Monitoring alendronate therapy for osteoporosis

Week-by-week changes in serum levels of bone-related circulating microRNAs and bone turnover markers

MicroRNAs are involved in post-transcriptional regulation of gene expression. Due to their regulatory role, microRNAs are differently expressed during specific conditions in healthy and diseased individuals, so microRNAs circulating in the blood could be used as diagnostic and prognostic biomarkers for various diseases and conditions. We want to investigate the variability of circulating microRNAs and bone turnover markers in weekly time intervals in older women. In a single-site longitudinal study, a panel of 19 bone-related miRNAs was measured using the osteomiR RT-qPCR assay in serum samples of 35 postmenopausal women divided into 3 groups: healthy controls (n = 12), low BMD (n = 14), and vertebral fractures (n = 9). Blood samples for measurement of CTX, PINP, OC, and bone ALP were collected once per week for 8 weeks at 9:00 AM after overnight fasting. Serum samples from all participants were analyzed for 19 microRNA bone biomarkers and 4 bone turnover markers over 8 weeks. We analyzed the data using a mixed model analysis of variance and found no significant changes between week-by-week time points in any of the groups. To estimate intraindividual variability between weekly time points, we have calculated the median coefficient of variation (CV). This was between 28.4% and 80.2% for microRNA, with an assay CV of 21.3%. It was between 8.5% and 15.6% for bone turnover markers, with an assay CV of 3.5% to 6.5%. The intraindividual variability was similar between groups. Circulating microRNAs measured in serum had a higher weekly intraindividual variability than bone turnover markers due in part to a higher assay CV.

RANK signaling in osteoclast precursors results in a more permissive epigenetic landscape and sexually divergent patterns of gene expression

Background

Sex is an important risk factor in the development of osteoporosis and other bone loss disorders, with women often demonstrating greater susceptibility than men. While variation in sex steroids, such as estradiol, accounts for much of the risk, there are likely additional non-endocrine factors at transcriptional and epigenetic levels that result in a higher rate of bone loss in women. Identification of these factors could improve risk assessment and therapies to preserve and improve bone health.

Methods

Osteoclast precursors were isolated male and female C57Bl/6 mice and cultured with either MCSF alone or MCSF and RANKL. Following the culture period RNA was isolated for RNA sequencing and DNA was isolated for tagmentation and ATAC sequencing. RNA-Seq and ATAC-seq were evaluated via pathway analysis to identify sex- and RANKL-differential transcription and chromatin accessibility.

Results

Osteoclasts demonstrated significant alterations in gene expression compared to macrophages with both shared and differential pathways between the sexes. Transcriptional pathways differentially regulated between male and female cells were associated with immunological functions with evidence of greater sensitivity in male macrophages and female osteoclasts. ATAC-Seq revealed a large increase in chromatin accessibility following RANKL treatment with few alterations attributable to sex. Comparison of RNA-Seq and ATAC-seq data revealed few common pathways suggesting that many of the transcriptional changes of osteoclastogenesis occur independently of chromatin remodeling.

Bone Turnover Markers and Osteokines in Adolescent Female Athletes of High- and Low-Impact Sports Compared With Nonathletic Controls

This study examined differences in resting concentrations of markers of bone formation and resorption, and osteokines between female adolescent (12-16 y) swimmers, soccer players, and nonathletic controls. Resting, morning blood samples were obtained after an overnight fast from 20 swimmers, 20 soccer players, and 20 nonathletic controls, matched for age. carboxyl-terminal cross-linking telopeptide of type I collagen (CTX), amino-terminal propeptide of type I collagen (P1NP), total osteocalcin (OC), sclerostin, osteoprotegerin (OPG), and receptor activator of nuclear factor kappa B ligand (RANKL) were analyzed in serum. After controlling for percent body fat, there were no significant differences between swimmers and nonathletic controls in any of the measured markers. In contrast, soccer players had significantly higher P1NP (89.5 [25.6] ng·mL-1), OC (57.6 [22.9] ng·mL-1), and OPG (1052.5 [612.6] pg·mL-1) compared with both swimmers (P1NP: 66.5 [20.9] ng·mL-1; OC: 24.9 [12.5] ng·mL-1; OPG: 275.2 [83.8] pg·mL-1) and controls (P1NP: 58.5 [16.2] ng·mL-1; OC: 23.2 [11.9] ng·mL-1; OPG: 265.4 [97.6] pg·mL-1), with no differences in CTX, sclerostin, and RANKL. These results suggest that bone formation is higher in adolescent females engaged in high-impact sports like soccer compared with swimmers and controls.

