Comparison of serum and urine assays for biochemical markers of bone resorption in postmenopausal women with and without hormone replacement therapy and in men

Association of lymphocyte subsets and cytokines with bone metabolism: a retrospective, cross-sectional study

BACKGROUND

Previous research has shown that lymphocytes and cytokines can mediate bone metabolism. This study explored the clinical association and predictive ability of lymphocytes and cytokines levels for bone metabolism.

METHODS

A total of 162 patients were enrolled in this study. The levels of N-terminal propeptide of type I procollagen (P1NP), β-collagen degradation product (β-CTX), total T lymphocytes, immature T lymphocytes, suppressor/cytotoxic T lymphocytes, helper/inducer T lymphocytes, B lymphocytes, natural killer (NK) cells, Interferon-gamma (IFN-γ), tumour necrosis factor-alpha (TNF-α), IFN-α, interleukin-1 beta (IL-1β), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and IL12p70 were evaluated. The relationship between these lymphocyte subsets and cytokines with bone metabolic status was examined and their predictive ability for bone metabolic status was assessed.

RESULTS

The principal component analysis (PCA) and correlation analysis results varied on differences in lymphocyte subsets and cytokines in various bone metabolism states. Differential analysis revealed significant differences in the absolute counts of B lymphocytes (P < 0.05), level of IL-12p70 (P < 0.05), and IL-8 (P < 0.001) at different P1NP levels. Significant differences were observed in the absolute counts of total T lymphocytes (P < 0.05), B lymphocytes (P < 0.05), the level of IL-6 (P < 0.05), the percentage of B lymphocytes (P < 0.01), and NK cells (P < 0.05) at different β-CTX levels. Furthermore, the receiver operating characteristic (ROC) curve showed that the absolute count of B lymphocytes and levels of IL-12p70 and IL-8 could be used to evaluate bone formation states, while the absolute counts of T and B lymphocytes, level of IL-6, and percentages of NK cells and B lymphocytes could be used to evaluate bone resorption states.

CONCLUSION

The bone metabolism status changed based on the lymphocyte subsets and cytokine levels. Differentially expressed lymphocytes and cytokines could be used to distinguish bone metabolism status.

Changes in bone mineral density in unconscious immobile stroke patients from the acute to chronic phases of brain diseases

Objectives

Decreased bone mineral density (BMD) is observed in immobile stroke patients. But it is not clarified yet how rapidly BMD reduction occurs or what the most influencing factor to BMD loss is.

Methods

BMDs in the lumbar vertebrae and the proximal femur of the paralyzed side were measured in 100 immobile stroke patients at 1 week (0 month), 1 month, and 2 months after admission. The levels of serum calcium, phosphorous, 25-hydroxyvitamin D, and urine cross-linked N-telopeptide of type I collagen (NTx) were also measured.

Results

The average age of patients was 75.0 ± 11.4 years (31–94 years). No BMD reduction was identified in the lumbar vertebrae in 2 months; however, BMD in the femur significantly decreased in 2 months in female patients (P < 0.05). Serum calcium and phosphorous levels remained within the normal range during hospitalization, and 25-hydroxyvitamin D value rose in 2 months. Urine NTx significantly increased in both males and females in 2 months (male: P < 0.05, female: P < 0.01).

Conclusions

While there was no significant change in lumbar spine BMD in the 2 month period of immobilization after stroke, BMD in the proximal femur showed a significant reduction, particularly in women. The differential loss of BMD in the 2 regions of interest could possibly be due to the physical forces acting on different body parts during mobilization and nutritional factors. More studies are needed with larger study samples and prolonged follow-up to check the accuracy of these observations.

Advances in bone turnover markers

Bone fragility fractures remain an important worldwide health and economic problem due to increased morbidity and mortality. The current methods for predicting fractures are largely based on the measurement of bone mineral density and the utilization of mathematical risk calculators based on clinical risk factors for bone fragility. Despite these approaches, many bone fractures remain undiagnosed. Therefore, current research is focused on the identification of new factors such as bone turnover markers (BTM) for risk calculation. BTM are a group of proteins and peptides released during bone remodeling that can be found in serum or urine. They derive from bone resorptive and formative processes mediated by osteoclasts and osteoblasts, respectively. Potential use of BTM in monitoring these phenomenon and therefore bone fracture risk is limited by physiologic and pathophysiologic factors that influence BTM. These limitations in predicting fractures explain why their inclusion in clinical guidelines remains limited despite the large number of studies examining BTM.

A phase 1 pooled PK/PD analysis of bone resorption biomarkers for odanacatib, a Cathepsin K inhibitor

To develop a framework for evaluating the resorption effects of Cathepsin K (CatK) inhibitors and to inform dose regimen selection, a pharmacokinetic/pharmacodynamic (PK/PD) model for odanacatib (ODN) was developed based upon data from Phase 1 studies. Pooled PK/PD data from 11 studies (N = 249) were fit reasonably to a population inhibitory sigmoid E_max model. Body weight on E₀ (baseline uNTx/Cr, urinary N-terminal telopeptide normalized by creatinine) and age on E_max (fractional inhibition of the biomarker response) were significant covariates for biomarker response. Simulations of typical osteoporosis patients (by age, sex and weight) indicated minimal differences between sexes in concentration-uNTx/Cr relationship. There was no evidence that regimen (daily vs. weekly dosing) influenced the PK/PD relationship of resorption inhibition for odanacatib. PK/PD models based on data from odanacatib (ODN) Phase 1 studies demonstrated that uNTx/Cr was an appropriate bone resorption biomarker for assessment of the effects of a CatK inhibitor. The models also identified the determinants of response in the PK/PD relationship for ODN (body weight on E₀ and age on E_max).

