in Biological Systems and the Conundrum of Menopause: Potential Commonalities in Post-Menopausal Disease Mechanisms

Sex-specific differences in biology and physiology likely start at the time of conception and progress and mature during the pre-puberty time frame and then during the transitions accompanying puberty. These sex differences are impacted by both genetics and epigenetic alterations during the maturation process, likely for the purpose of preparing for successful reproduction. For females, later in life (~45–50) they undergo another transition leading to a loss of ovarian hormone production at menopause. The reasons for menopause are not clear, but for a subset of females, menopause is accompanied by an increased risk of a number of diseases or conditions that impact a variety of tissues. Most research has mainly focused on the target cells in each of the affected tissues rather than pursue the alternative option that there may be commonalities in the development of these post-menopausal conditions in addition to influences on specific target cells. This review will address some of the potential commonalities presented by an integration of the literature regarding tissue-specific aspects of these post-menopausal conditions and data presented by space flight/microgravity (a condition not anticipated by evolution) that could implicate a loss of a regulatory function of the microvasculature in the risk attached to the affected tissues. Thus, the loss of the integration of the paracrine relationships between endothelial cells of the microvasculature of the tissues affected in the post-menopausal environment could contribute to the risk for post-menopausal diseases/conditions. The validation of this concept could lead to new approaches for interventions to treat post-menopausal conditions, as well as provide new understanding regarding sex-specific biological regulation.

The Specificities of Elite Female Athletes: A Multidisciplinary Approach

Female athletes have garnered considerable attention in the last few years as more and more women participate in sports events. However, despite the well-known repercussions of female sex hormones, few studies have investigated the specificities of elite female athletes. In this review, we present the current but still limited data on how normal menstrual phases, altered menstrual phases, and hormonal contraception affect both physical and cognitive performances in these elite athletes. To examine the implicated mechanisms, as well as the potential performances and health risks in this population, we then take a broader multidisciplinary approach and report on the causal/reciprocal relationships between hormonal status and mental and physical health in young (18-40 years) healthy females, both trained and untrained. We thus cover the research on both physiological and psychological variables, as well as on the Athlete Biological Passport used for anti-doping purposes. We consider the fairly frequent discrepancies and summarize the current knowledge in this new field of interest. Last, we conclude with some practical guidelines for eliciting improvements in physical and cognitive performance while minimizing the health risks for female athletes.

Bone metabolic marker concentrations across the menstrual cycle and phases of combined oral contraceptive use

There is a need to further understand the impact of the menstrual cycle and phase of combined oral contraceptive (COC) use on the pre-analytical variability of markers of bone metabolism in order to improve standardisation procedures for clinical practice and research. The aim of this study was to assess bone metabolism marker concentrations across the menstrual cycle and phases of COC use. Carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX), procollagen type 1 N propeptide (P1NP) and Bone alkaline phosphatase (Bone ALP) concentrations were assessed in eumenorrheic women (n = 14) during the early follicular, ovulatory and mid-luteal phases of the menstrual cycle and in COC (Microgynon®) (n = 14) users on day 2-3 of pill consumption (PC1), day 15-16 pill consumption (PC2) and day 3-4 of the pill free interval (PFI). β-CTX was significantly (-16%) lower at PC2 compared to PC1 (P = 0.015) in COC users and was not affected by menstrual cycle phase (P > 0.05). P1NP and Bone ALP were not significantly different across either menstrual cycle phase or phase of COC use (all P > 0.05). There was no difference in pooled bone marker concentrations between eumenorrheic women and COC users (P > 0.05). In contrast to some previous studies, this study showed that bone marker concentrations do not significantly fluctuate across the menstrual cycle. Furthermore, bone resorption markers are significantly affected by phase of COC use, although bone formation markers do not significantly vary by COC phase. Therefore, the phase of COC use should be considered in clinical practice and research when assessing markers of bone metabolism as this can impact circulating concentrations of bone metabolic markers yet is not currently considered in existing guidelines for best practice.