Change in Bone Mineral Density in Stroke Patients with Osteoporosis or Osteopenia

We aimed to investigate the correlation between changes in bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN) and osteoporosis-related factors in stroke patients with osteoporosis or osteopenia, and we suggest the need for active rehabilitation treatment. This study included 63 osteoporosis and 34 osteopenia patients who underwent a BMD test following primary stroke onset. The osteoporosis group was followed up with a BMD test after 12 months of bisphosphonate treatment, and the osteopenia group was followed up without medication. The correlation between BMD changes and functional factors was analyzed, biochemical markers were measured, and hematology tests were performed. In the osteoporosis group, a significant increase was observed in LS BMD (p < 0.05), and in the osteopenia group, there was a significant decrease in FN BMD (p < 0.05). The group with a functional ambulatory category of 1 or more showed a significant improvement in BMD (p < 0.05). Comparative analysis was performed on various indicators, but no significant correlation was found between any variable. In stroke patients with osteoporosis or osteopenia, early appropriate drug treatment is important to prevent bone loss and reduce the risk of fractures, and comprehensive rehabilitation treatment, such as appropriate education and training to prevent falls, is essential.

Potential Usefulness of BMD and Bone Turnover Monitoring of Zoledronic Acid Therapy Among Women With Osteoporosis: Secondary Analysis of Randomized Controlled Trial Data

We aimed to compare the clinical validity and the detectability of response of short-term changes in bone mineral density (BMD; hip and spine) and bone turnover markers (serum PINP and CTX) through secondary analysis of trial data. We analyzed data on 7765 women with osteoporosis randomized to 5-mg once-yearly infusions of zoledronic acid or placebo in the Health Outcomes and Reduced Incidence with Zoledronic Acid Once Yearly Pivotal Fracture Trial (HORIZON-PFT; trial ran from 2002 to 2006) and the first extension trial (trial ran from 2006 to 2009). We assessed the clinical validity and detectability of response for 1-year measurements of the following monitoring tests: total hip and lumbar spine BMD, serum N-terminal propeptide of type I collagen (sPINP), and serum C-telopeptide of type I collagen (sCTX; 6-month measurement used). Clinical validity was assessed by examining prediction of clinical fracture in Cox models; detectability of response to treatment was assessed by the ratio of signal to noise, estimated from the distributions of change in zoledronic acid and placebo groups. Baseline measurements were available for 7683 women with hip BMD, 558 with spine BMD, 1246 with sPINP, and 517 women with sCTX. Hip BMD and sPINP ranked highly for prediction of clinical fracture, whereas sPINP and sCTX ranked highly for detectability of response to treatment. Serum PINP had the highest overall ranking. In conclusion, serum PINP is potentially useful in monitoring response to zoledronic acid. Further research is needed to evaluate the effects of monitoring PINP on treatment decisions and other clinically relevant outcomes. © 2016 American Society for Bone and Mineral Research.

Preliminary Report on the Investigation of the Association Between BPPV and Osteoporosis Using Biomarkers

OBJECTIVE

To test the hypothesis that levels of a BPPV biomarker, otolin-1, correlate with those of osteoporosis markers, aminoterminal propeptide of protocollagen type I (P1NP), and aminoterminal telopeptides of collagen (NTX), thus further supporting a link between the two diseases.

STUDY DESIGN

Prospective pilot clinical trial (Level of Evidence: 2b).

PATIENTS

Postmenopausal women with BPPV.

INTERVENTIONS

Diagnostic.

MAIN OUTCOME MEASURES

Serum levels of otolin-1, P1NP, NTX, vitamin D, and calcium were examined in relation to each other, age, and DEXA scan T-scores.