Cross-Sectional Study of four Serological Bone Turnover Markers for the Risk Assessment of Medication-Related Osteonecrosis of the Jaw

BACKGROUND

Despite the benefits related to the use of bisphosphonates and denosumab, medication-related osteonecrosis of the jaw (MRONJ) is a serious complication. The purpose of this study was to investigate the utility of 4 biochemical markers including serum c-terminal telopeptide cross-link of type I collagen (s-CTX), serum osteocalcin (s-OC), serum parathormon (s-PTH), and serum bone-specific alkaline phosphatase (s-BAP) as useful clinical tools to help assess the risk for MRONJ prior to invasive oral surgery.

MATERIALS AND METHODS

Twenty patients diagnosed with MRONJ and 20 controls who have been on antiresorptive therapies with no occurrence of MRONJ were included in this 2-arm cross-sectional study. The s-CTX, s-OC, s-PTH, and s-BAP values were measured. Mann-Whitney U test compared the s-CTX, s-OC, s-PTH, and s-BAP values of the MRONJ group and the controls (P < 0.05).

RESULTS

Lower values were observed in the MRONJ group compared with the control group for s-CTX (130.00 pg/mL versus 230.0 pg/mL; P = 0.12) and for s-OC (10.6 ng/mL versus 14.80 ng/mL; P = 0.051) both without significance and for s-BAP (0.23 μkat/L versus 0.31 μkat/L; P = 0.002) with significance. By contrast, the median s-PTH value of the MRONJ group was higher (30.65 ng/L versus 25.50 ng/L; P = 0.89), but without significance.

CONCLUSIONS

The evaluation of the 4 biochemical markers showed that only the value of s-BAP was significantly decreased in the MRONJ patients compared with the controls. Presently, because of the lack of evidence, a routine check prior to oral surgery for the risk assessment of MRONJ cannot be recommended.

Bone Turnover Markers in the Diagnosis and Monitoring of Metabolic Bone Disease

BACKGROUND

Disorders of bone metabolism, most notably osteoporosis, are highly prevalent and predispose to fractures, causing high patient morbidity and mortality. Diagnosis and monitoring of bone metabolic defects can present a major challenge as these disorders are largely asymptomatic and radiographic measures of bone mass respond slowly to changes in bone physiology.

CONTENT

Bone turnover markers (BTMs) are a series of protein or protein derivative biomarkers released during bone remodeling by osteoblasts or osteoclasts. BTMs can offer prognostic information on fracture risk that supplements radiographic measures of bone mass, but testing using BTMs has to take into account the large number of preanalytic factors and comorbid clinical conditions influencing BTM levels. BTMs respond rapidly to changes in bone physiology, therefore, they have utility in determining patient response to and compliance with therapies for osteoporosis.

SUMMARY

BTMs are a useful adjunct for the diagnosis and therapeutic monitoring of bone metabolic disorders, but their use has to be tempered by the known limitations in their clinical utility and preanalytic variables complicating interpretation.

Impact of Tai Chi exercise on multiple fracture-related risk factors in post-menopausal osteopenic women: a pilot pragmatic, randomized trial

BACKGROUND

Tai Chi (TC) is a mind-body exercise that shows potential as an effective and safe intervention for preventing fall-related fractures in the elderly. Few randomized trials have simultaneously evaluated TC's potential to reduce bone loss and improve fall-predictive balance parameters in osteopenic women.

METHODS

In a pragmatic randomized trial, 86 post-menopausal osteopenic women, aged 45-70, were recruited from community clinics. Women were assigned to either nine months of TC training plus usual care (UC) vs. UC alone. Primary outcomes were changes between baseline and nine months of bone mineral density (BMD) of the proximal femur and lumbar spine (dual-energy X-ray absorptiometry) and serum markers of bone resorption and formation. Secondary outcomes included quality of life. In a subsample (n = 16), quiet standing fall-predictive sway parameters and clinical balance tests were also assessed. Both intent-to-treat and per-protocol analyses were employed.

RESULTS

For BMD, no intent-to-treat analyses were statistically significant; however, per protocol analyses (i.e., only including TC participants who completed ≥ 75% training requirements) of femoral neck BMD changes were significantly different between TC and UC (+0.04 vs. -0.98%; P = 0.05). Changes in bone formation markers and physical domains of quality of life were also more favorable in per protocol TC vs. UC (P = 0.05). Changes in sway parameters were significantly improved by TC vs. UC (average sway velocity, P = 0.027; anterior-posterior sway range, P = 0.014). Clinical measures of balance and function showed non-significant trends in favor of TC.