Influence of short-term ovarian stimulation on bone metabolism in women undergoing fertility treatment

Objectives

Hormonal disturbances during menopause are an established influencing factor on bone health, but the role of controlled ovarian hyperstimulation for fertility treatment remains unclear. To evaluate the influence of ovarian stimulation on bone metabolism with particular regard to serum follicle-stimulating hormone (FSH) levels this prospective observational study was conducted.

Methods

A total of 71 women underwent controlled ovarian hyperstimulation with recombinant FSH (rFSH) or human menopausal gonadotropin (HMG) (FSH + LH) administered in individual doses, with gonadotropin-releasing hormone (GnRH) agonist down-regulation initiated in the luteal phase of the previous cycle. At four time points (start of down-regulation [T1], start of ovarian stimulation [T2], oocyte retrieval [T3] and luteal phase of the stimulation cycle [T4]), luteinizing hormone (LH), FSH, estradiol (E2), osteocalcin (OC), bone-specific alkaline phosphatase (BAP), as well as the bone resorption markers β-isomerized C-terminal telopeptide of type I collagen (β-CTX) and tartrate-resistant acid phosphatase (TRACP) were measured.

Results

The cyclic variations in FSH levels had a positive effect on the concentration profile of the bone resorption marker β-CTX (p=0.0001). Supraphysiologic estradiol levels showed a negative association with osteocalcin concentrations (p=0.017), and significantly lower OC and TRACP levels were observed at T4 compared to T1. By group comparison, women treated with rFSH presented with a higher bone turnover than the HMG group at the end of a stimulation cycle (T4).

Conclusions

Our results show that FSH is a significant influencing factor of bone metabolism. Overall, there was no evidence of enhanced bone resorption under short-term ovarian stimulation therapy. Further studies with bigger sample sizes are warranted to validate these results.

Rhythmic Fluctuations in Levels of Liver Enzymes During Menstrual Cycles of Healthy Women and Effects of Body Weight

BACKGROUND & AIMS

Female sex hormones affect several non-reproductive organs, but little is known about their effects on the liver during a normal menstrual cycle. We aimed to investigate the association between sex hormones and liver enzymes in healthy menstruating women.

METHODS

We performed a post-hoc analysis of data from the BioCycle study, a longitudinal cohort study designed to determine the association of sex hormones with markers of oxidative stress during the menstrual cycle. We analyzed data collected from 259 menstruating women, over 1-2 menstrual cycles, who had as many as 16 separate office visits, timed by fertility monitors. Levels of liver enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase, and alkaline phosphatase (ALKP), bilirubin, and lipids were measured by laboratory assays.

RESULTS

We found a natural cyclic pattern for liver enzymes, with transaminases and ALKP peaking in the mid-follicular phase and reaching a trough in the late luteal phase; the peak to trough differences were 4.0 ± 4.9 U/L for ALT and 8.8 ± 4.0 U/L for ALKP. Levels of ALT were significantly and negatively associated with levels of progesterone on the preceding visit (P = 5x10^-4), whereas level of ALKP was negatively associated with level of estrogen (P = .007) and progesterone (P = 1x10^-11). Food and alcohol intake did not modify the association. The amplitude of ALT fluctuation was greater in African Americans and decreased with age. Fluctuations in levels of ALT were smaller in women with body mass indices >30 kg/m² (P = .03). During menstrual fluctuation, 49% of participants had ALT values both above and below the normal cut-off value (19 U/L).

CONCLUSIONS

Levels of liver enzymes fluctuate during the normal menstrual cycle, possibly mediated by progesterone, and the fluctuation varies with age and body mass index. These findings indicate the importance of accounting for phase of menstrual cycle when interpreting liver enzyme measurements in menstruating women.

Sex Differences in Proatherogenic Cytokine Levels

BACKGROUND

It has been shown that sex affects immunity, including cytokine production. Given that atherosclerosis is an inflammatory disease promoted by specific cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, we aimed at evaluating whether sex could affect the levels of these proatherogenic cytokines in a group of healthy adults. In this analysis, we also included other cytokines and peptides that have been implicated in atherosclerosis development and progression.