RESULTS

There was a strong, negative correlation between T-scores and otolin-1 levels. Although P1NP and NTX levels were strongly correlated, neither had statistical correlations with otolin-1.

CONCLUSIONS

Despite a strong correlation between DEXA scan results and otolin-1 levels, there were no significant correlations between otolin-1 and P1NP or NTX. This suggests that the association between osteoporosis and BPPV is complex, but not likely to be causal. Although more work is needed to elucidate these relationships, this preliminary finding has important practical implications for BPPV in that proactive management of osteoporosis, per se, would not be expected to have benefits in management of BPPV.

Association between alendronate, serum alkaline phosphatase level, and heterotopic ossification in individuals with spinal cord injury

CONTEXT/OBJECTIVE

Only sparse evidence exists regarding the effectiveness of oral alendronate (ALN) in the prevention of heterotopic ossification (HO) in patients with spinal cord injury (SCI). The objective of this study is to investigate the protective effect of oral ALN intake on the appearance of HO in patients with SCI.

STUDY DESIGN

Retrospective database review.

SETTING

A Spinal Cord Unit at a Rehabilitation Hospital.

PARTICIPANTS

Two hundred and ninety-nine patients with SCI during acute inpatient rehabilitation.

INTERVENTIONS

Administration of oral ALN.

OUTCOME MEASURES

The incidence of HO during rehabilitation was compared between patients with SCI receiving oral ALN (n = 125) and patients with SCI not receiving oral ALN (n = 174). The association between HO and/or ALN intake with HO risk factors and biochemical markers of bone metabolism were also explored.

RESULTS

HO developed in 19 male patients (6.35%), however there was no significant difference in the incidence of HO in patients receiving oral ALN or not. The mean odds ratio of not developing versus developing HO given ALN exposure was 0.8. Significant correlation was found between abnormal serum alkaline phosphatase (ALP) levels and HO appearance (P < 0.001) as well as normal serum ALP and ALN intake (P < 0.05).

CONCLUSION

Even though there was no direct prevention of HO in patients with SCI by oral ALN intake, abnormal serum ALP was found more frequently in patients with HO development and without oral ALN intake. This evidence could suggest that ALN may play a role in preventing HO, especially in patients with acute SCI with increasing levels of serum ALP.

Evaluation of urinary N-telopeptide of type I collagen measurements in the management of osteoporosis in clinical practice

We measured urinary N-telopeptide of type I collagen (U-NTX) to monitor response to bisphosphonates for osteoporosis. Decrease in U-NTX was associated with increase in spine bone density. A lesser response in U-NTX was more likely in those with secondary osteoporosis or with poor compliance. U-NTX may be a useful early indicator of treatment non-compliance or secondary osteoporosis.

INTRODUCTION

This study aims to determine the utility of the bone resorption marker, U-NTX, in the clinical setting, to monitor the response to bisphosphonate therapy (alendronate and risedronate) for osteoporosis.

METHODS

A retrospective evaluation of data collected as part of the bone turnover marker monitoring service in the Metabolic Bone Centre, Sheffield, UK. Treatment compliance, underlying causes of osteoporosis, change in U-NTX/creatinine (Cr) at 4 months and change in spine and hip bone mineral density (BMD) by dual-energy X-ray absorptiometry were recorded. Treatment response was defined as either a change in U-NTX/Cr greater than a pre-defined least significant change (LSC) of 54 % or to within the lower half of a pre-defined pre-menopausal reference interval (≤ 30 nM BCE/mmol Cr).

RESULTS

A greater decrease in U-NTX/Cr at 4 months was associated with a greater increase in spine BMD at 18 months (r = -0.33; P < 0.0001, Pearson's correlation). The mean U-NTX/Cr at 4 months was higher in patients with secondary osteoporosis compared with those with primary osteoporosis (P < 0.01, ANOVA). A lesser response in U-NTX/Cr increased the likelihood of secondary osteoporosis or poor treatment compliance (P = 0.04, Fisher's exact test). A lack of response in U-NTX/Cr to within the lower half of the reference interval was a better indicator of secondary osteoporosis and treatment non-compliance than a change in U-NTX/Cr greater than LSC.