CONCLUSIONS

TC training offered through existing community-based programs is a safe, feasible, and promising intervention for reducing multiple fracture risks. Our results affirm the value of a more definitive, longer-term trial of TC for osteopenic women, adequately powered to detect clinically relevant effects of TC on attenuation of BMD loss and reduction of fall risk in this population.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01039012.

Does anastrozole affect bone resorption similarly in early and late postmenopausal women?

The aim of this study was to determine whether the bone-resorption response to anastrozole differed according to initial patient age in postmenopausal women with breast cancer in a cross-sectional study. Second-morning void urines were collected for measurement of urinary cross-linked N-telopeptide of type I collagen (uNTx, corrected for creatinine and log-transformed) from postmenopausal women, 99 with breast cancer on anastrozole (ABC), 88 with newly diagnosed breast cancer (NDBC), and 137 community-dwelling healthy control (HC) women. Bone mineral density (BMD) was also measured at the lumbar spine (LS, L2-L4) and the femoral neck (FN) in the ABC group. uNTx (nanomole bone collagen equivalents/millimole creatinine) levels increased with age in HC subjects. In patients <70 years, anastrozole treatment led to a significant increase in uNTx compared with age-related HC subjects (1.74 vs. 1.55, P < 0.005). Patients >70 years showed no such increase compared to HC (1.72 vs. 1.69, nonsignificant); however, NDBC women >70 years had uNTx levels significantly lower than HC women (1.59 vs. 1.69, P < 0.05). There was no difference in uNTx levels above and below the age of 70 years in NDBC women (1.56 vs. 1.59, nonsignificant). ABC women were more likely to have a positive LS BMD z score than age-matched controls. Anastrozole treatment increases bone turnover more in younger postmenopausal women with breast cancer than in older women compared to healthy controls. Higher LS BMD in ABC patients may help protect against fracture.

Tai Chi for osteopenic women: design and rationale of a pragmatic randomized controlled trial

Background

Post-menopausal osteopenic women are at increased risk for skeletal fractures. Current osteopenia treatment guidelines include exercise, however, optimal exercise regimens for attenuating bone mineral density (BMD) loss, or for addressing other fracture-related risk factors (e.g. poor balance, decreased muscle strength) are not well-defined. Tai Chi is an increasingly popular weight bearing mind-body exercise that has been reported to positively impact BMD dynamics and improve postural control, however, current evidence is inconclusive. This study will determine the effectiveness of Tai Chi in reducing rates of bone turnover in post-menopausal osteopenic women, compared with standard care, and will preliminarily explore biomechanical processes that might inform how Tai Chi impacts BMD and associated fracture risks.

Methods/Design

A total of 86 post-menopausal women, aged 45-70y, T-score of the hip and/or spine -1.0 and -2.5, have been recruited from primary care clinics of a large healthcare system based in Boston. They have been randomized to a group-based 9-month Tai Chi program plus standard care or to standard care only. A unique aspect of this trial is its pragmatic design, which allows participants randomized to Tai Chi to choose from a pre-screened list of community-based Tai Chi programs. Interviewers masked to participants' treatment group assess outcomes at baseline and 3 and 9 months after randomization. Primary outcomes are serum markers of bone resorption (C-terminal cross linking telopeptide of type I collagen), bone formation (osteocalcin), and BMD of the lumbar spine and proximal femur (dual-energy X-ray absorptiometry). Secondary outcomes include health-related quality-of-life, exercise behavior, and psychological well-being. In addition, kinetic and kinematic characterization of gait, standing, and rising from a chair are assessed in subset of participants (n = 16) to explore the feasibility of modeling skeletal mechanical loads and postural control as mediators of fracture risk.

Discussion

Results of this study will provide preliminary evidence regarding the value of Tai Chi as an intervention for decreasing fracture risk in osteopenic women. They will also inform the feasibility, value and potential limitations related to the use of pragmatic designs for the study of Tai Chi and related mind-body exercise. If the results are positive, this will help focus future, more in-depth, research on the most promising potential mechanisms of action identified by this study.

Trial registration

This trial is registered in Clinical Trials.gov, with the ID number of NCT01039012.

Is bone quality associated with collagen age?

The World Health Organization defines osteoporosis as a systemic disease characterized by decreased bone tissue mass and microarchitectural deterioration, resulting in increased fracture risk. Since this statement, a significant amount of data has been generated showing that these two factors do not cover all risks for fracture. Other independent clinical factors, such as age, as well as aspects related to qualitative changes in bone tissue, are believed to play an important role. The term "bone quality" encompasses a variety of parameters, including the extent of mineralization, the number and distribution of microfractures, the extent of osteocyte apoptosis, and changes in collagen properties. The major mechanism controlling these qualitative factors is bone remodeling, which is tightly regulated by the osteoclast/osteoblast activity. We focus on the relationship between bone remodeling and changes in collagen properties, especially the extent of one posttranslational modification. In vivo, measurements of the ratio between native and isomerized C-telopeptides of type I collagen provides an index of bone matrix age. Current preclinical and clinical studies suggests that this urinary ratio provides information about bone strength and fracture risk independent of bone mineral density and that it responds differently according to the type of therapy regulating bone turnover.