METHODS

A total of 104 healthy adults were recruited; we measured circulating levels of IL-1β, IL-6, TNF-α, angiotensins and angiotensin-converting enzyme-2 (ACE2), as well as osteoprotegerin and receptor activator of nuclear factor κB ligand (RANKL).

RESULTS

IL-1β, IL-6, and TNF-α were significantly higher in men as compared to women. They were all associated with testosterone and the testosterone/estradiol ratio. They remained significantly associated with sex (but not with hormones) after being tested for potential confounders.

CONCLUSIONS

Sex seems to influence the levels of proatherogenic cytokines. This is consistent not only with sex differences in vulnerability to infections but also with the higher cardiovascular risk exhibited by the male gender as compared to the female gender. Nevertheless, this association is only partly explained by hormone levels.

Calciphylaxis in patients with chronic kidney disease: A disease which is still bewildering and potentially fatal

Calciphylaxis, also known as calcific uraemic arteriolopathy, is a rare syndrome that typically causes skin necrosis and usually affects dialysis patients. Its pathogenesis is multifactorial and is the consequence of many factors causing ectopic calcifications in patients with chronic kidney disease, such as calcium-phosphate metabolism disorders, hyper- or hypo-parathyroidism, diabetes, obesity, systemic inflammation and the use of vitamin K antagonists, among others. From a clinical point of view, calciphylaxis may progress from painful purpura to extensive areas of skin necrosis that can potentially lead to superinfection and the death of the patient due to sepsis. Treatment is primarily based on managing the wounds, eliminating all the possible precipitating factors of ectopic calcification and administering agents which are capable of inhibiting the process of calcification.

Tai Chi Exercise for the Quality of Life in a Perimenopausal Women Organization: A Systematic Review

BACKGROUND

Improvement of the quality of life in perimenopausal women has recently become an important global health issue. Extensive research reports provide evidence of Tai Chi for the quality of life, but no systematic review has individually investigated Tai Chi as a main intervention on the quality of life in perimenopausal women.

OBJECTIVE

To assess clinical evidence of Tai Chi for the quality of life in perimenopausal women.

METHODS

Studies related to the effect of Tai Chi on the quality of life in perimenopausal women in the databases of China and abroad were searched. RevMan version 5.2 software was used, and the Medical Outcomes Study 36-item short form health survey (SF-36) and bone mineral density (BMD) were selected as evaluation indices.

RESULTS

Five trials were included. The results of this study showed that Tai Chi had a significant effect on bodily pain, general health, vitality, mental health of SF-36, and the spine dimension of BMD, as supported by the following data: bodily pain (Standard Mean Difference [SMD] = -3.63; 95% confidence interval [CI] [-6.62, -0.64]; p = .02); general health (SMD = -5.08; 95% CI [-7.60, -2.56]; p < .0001); vitality (SMD = -5.67; 95% CI [-8.54, -2.81], p = .0001); mental health (SMD = -2.51; 95% CI [-4.82, -0.20], p = .03); and spine dimension of BMD (SMD = -0.06; 95% CI [-0.10, -0.01]; p = .01). However, Tai Chi had no effect on physical function, emotional health, social function, role-physical of SF-36, and the hip dimension of BMD, as supported by the following data: physical function (SMD = -1.79; 95% CI [-5.15, 1.57]; p = .30); emotional health (SMD = -2.90; 95% CI [-7.23, 1.43], p = .19]; social function (SMD = -2.23, 95% CI [-5.08, 0.61], p = .12; role-physical (SMD = - 1.18; 95% CI [-4.84, 2.47], p = .53; and hip dimension of BMD (SMD = -0.01; 95% CI [-0.03, 0.01]; p = .31).