CONCLUSIONS

Treatment monitoring using U-NTX/Cr has a place in clinical practice for the early identification of non-compliance or presence of secondary osteoporosis.

Upper gastrointestinal tract transit times of tablet and drinkable solution formulations of alendronate: a bioequivalence and a quantitative, randomized study using video deglutition

The bioequivalence and upper digestive tract transit time of a drinkable solution of 70 mg/100 mL alendronate was compared to reference tablets. A randomized, single- dose, two-way crossover study of the rate of urinary recovery of alendronate during 36 h (AE((0-36 h))) by HPLC, in 104 healthy young male volunteers, showed that AE((0-36 h)) and the maximum excretion rate (R (max)) were within the accepted range of bioequivalence 81.8-105.7 and 81.7-106.2, respectively. To characterize the oesophageal passage time of the two alendronate formulations, we performed a randomized, controlled study, in 24 healthy men and women (mean 52 years old), who took the formulations standing or lying down, by an X-ray video deglutition system. When taken in the standing position, both formulations had equal mean transit times from mouth to stomach and tablet disintegration but data dispersion was significantly smaller with the liquid form. When taken in lying position, drinkable alendronate had shorter and less variable median transit times compared to the tablets. These results show that the drinkable alendronate formulation is bioequivalent to the tablets and may be advantageous in patients in whom the transit or disintegration of the tablets is impaired.

Bone turnover markers: use in osteoporosis

Biochemical markers of bone turnover (bone turnover markers, BTMs) can be used to study changes in bone remodelling in osteoporosis. Investigators and clinicians should be aware of the appropriate sample collection and storage conditions for optimum measurements of these markers. Improvements in the variability of BTM measurements have resulted from the development of assays for automated analysers, and from international consensus regarding their use. Appropriate reference intervals should be used for the optimum interpretation of results. BTMs can provide information that is useful for the management of patients with osteoporosis, for both the initial clinical assessment and for guiding and monitoring of treatment. BTMs are clinically useful to determine possible causes of secondary osteoporosis by identifying patients with high bone turnover and rapid bone loss. In the follow-up of treatment response, BTM levels respond rapidly to both anabolic and antiresorptive treatments. BTM changes can also be used for understanding the mechanism of action of drugs in development and identifying the correct dose; they are also potentially useful as surrogate biomarkers for fracture.

Reduction of urinary levels of N-telopeptide correlates with treatment compliance in women with postmenopausal osteoporosis receiving alendronate

OBJECTIVE

The aim of this study was to assess the factors associated with the effectiveness of treatment with alendronate (ALN) quantified by a reduction in urinary excretion of N-telopeptide (NTx).

METHODS

The study is an observational, prospective, multicenter trial, with a 6-month follow-up. Postmenopausal osteoporotic women (densitometric criteria), who initiated treatment with ALN (70 mg/weekly) without previous treatment with antiresorptive agents (12 month) and calcitonin (6 month), were included. The assessment of NTx levels (nmol bone collagen equivalents/mmol creatinine) in the urine was performed at baseline and after completion of follow-up. A logistic regression model included "achieving a reduction in urinary NTx of at least 30% (minimal clinically significant change [MCSC])" as a dichotomous dependent variable and the following as independent variables: baseline urinary NTx levels, treatment compliance, years since diagnosis of menopause, ALN treatment duration, and treatment with calcium and vitamin D. Treatment compliance was assessed as the percentage of days of medication prescribed as a function of the time between the beginning and end of treatment. Good compliance was defined as a percentage between 80% and 120%.

RESULTS

The variables that reached statistical significance were baseline urinary NTx values (odds ratio, 1.052; 95% CI, 1.025-1.079) and compliance (odds ratio, 3.9; 95% CI, 1.5-10.1). Therefore, the women with good treatment compliance were almost 4 times more likely to achieve an MCSC in NTx levels, and the raise in one unit of urinary NTx baseline values increased by 5% of the probability of achieving MCSC.