Bone markers and their prognostic value in metastatic bone disease: clinical evidence and future directions

BACKGROUND

Bone metastases are prevalent among patients with advanced solid tumors. Metastatic bone disease alters bone homeostasis, resulting in reduced bone integrity and, consequently, increased skeletal complications. Biochemical markers of bone metabolism may meet an unmet need for useful, noninvasive, and sensitive surrogate information for following patients' skeletal health.

MATERIALS AND METHODS

Data for this review were identified by searches of PubMed, and references from relevant articles using the search terms "bone markers" or individual bone marker nomenclature, "cancer," and "metastases." Abstracts and reports from meetings were included only when they related directly to previously published work. Only papers published in English between 1990 and 2007 were included.

RESULTS

Recent retrospective analyses with bisphosphonates, and particularly with zoledronic acid, have shown significant correlations between biochemical markers of bone metabolism levels and clinical outcomes, especially for bone resorption markers. Clinical results for biochemical markers of bone formation and resorption and other emerging markers of bone metabolism including bone sialoprotein, receptor-activator of nuclear factor-kappaB ligand, osteoprotegerin, and other markers are presented. However, biochemical markers of bone metabolism are not yet an established surrogate endpoint for treatment efficacy.

CONCLUSIONS

Biochemical markers of bone metabolism may allow physicians to identify which patients with metastatic bone disease are at high risk for skeletal-related events or death and who may be responding to therapy. Prospective randomized clinical trials are underway to further assess the utility of markers of bone metabolism in patients with bone metastases.

Change in serum measurements of cartilage oligomeric matrix protein and association with the development and worsening of radiographic hip osteoarthritis

OBJECTIVE

To determine the association between changes in serum levels of cartilage oligomeric matrix protein (COMP) and serum N-telopeptide crosslinks (NTX) over a 6-year interval with the development and progression of radiographically apparent hip osteoarthritis (RHOA) in a community sample of elderly women over 8.3 years of follow-up.

METHODS

Pelvic radiographs were obtained a mean of 8.3 years apart in Caucasian women > or =65 years of age enrolled in the Study of Osteoporotic Fractures. From a cohort of 5928 subjects, we randomly sampled study subjects ( approximately 170 per group) to perform two nested case-control studies, one of RHOA incidence and the other of RHOA progression. Baseline and year 6 serum COMP and serum NTX levels were measured by enzyme linked immunosorbent assay in duplicate and percentage change in serum levels was calculated. Odds ratios (ORs) and 95% confidence intervals (CIs) for 1 standard deviation (SD) change in the serum COMP and NTX level differences were calculated using logistic regression analysis and used to predict the development or progression of RHOA, adjusting for potential covariates.

RESULTS

The percentage change in the level of serum COMP from baseline to year 6 was found to be a risk factor for the development of incident RHOA [adjusted OR of 1.58 per 1 SD increase (95% CI: 1.19-2.09)], and reduction of progression of RHOA [adjusted OR of 0.74 per 1 SD increase (95% CI: 0.58-0.96)]. Quartile analysis of serum COMP changes revealed that the three highest quartiles of change in serum COMP were associated with (1) a five-fold greater risk of developing incident RHOA [adjusted OR=5.42 (95% CI: 2.80-10.60)], and (2) a 50% decreased risk of developing progression of RHOA [adjusted OR=0.48 (95% CI: 0.30-0.80)]. No significant association was found between changes in serum NTX levels from baseline to year 6 with either incident RHOA or the progression of existing RHOA.

CONCLUSION

Measurement of serum COMP at two distinct timepoints may be a method of identifying patients at risk for developing incident RHOA and those with baseline RHOA that will not rapidly progress.

Effect of risedronate on biochemical marker of bone resorption in postmenopausal women with osteoporosis or osteopenia

OBJECTIVE

The primary objective of the present study was to evaluate the effectiveness and adverse events of risedronate use in postmenopausal woman by measuring its effects on urinary crosslinked C-terminal telopeptides of type I collagen (CTx), a biochemical marker of bone resorption.

METHODS

One hundred osteoporotic (control and treatment) and 111 osteopenic (control and treatment) postmenopausal women, selected according to World Health Organization criteria, were included in the study. The treatment groups (osteopenic and osteoporotic) were given risedronate 35 mg once a week. The primary endpoint was mean percentage change in CTx from baseline to 6 months. The secondary endpoints included evaluation of the incidence of clinical or laboratory adverse events occurring during the 6-month study period. The least significant change (LSC), calculated from the within-subject variability in the two control groups, was used to define response.

RESULTS

Of the 211 women enrolled, 157 (74.4%) completed the study. After 6 months, urinary CTx levels were -54.7% (range -67% to -48%) below baseline in the osteoporotic treatment group and -66.7% (range -74% to -59%) below baseline in the osteopenic treatment group. Analysis of LSC showed that 89% of risedronate treatment groups were categorized as responders after 6 months of treatment.

CONCLUSION

The study shows that osteoporotic and osteopenic women on risedronate treatment have statistically significant suppressed bone turnover and CTx can be useful to confirm this observation. The low withdrawal rate and adverse effects rate show that risedronate was well tolerated by the study population.