LINKING EVIDENCE TO ACTION

This systematic review found significant evidence for Tai Chi improving bodily pain, general health, vitality, mental health of SF-36, and the spine dimension of BMD in patients with perimenopausal syndrome. Findings suggest that Tai Chi might be recommended as effective and safe adjuvant treatment for patients with perimenopausal syndrome. More high-quality randomized controlled trials are urgently needed to confirm these results.

Changes of serum sclerostin and Dickkopf-1 levels during the menstrual cycle. A pilot study

Studies in postmenopausal women have identified sclerostin as a strong candidate for mediating estrogen effects on the skeleton. The effects of estradiol on sclerostin and Dickkopf-1 in younger women remain unclear. The main purpose of this study is to investigate the impact of estradiol and gonadotrophins fluctuations during the menstrual cycle on circulating sclerostin and Dickkopf-1 levels and the possible relationship of sclerostin and Dickkopf-1 with changes in N-terminal propeptide of type 1 collagen and C-telopeptide of collagen cross-links. Fourteen healthy premenopausal Caucasian women, with regular menses, aged 33.6 ± 4.5 years participated. After the first day of menstruation and every-other-day up to the next menses, fasting serum estradiol, luteinizing hormone, follicle-stimulating hormone, sclerostin, Dickkopf-1, N-terminal propeptide of type 1 collagen, and C-telopeptide of collagen cross-links levels were measured in peripheral blood. Participants completed dietary questionnaires and the International physical activity questionnaire during the cycle. Neither sclerostin nor Dickkopf-1 levels changed significantly across the menstrual cycle (p = 0.18 and p = 0.39, respectively), while N-terminal propeptide of type 1 collagen and C-telopeptide of collagen cross-links levels presented cyclic variation (p < 0.001 and p = 0.004, respectively). Baseline sclerostin (29.23 ± 10.62 pmol/L) positively correlated with N-terminal propeptide of type 1 collagen (r = 0.71, p < 0.01) and C-telopeptide of collagen cross-links (r = 0.63, p < 0.05), while Dickkopf-1 (4.82 ± 2.23 pmol/L) correlated positively with N-terminal propeptide of type 1 collagen (r = 0.56, p < 0.05). Mid-cycle E2 levels presented significant negative association with the percent decrease of C-telopeptide of collagen cross-links at all-time points during the luteal period (r = -0.60 to -0.68, p < 0.05-0.01). Circulating sclerostin and Dickkopf-1 levels do not change across the menstrual cycle and do not demonstrate any relationship with estradiol in premenopausal women. Further investigation is needed concerning the role of sclerostin and Dickkopf-1 on bone turnover in young estrogen-sufficient women.

Could molecular assessment of calcium metabolism be a useful tool to early screen patients at risk for pre-eclampsia complicated pregnancy? Proposal and rationale

One of the most frequent causes of maternal and perinatal morbidity is represented by hypertensive disorders during pregnancy. Women at high risk must be subjected to a more intensive antenatal surveillance and prophylactic treatments. Many genetic risk factors, clinical features and biomarkers have been proposed but none of these seems able to prevent pre-eclampsia onset. English literature review of manuscripts focused on calcium intake and hypertensive disorders during pregnancy was performed. We performed a critical analysis of evidences about maternal calcium metabolism pattern in pregnancy analyzing all possible bias affecting studies. Calcium supplementation seems to give beneficial effects on women with low calcium intake. Some evidence reported that calcium supplementation may drastically reduce the percentage of pre-eclampsia onset consequently improving the neonatal outcome. Starting from this evidence, it is intuitive that investigations on maternal calcium metabolism pattern in first trimester of pregnancy could represent a low cost, large scale tool to screen pregnant women and to identify those at increased risk of pre-eclampsia onset. We propose a biochemical screening of maternal calcium metabolism pattern in first trimester of pregnancy to discriminate patients who potentially may benefit from calcium supplementation. In a second step we propose to randomly allocate the sub-cohort of patients with calcium metabolism disorders in a treatment group (calcium supplementation) or in a control group (placebo) to define if calcium supplementation may represent a dietary mean to reduce pre-eclampsia onset and to improve pregnancy outcome.