CONCLUSIONS

Treatment with ALN (70 mg/week) in women with postmenopausal osteoporosis effectively reduces the urinary excretion of the bone turnover biomarker NTx. The probability of achieving a clinically significant reduction is greater in those women with higher baseline levels of NTx and in women who comply with treatment.

Effects of 3 years of lasofoxifene treatment on bone turnover markers in women with postmenopausal osteoporosis

The aims of this study were to describe the changes in bone turnover markers (BTMs) in response to lasofoxifene therapy; to describe the changes in BTMs in the individual; and to examine the relationships between BTM levels on treatment and treatment outcomes. Women (n=1126) aged 59-80years with femoral neck or spine bone mineral density T-scores ≤-2.5 were randomized to lasofoxifene 0.25mg/d, 0.5mg/d, or placebo for 5years. We measured serum C-telopeptide of type I collagen (CTX) and serum procollagen I N-propeptide (PINP), osteocalcin, and bone alkaline phosphatase (ALP) at baseline and at 1, 3, 6, 12, 24, and 36months. Lasofoxifene therapy resulted in a decrease in the concentrations of bone resorption and bone formation markers compared with placebo; the decrease was maximal between 6 and 24months. The effect of lasofoxifene 0.5mg/d was similar to that of lasofoxifene 0.25mg/d. The decrease in bone ALP was less than the decreases in CTX, osteocalcin, and PINP. Lasofoxifene therapy 0.5mg/d resulted in BTM-defined response rates for CTX (decrease in concentration from baseline >60%), PINP (>50%), and bone ALP (>30%) of 35%, 45%, and 43% of women at month 12, respectively, compared with placebo responses of 4%, 4%, and 7%. In contrast, the increase in BMD took longer (50% responded after 36months of lasofoxifene 0.5mg/d) and was not as specific (15% of placebo group responded). Bone density change was weakly inversely correlated with change in the concentrations of BTMs. BTMs may prove useful in the monitoring of the response to lasofoxifene treatment for women with postmenopausal osteoporosis early in the course of treatment.

Current recommendations for laboratory testing and use of bone turnover markers in management of osteoporosis

Osteoporosis is a major health problem worldwide, and is projected to increase exponentially due to the aging of the population. The absolute fracture risk in individual subjects is calculated by the use of algorithms which include bone mineral density (BMD), age, gender, history of prior fracture and other risk factors. This review describes the laboratory investigations into osteoporosis which include serum calcium, phosphate, creatinine, alkaline phosphatase and 25-hydroxyvitamin D and, additionally in men, testosterone. Parathyroid hormone (PTH) is measured in patients with abnormal serum calcium to determine its cause. Other laboratory investigations such as thyroid function testing, screening for multiple myeloma, and screening for Cushing's syndrome, are performed if indicated. Measurement of bone turnover markers (BTMs) is currently not included in algorithms for fracture risk calculations due to the lack of data. However, BTMs may be useful for monitoring osteoporosis treatment. Further studies of the reference BTMs serum carboxy terminal telopeptide of collagen type I (s-CTX) and serum procollagen type I N-terminal propeptide (s-PINP) in fracture risk prediction and in monitoring various treatments for osteoporosis may help expedite their inclusion in routine clinical practice.

Bisphosphonates for postmenopausal osteoporosis

Bisphosphonates are effective in reducing bone turnover, increasing BMD and reducing fracture risk in postmenopausal women with osteoporosis. The licensed bisphosphonates exhibit some differences in potency and speed of onset and offset of action. These differences mean that different agents may be more advantageous in different situations. Uncertainties still exist around the optimum duration of treatment and treatment holidays, how best to use bisphosphonates with anabolic treatments, and the benefits of treatment in patients who do not have a BMD T-score below -2.5.