The amino- and carboxyterminal cross-linked telopeptides of collagen type I, NTX-I and CTX-I: a comparative review

Bone diseases such as osteoporosis or bone metastases are a continuously growing problem in the ageing populations across the world. In recent years, great efforts have been made to develop specific and sensitive biochemical markers of bone turnover that could help in the assessment and monitoring of bone turnover. The amino- and carboxyterminal cross-linked telopeptides of type I collagen (NTX-I and CTX-I, respectively) are two widely used bone resorption markers that attracted great attention due to their relatively high sensitivity and specificity for the degradation of type I collagen, and their rapid adaptation to automated analyzers. However, the clinical performance of both markers differs significantly depending on the clinical situation. These differences have caused considerable confusion and uncertainty. If used correctly, both markers have great potential to improve the management of many bone diseases. We here review the biochemistry, analytical background and clinical performance of NTX-I and CTX-I, as documented in the accessible literature until March 2008.

Higher efficacy of urinary bone resorption marker measurements in assessing response to treatment for osteoporosis in postmenopausal women

Osteoporosis has reached epidemic proportions. This situation has stimulated the development of biochemical markers to assist in assessing osteoporotic risk and monitoring treatment efficacy. Biochemical markers for assessing the level of bone resorption have been developed during the last few decades. One of the most widely used bone resorption markers is cross-linked N-terminal telopeptides (NTX). Measurements of urinary and serum NTX provide indications of the level of bone resorption during osteoporosis treatment. However, it remains unclear whether urinary or serum NTX measurements show better efficacy for assessing osteoporosis treatment effects during the early phase of treatment. Therefore, the primary aim of the present study was to compare the efficacies of urinary and serum NTX measurements for assessing the level of bone resorption during the early stage of osteoporosis treatment. We enrolled 43 postmenopausal Japanese women in an open-label randomized placebo-controlled trial. Overall, 21 women in the osteoporosis treatment group and 19 women in the placebo group completed the study. There was a significant reduction in urinary NTX in the treatment group, which was detectable as early as 4 weeks and maintained until 16 weeks, compared with the placebo group. On the other hand, serum NTX did not show a significant reduction in the treatment group compared with the placebo group until 16 weeks. These results indicate that urinary NTX measurements are more sensitive and show higher efficacy than serum NTX measurements for assessing treatment effect during the early phase of osteoporosis treatment in postmenopausal women.

Optimising antiresorptive therapies in postmenopausal women: why do we need to give due consideration to the degree of suppression?

Accelerated bone turnover with bone resorption exceeding bone formation is a major mechanism underlying postmenopausal bone loss and hence the development of osteoporosis. Accordingly, inhibition of bone resorption is a rational approach for the prevention of osteoporosis. In this context, the most logical option, hormone replacement therapy, reverses the rate of bone turnover to premenopausal levels, whereas the magnitude of inhibition by amino-bisphosphonates and the recently introduced anti-receptor activator of NFkappaB ligand (RANKL) antibody often exceeds this. As bone turnover has crucial implications for the continuous renewal of bone tissue, the over-suppression of bone turnover has potential consequences for bone quality and strength. Long-term treatment with potent bisphosphonates has recently been associated with osteonecrosis of the jaw and dose-dependent increases in micro-crack accumulation in animals. Although these observations are the subject of ongoing discussions, it is timely to discuss whether the over-suppression of bone turnover below premenopausal levels is really our ultimate goal when defining the success criteria for antiresorptive agents. In this review, the implications of high and excessively low bone turnover of endogenous origin for bone quality, fracture risk and integrity of the jaw are discussed. In addition, animal and clinical research revealing initial findings regarding the potential adverse effects of drug-induced suppression of bone remodeling are summarised. The inhibition of bone resorption, which is either transient between doses (e.g. with calcitonin) or does not exceed premenopausal levels (with hormone replacement therapy or selective estrogen receptor modulators), is preferable because it not only provides similar antifracture efficacy but can also assist in the maintenance of the dynamic repair of micro-cracks/micro-fractures.

Comparing raloxifene with continuous combined estrogen-progestin therapy in postmenopausal women: Review of Euralox 1

OBJECTIVES

To review the main findings of the Euralox 1 study - a multicentre, randomised, double-blind study conducted in 1008 healthy postmenopausal women allocated to raloxifene (n = 495) or continuous combined estrogen-progestin therapy (ccEPT; n = 513) for 6 months -- and provide an overview of the risks and benefits of raloxifene and ccEPT.

METHODS

A review is provided of previously published findings on uterine safety (bleeding rates and changes in endometrial thickness and uterine volume), gynaecological adjudication, cardiovascular risk (lipids, fibrinogen), adverse events, compliance, treatment satisfaction and quality of life. New data on biochemical markers of bone turnover (serum N-telopeptides and C-terminal telopeptides of type I collagen; NTX and CTX) assessed before and after 6 months' treatment are presented.

RESULTS

Raloxifene caused less uterine bleeding than ccEPT and, unlike ccEPT, did not alter endometrial thickness or uterine volume. Serum CTX and NTX levels were reduced in both treatment groups, but the reduction was significantly greater with ccEPT. The two treatments had differential effects on lipids and fibrinogen levels; raloxifene had more favourable effects on serum HDL, the LDL/HDL ratio, and plasma fibrinogen. Raloxifene was associated with fewer adverse events or discontinuations, and this was associated with higher treatment satisfaction and better self-reported compliance.

CONCLUSIONS

The clinical risk-benefit profile of raloxifene derived from the intermediate endpoints of this study suggests that it may be a better alternative to ccEPT for preventing long-term postmenopausal health risks in healthy postmenopausal women who are not suffering from vasomotor symptoms.

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

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

Prevention and treatment of postmenopausal osteoporosis

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

Bone turnover from early pregnancy to postweaning

BACKGROUND

To elucidate the sequences of changes in bone metabolism and bone density during pregnancy, lactation and postweaning.

METHODS

Women were recruited (n = 254) in early pregnancy and followed for 2 years. Markers of bone formation (osteocalcin) and resorption (NTx) were measured at five occasions. Bone mineral density (BMD) of whole-body and lumbar spine L1-L4 (DXA) and ultrasonography of os calcis were measured in a subgroup (n = 14).

RESULTS

NTx appeared bone specific in comparison to pyridinolines. NTx started to increase early in pregnancy and remained elevated during lactation (p < 0.001). Osteocalcin was low during pregnancy, but peaked during lactation (p < 0.018). The subsequent decrease was associated with time since resumption of menses (r2 = 0.23; p < 0.001). There was indication of a decrease in calcaneal bone mass during pregnancy and an evident decrease in lumbar spine (p = 0.041) and os calcis (p = 0.037) during lactation. No detectable decrease was identified in whole-body BMD (p = 0.090) during lactation, but in general, BMD was higher in whole-body (1.9%) and lumbar spine (6.6%) 18 months postpartum than during puerperium (p = 0.003).

CONCLUSION

According to the bone metabolic markers, bone resorption increased early in pregnancy and remained elevated over lactation, while bone formation increased during lactation, probably regulated by mechanisms associated with absence of menses. The high metabolic bone turnover during late pregnancy and lactation lead to a decline in cancellous bone mass during lactation, but this seemed beneficial for BMD postweaning.

Age-dependent effects of atorvastatin on biochemical bone turnover markers: a randomized controlled trial in postmenopausal women

The use of HMG-CoA-reductase inhibitors (statins) has been associated with decreased risk of bone fractures in epidemiological studies. In vitro evidence suggests that statins may stimulate bone formation, but the data are still preliminary. We assessed the effects of the HMG-CoA-reductase inhibitor atorvastatin on biochemical parameters of bone metabolism in a multicenter, randomized, double-blind, placebo-controlled trial conducted between October 2001 and October 2002 in three hospital-based outpatient metabolism clinics. Forty-nine postmenopausal women, mean age 61 +/- 5 years, mean time postmenopause 12.6 +/- 8.8 years, were treated with atorvastatin, 20 mg per day ( n=24) or matching placebos ( n=25) for 8 weeks. Comparing the differences to baseline between the groups, there were no statistically significant effects of atorvastatin either on the bone formation markers intact osteocalcin and bone-specific alkaline phosphatase or on the bone resorption markers C-telopeptide and intact parathyroid hormone. The marker of bone fractures, undercarboxylated osteocalcin, was also unchanged. When analyzed in dependence of age, atorvastatin increased C-telopeptide and osteocalcin in the younger subjects, while it decreased them in older subjects. Most interestingly, in older subjects, atorvastatin caused a significant decrease in the ratio of C-telopeptide to osteocalcin, an indicator of bone remodeling, while the ratio was increased in younger subjects, suggesting beneficial effects on bone turnover exclusively in older individuals (approx. >63 years). In summary, the present data suggest that short-term treatment with atorvastatin may have age-dependent effects on biochemical markers of bone turnover in postmenopausal women.

Comparison of the effects of calcium loading with calcium citrate or calcium carbonate on bone turnover in postmenopausal women

Calcium supplementation is known to increase bone mineral density and decrease fractures, but the relative efficacy of different forms of calcium supplementation is not established. We compared the effects of calcium carbonate and calcium citrate on markers of bone resorption in older postmenopausal women in an open-labeled crossover study. Forty women were randomized to receive 1000 mg/day of either calcium citrate or calcium carbonate for 12 weeks, followed by a 2-week washout without calcium supplements and 12 weeks treatment with the alternate calcium supplement. All women received vitamin D (900 IU/day). Thirty-four women (25 Caucasian, nine Hispanic) completed the study. No significant differences in the decrease in parathyroid hormone (PTH) or bone specific alkaline phosphatase or the increase in urinary calcium/creatinine were detected between the two treatments. However, calcium citrate supplementation decreased the collagen cross-link resorption markers, urinary N-telopeptide (-30%), C-telopeptide (-31%), free deoxypyridinoline (19%) and serum N-telopeptide (-8%), compared to no significant change following calcium carbonate supplementation (+2%, +3%, +2% and +2%, respectively; P<0.05). Calcium citrate decreased markers of bone resorption significantly more than calcium carbonate in postmenopausal women, although no differences in their effects in calcium excretion or PTH were detected.