Effects of the Src kinase inhibitor saracatinib (AZD0530) on bone turnover in healthy men: a randomized, double-blind, placebo-controlled, multiple-ascending-dose phase I trial

Src is a nonreceptor tyrosine kinase thought to be essential for osteoclast function and bone resorption. We investigated the effect of the orally available Src inhibitor saracatinib (AZD0530) on bone turnover in healthy men. The study was part of a randomized, double-blind, placebo-controlled multiple-ascending-dose phase I trial of saracatinib. Fifty-nine healthy men (mean age 34.6 years) were divided into five cohorts; four with 12 subjects and one with 11 subjects, and randomized within each cohort in the ratio 3:1 to receive a single dose of saracatinib or placebo, respectively, followed 7 to 10 days later with daily doses for a further 10 to 14 days. Dosing levels of saracatinib ascended by cohort (60 to 250 mg). Markers of bone turnover were measured predose and 24 and 48 hours after the initial single dose and immediately before and 24 and 48 hours and 10 to 14 days after the final dose. Data from 44 subjects were included in the analysis. There was a dose-dependent decrease in bone resorption markers [serum cross-linked C-telopeptide of type I collagen (sCTX) and urinary cross-linked N-telopeptide of type I collagen normalized to creatinine (uNTX/Cr)]. At a dose of 250 mg (maximum tolerated dose), sCTX decreased by 88% [95% confidence interval (CI) 84-91%] and uNTX/Cr decreased by 67% (95% CI 53-77%) from baseline 24 hours after the final dose. There was no significant effect on bone formation markers. There were no significant adverse events. We conclude that inhibition of Src reduces osteoclastic bone resorption in humans. Saracatinib is a potentially useful treatment for diseases characterized by increased bone resorption, such as metastatic bone disease and osteoporosis.

A randomised, double-blinded, placebo-controlled, trial to determine the individual response in bone turnover markers to lasofoxifene therapy

Lasofoxifene is a novel selective estrogen receptor modulator that is being developed for the treatment of postmenopausal osteoporosis. Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is currently used to diagnose osteoporosis. BMD response to therapy, however, is often not apparent until at least one year following start of treatment. Biochemical markers of bone turnover may provide an early indication of BMD response in individual patients. The aims of the study were: 1) to determine the variability in bone turnover markers (BTM) to estimate a value for least significant change (LSC); 2) to determine the number of subjects with a response to lasofoxifene greater than LSC; 3) to determine the number of subjects whose bone turnover is decreased to the lower half of the reference range and 4) to evaluate the use of bone turnover markers to predict the change in bone density in response to lasofoxifene. Fifty-one postmenopausal osteopenic women, ages 55 to 77 (mean 63.7) years, were recruited with 44 women completing the 2 year follow up. Participants received either lasofoxifene (0.25 mg/d) or placebo, in a 1:1 ratio. Duplicate measurements of BTM (bone alkaline phosphatase (bone ALP), N-terminal propeptide of type I collagen (PINP), serum beta crosslinked C-telopeptides of type I collagen (sbeta-CTX), urinary crosslinked N-telopeptides of type I collagen (U-NTX)) were made at baseline and 6 months with single measurements at 4, 8 and 12 weeks. Duplicate measurements of BMD at the lumbar spine (LS), total hip (TH) and distal forearm (DF) were made by DXA at baseline, one and two years in all subjects. Almost all women (92 to 96%), treated with lasofoxifene, had a reduction in serum-based bone turnover markers greater than LSC, and 52 to 80% had serum-based bone turnover markers in the lower half of the reference range, by six months of lasofoxifene therapy. The change in mean LSBMD from baseline, was significantly greater in the lasofoxifene group compared to placebo at 1 and 2 years (+2.5% and +3.4%, respectively, P<0.0001). Change in PINP and U-NTX at 6 months correlated inversely with change in LS and TH BMD at one and two years. The use of lasofoxifene therapy leads to significant decreases in bone turnover by 4 weeks of lasofoxifene therapy as a group, with a decrease in BTM greater than LSC occurring in almost all women taking lasofoxifene by 6 months. By this time, in over half of women taking lasofoxifene, BTM reached the lower half of the reference range. Our results suggest that bone turnover markers are useful for monitoring response to lasofoxifene. Changes occur early and relate to the BMD response.