The use of biochemical markers in osteoporosis

Osteoporosis is a skeletal disease in which there is a loss of, or de-crease in, bone mass with a deterioration of the microarchitecture of bone tissue. The disease is progressive, taking place over a period of years, and involves derangements in the processes of bone turnover. These derangements can be classified as those in which osteoclast activity (resorption) is stimulated so that more bone is re-moved than formed or in which osteoblast activity (formation) is hindered such that refilling of the resorption cavity is incomplete. Regardless of the process, a key pathologic development is the net loss of bone mass. This article reviews the use of biochemical markers in osteoporosis.

Reduction in PINP, a marker of bone metabolism, with raloxifene treatment and its relationship with vertebral fracture risk

In the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, 7705 postmenopausal women with osteoporosis, defined by low bone mineral density and/or prevalent vertebral fractures (VF), were randomized to placebo or raloxifene (60 or 120 mg/day). All women received daily calcium (500 mg) and vitamin D (400-600 IU) supplements. Our previous analyses found that changes in BMD and biochemical markers of bone turnover are poorly predictive of the reduction in VF risk observed with raloxifene. This present study evaluated the effects of raloxifene on type I procollagen N-terminal propeptide (PINP), a new marker of bone turnover. Logistic regression analysis models evaluated the relationships between the changes at 1 year in PINP, serum osteocalcin (OC), bone-specific alkaline phosphatase (BSAP), and urinary excretion of type I collagen C-telopeptide fragments normalized to creatinine (CTx/Cr), and the risk of new VF at 3 years for placebo and pooled raloxifene. A subset of 967 women (mean age = 68 years) from the MORE cohort had PINP, OC, BSAP, and CTx evaluated at baseline. Both doses of raloxifene significantly decreased (P < 0.001) all biochemical markers of bone turnover from baseline. Compared to baseline, PINP levels were decreased by medians of 11.0% and 40.8% in the placebo and pooled raloxifene groups, respectively. In addition, the placebo and pooled raloxifene groups decreased serum OC by 8.5% and 31.8%, BSAP by 15.8% and 34.6%, and urinary CTx/Cr excretion by 5.6% and 46.5%, respectively, from baseline. In the pooled raloxifene group, the logistic regression relationship between 3-year VF risk and 1-year percentage change for each biochemical marker was statistically significant with PINP (slope estimate = 0.0085, P = 0.009), OC (slope estimate = 0.0068, P = 0.035), and BSAP (slope estimate = 0.0056, P = 0.039), but not with CTx/Cr (slope estimate = 0.0027, P = 0.192). Furthermore, the percent decrease in PINP at 1 year could account for 28% of the total reduction in vertebral fracture risk. In conclusion, a 1-year decrease in PINP, BSAP, or OC, but not CTx/Cr, may be predictive of the 3-year VF risk reduction with raloxifene therapy in this subset of postmenopausal women with osteoporosis.

Different acute responses of serum type I collagen telopeptides, CTX, NTX and ICTP, after repeated ingestion of calcium

BACKGROUND

N- and C-terminal fragments of type I collagen such as NTX, CTX and ICTP are released into circulation during bone resorption and can be quantified in serum. Their respective sensitivity as indices of osteoclastic activity was compared after a short-term inhibition of resorption induced by repeated drinking of calcium-fortified water.

METHODS

Serum NTX, CTX and ICTP were measured by specific immunoassays in one group of 15 subjects sampled at 08.00, 11.00, 14.00 and 17.00 (referred to as T0, T3h, T6h and T9h) and having ingested in two experimental periods 660 ml of either low-calcium mineral water or the same low-calcium mineral water fortified with calcium (300 mg/l) at three times (08.00, 11.00 and 14.00).

RESULTS

Oral intake of calcium-fortified water resulted in progressive decrease in serum CTX (by 38.7% at T3h, 61.0% at T6h and 60.4% at T9h) and NTX (by 19.0% at T3h, 24.1% at T6h and 25.2% at T9h) while serum ICTP concentrations were not significantly affected. Since ingestion of low-calcium water induced a modest but significant decrease in both CTX (-19.4%) and NTX (-10.6%) we compared the two sets of assays with repeated-measures two-factor analysis of variance with interaction. Ingestion of calcium-fortified water vs. low-calcium water resulted in a significant decrease in both serum CTX (time, P<0.0001; treatment, P<0.0001; time-by treatment, P<0.0001) and NTX (time, P<0.0001; treatment, P=0.0001; time-by treatment, P=0.0066).

CONCLUSIONS

CTX is more sensitive than NTX while ICTP is not sensitive to calcium-induced acute changes in osteoclastic activity. The present results stress the importance of choosing appropriate biochemical bone markers to demonstrate the effects of calcium on bone resorption.

Bone turnover and body weight relationships differ in normal-weight compared with heavier postmenopausal women

Low body weight is associated with increased risk for fractures, whereas higher body weight has been shown to be protective against osteoporosis. This study evaluated whether body weight plays a role regulating bone turnover and mass in normal-weight (body mass index (BMI) <25 kg/m2), overweight (BMI 25-29.9 kg/m2) and obese (BMI> or =30 kg/m2) postmenopausal women who were either receiving hormone replacement therapy [HRT(+)] or not [HRT(-)] (total of six groups). Body weight, BMI, total body bone mineral content (TBBMC), and markers of bone formation (serum osteocalcin) and bone resorption (urinary pyridinoline (PYD) and deoxypyridinoline) were retrospectively analyzed in 210 postmenopausal women. The mean age was 67+/-6 years, with mean body weight of 70.8+/-14.2 kg, ranging from 45.0 to 115.5 kg. Body weight was positively correlated with TBBMC ( r=0.50, p<0.0001). There was a lower TBBMC and higher bone formation rate in normal-weight than obese HRT(-) women, but in women taking HRT there were no differences between BMI categories. In addition, in normal-weight HRT(-) women only, PYD and body weight showed a negative correlation (r=-0.39, p=0.01). Among normal-weight, but not overweight or obese subjects, we observed higher TBBMC and lower bone turnover in the HRT(+) compared with the HRT(-) group. Regression models explained 36% of the variance in TBBMC, mainly through body weight. Additional models could only explain 11-15% of the variance in bone turnover. Taken together, these data suggest that among normal-weight but not obese postmenopausal women, higher bone turnover is associated with lower bone mass, and that only normal-weight women show a different bone turnover profile with HRT treatment. Body weight should be considered an important factor in bone metabolism with relevant clinical implications.

The values of urinary NTx in postmenopausal women undergoing HRT; the role of additional alendronate therapy

OBJECTIVE

To determine the changes in levels of urinary NTx at the end of the 6th month of oral and transdermal hormone replacement therapy (HRT) and the effects of additional alendronate therapy for osteoporotic women.

METHOD

Of 66 postmenopausal women 23 were treated with oral estradiol+norethisterone acetate (E+P), and 22 were treated with transdermal estradiol+norethisterone acetate. The third group consisted of 21 women with osteoporosis (bone mineral density < 100 mg/cm(3)) and treated with oral E+P plus alendronate 10 mg/day.

RESULT

Significant decreases of urinary NTx levels were seen after HRT in all study groups (P < 0.05). But the decline of NTx levels was not different between the oral and transdermal HRT groups (P > 0.05). There was no additional decrease in the levels of NTx with alendronate therapy (P > 0.05) but NTx excretion diminished more in patients with high baseline levels.

CONCLUSION

The decline of NTx at the end of the 6th month of HRT reflects the decrease of bone resorption and it is not related to the route of administration.

Critical differences in the serial measurement of three biochemical markers of bone turnover in the sera of pre- and postmenopausal women

OBJECTIVES

The purpose of this investigation was to quantify the biologic, day-to-day variability and critical differences in serum levels of crosslinked collagen N-telopeptides (NTx), procollagen aminoterminal extension propeptides (PINP) and bone specific alkaline phosphatase (bAP) in healthy women.

DESIGN AND METHODS

Seven blood samples were collected from 12 pre- and 15 postmenopausal women over 4 to 6 months. NTx, PINP and bAP levels were determined utilizing enzyme- and radioimmunoassay techniques.

RESULTS

The within-subject coefficient of variation (C.V.) in serum bAP, NTx and PINP levels was 7.1, 10.6 and 12.4% respectively. These variances did not differ significantly among premenopausal women when compared with postmenopausal subjects. Combining terms for analytical and biologic variability revealed that a critical difference between 2 successive serial measurements is 24% for bAP, 34% for NTx and 38% for PINP.

CONCLUSION

Circulating levels of NTx, PINP and bAP are stable over time periods of several months, allowing for the determination of significant changes in skeletal metabolism of women.

Biochemical Markers of Bone Turnover and Response of Bone Mineral Density to Intervention in Early Postmenopausal Women: An Experience in a Clinical Laboratory

Background: Markers of bone formation and resorption may be useful as early indicators of response to therapy. Our aim in this study was to investigate the use of bone markers for monitoring of intervention for bone loss in early postmenopausal women and to assess the relationships between these markers and changes in bone mineral density (BMD).

Methods: Subjects were randomly assigned to the following groups: a control group; a group receiving calcium alone; groups receiving calcium plus low or conventional doses of conjugated equine estrogen; and groups receiving calcium plus low or conventional doses of calcitriol. At baseline and at 1 and 3 months after intervention, we measured serum intact osteocalcin, serum N-terminal midfragment osteocalcin, serum C-terminal telopeptide of type I collagen (CTx), urinary deoxypyridinoline cross-links, and urinary CTx. The BMD of the lumbar spine and the femoral neck was measured at baseline and after 1 and 2 years of intervention.

Results: No marker changed significantly in the control group except urinary CTx, which increased at 3 months. Serum CTx decreased in all regimens at 1 or 3 months of intervention. In addition, the changes of all markers at 3 months were inversely associated with the change in the BMD of the lumbar spine at 1 or 2 years (r = −0.144 to −0.314), whereas only the changes of bone resorption markers at 3 months were inversely correlated with the changes in femoral BMD at 1 or 2 years (r = −0.143 to −0.366).

Conclusions: Biochemical markers of bone turnover appear to be of use in assessing early response to therapy. Bone resorption markers, especially serum CTx, are better indicators than bone formation markers for estimating the response to intervention in early postmenopausal women. However, the early changes in bone markers were weakly related to the later changes in BMD.