Bone turnover markers: understanding their value in clinical trials and clinical practice

While bone mineral density (BMD) by dual-energy X-ray absorptiometry is the primary method of determining fracture risk, assessing bone turnover may add valuable information for the management of patients with low bone mass. Bone turnover markers (BTMs) are used in clinical trials where they can provide essential information on the biological efficacy of osteoporosis treatments. In such population-based studies, BTMs can predict fracture risk independent of BMD. When combined with BMD, they improve the fracture risk estimate above and beyond BMD alone in postmenopausal osteoporotic women. Since changes in bone turnover after the initiation of therapy with bone resorption inhibitors occur much more rapidly than changes in BMD, treatment efficacy could, in theory, be determined within weeks of using BTMs. However, such predictive value is limited by the large biological variability of these biochemical markers, even though newer automated methods have reduced their analytical variability. Consequently, widespread adoption as a means of predicting treatment efficacy in fracture prevention for individual patients cannot yet be recommended. BTMs may be useful for monitoring adherence to antiresorptive therapy and may aid in identifying patients for whom antiresorptive therapy is most appropriate. Thus, although BTMs are currently confined to clinical research applications, further improvement in assay precision may extend their diagnostic value in clinical settings.

Low calcium intake is associated with increased bone resorption in postmenopausal Japanese women: Yokogoshi Study

Objective

Low Ca intake is common among Japanese women, but its effect on bone metabolism has not been fully elucidated. The aim of the present study was to determine the relationship between Ca intake and serum markers of bone turnover in postmenopausal Japanese women.

Design

A cross-sectional study.

Setting

A community setting.

Subjects

Subjects were 595 home-dwelling postmenopausal Japanese women. Ca intake was assessed by a validated FFQ. Serum type I collagen cross-linked N-telopeptides (NTX) and osteocalcin were measured as markers of bone turnover. The relationships between demographic characteristics, lifestyles, serum Ca, vitamin D and intact serum parathyroid hormone and bone turnover were also assessed.

Results

The average age of the subjects was 64·5 (sd 5·8) years and the mean Ca intake was 527 (sd 160) mg/d. Ca intake was significantly associated with serum NTX (P = 0·0104), but not with serum osteocalcin. Mean serum NTX concentration in the lowest quartile of Ca intake (<417 mg/d) was significantly higher than in the fourth, referent quartile. Among these Japanese postmenopausal women, very low Ca intake (less than ∼400 mg/d) was associated with increased bone resorption but not bone formation.

Conclusions

Increased bone resorption may be one mechanism by which this Ca-depleted population normalizes bone metabolism and prevents osteoporosis.

Utility of biochemical markers of bone turnover and bone mineral density in management of osteoporosis

Biochemical markers of bone turnover (bone-turnover markers) are released during bone formation or resorption and can be measured in blood and/or urine. The concentration of bone-turnover markers in serum or urine reflect bone remodeling activity and can potentially be used as surrogate markers of the rate of bone formation or bone resorption. While the diagnosis of osteoporosis is based on bone mineral density (BMD), the absolute fracture risk for a particular BMD measurement varies several fold depending on age and is also influenced by other clinical risk factors. The measurement of bone-turnover markers may be of additional value to BMD and clinical risk factors in fracture risk assessment by improving the sensitivity and specificity of prediction of future fractures. In clinical practice, bone-turnover markers may help make cost-effective treatment decisions in patients with borderline absolute risk. BMD changes following treatment cannot be detected with confidence for 12-24 months due to measurement imprecision. Bone-turnover markers, which show an early response following treatment, may be useful for monitoring therapy, identifying non-compliance and non-responders, and predicting early response to therapy. This review concludes by identifying the need for internationally agreed-upon standards for bone resorption and formation.

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.

Serum levels of TRAP5b, a new bone resorption marker unaffected by renal dysfunction, as a useful marker of cortical bone loss in hemodialysis patients

Tartrate-resistant acid phosphatase (TRAP) 5b is a new marker of bone resorption that is unaffected by renal dysfunction. The significance of TRAP5b was assessed in hemodialysis (HD) patients. Serum concentrations of TRAP5b and cross-linked N-telopeptide of type I collagen (NTX) were determined as bone resorption markers, and those of bone alkaline phosphatase (BAP) and intact osteocalcin (OC) were measured as bone formation markers in 58 HD patients. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry twice in the distal third of the radius, with a 2-year interval between measurements. Serum TRAP5b correlated significantly with BAP, intact OC, intact parathyroid hormone (PTH), and especially serum NTX. TRAP5b, NTX, BAP, and intact OC all correlated significantly with BMD at the time of the second measurement; and TRAP5b, NTX, and intact OC, but not BAP and intact PTH, correlated significantly with the annual change in BMD during the 2-year period. Among the bone markers, patients in the highest tertile for serum TRAP5b and intact OC showed the fastest rate of cortical bone loss. The sensitivity and specificity for detection of rapid bone loss were 57.9% and 76.9%, respectively, for serum TRAP5b. Measurement of serum TRAP5b, as well as intact OC, may be a clinically relevant assay for estimation of bone metabolic status in HD patients, although serum intact OC accumulates in uremic serum.

Alendronate with calcium and vitamin D supplementation is safe and effective for the treatment of decreased bone mineral density in HIV

BACKGROUND

Decreased bone mineral density (BMD) is prevalent in HIV-infected patients. Bisphosphonates are currently the mainstay of treatment for postmenopausal and male osteoporosis in HIV-uninfected individuals; however, their efficacy and safety in HIV-infected patients remains unclear.

METHODS

In this prospective, randomized, placebo-controlled multicenter trial, we studied the effectiveness of calcium and vitamin D supplementation with or without alendronate in improving BMD in HIV-infected subjects receiving stable antiretroviral therapy. Subjects with secondary causes of osteoporosis were excluded. The study was powered to detect differences of 3.5% between arms and to detect a moderate sex effect in percentage change in lumbar spine BMD. All dual-energy X-ray absorptiometry scans were analysed centrally, blinded by arm.

RESULTS

The 82 subjects enrolled were 71% men, 77% white, with a baseline median age of 48 years, CD4 cell count of 469 cells/mul, and lumbar spine t-score of less than 2.1; 91% had HIV-RNA levels less than 400 copies/ml, and 99% were taking antiretroviral drugs. Compared with calcium/vitamin D alone, alendronate plus calcium/vitamin D resulted in significant improvements in BMD at the lumbar spine, total hip, and trochanter, but not at the femoral neck, compared with baseline. There were trends towards significant increases in BMD values in the calcium/vitamin D group at the lumbar spine, total hip, and femoral neck. There were no apparent sex differences in the responses to therapy. Alendronate was well tolerated, without significant adverse events.

CONCLUSION

Once-weekly alendronate is safe and effective in the treatment of decreased BMD in HIV-infected patients.

[Laboratory evaluation of bone metabolism index using elecsys 2010.]

BACKGROUND

Bone markers can provide a prognostic information about the risk of osteoporotic fracture and are useful tools for monitoring the efficacy of antiresorptive therapy. We evaluated the analytical performance of the bone markers of Elecsys 2010 (Roche Diagnostics Corp., Indianapolis, USA).

METHODS

We evaluated the analytical performance of the Elecsys 2010 for serum parathyroid hormone (PTH), osteocalcin, and serum bone-derived degradation products of type I collagen C-telopeptide (S-CTX) using control material and patients' specimens. For the comparison studies, an immunoradiometric assay was used for PTH and an ELISA for serum osteocalcin and serum bone-derived degradation products of type I collagen N-telopeptide (S-NTX). We established the reference intervals of S-CTX and serum osteocalcin by analyzing 4569 Korean healthy subjects according to sex and age.

RESULTS

Within-run and total CV of most items were below 5% except S-CTX low level (5.42%). Elecsys 2010 showed a good linearity (r>/=0.99, P<0.01). Good correlations with other methods were found in osteolcalcin (r=0.95, P<0.01) and PTH (r=0.96, P<0.01). S-CTX showed a good correlation with S-NTX (r=0.76, P<0.01). Reference intervals of serum osteocalcin (ng/mL) and S-CTX (ng/mL) were 9.58-33.62 and 0.18-0.89, respectively, in adult male, 8.00-31.46 and 0.11-0.81 in 31-50 years old female, and 8.30-43.50 and 0.11-1.00 in 51-80 years old female.

CONCLUSIONS

Elecsys 2010 bone markers showed a satisfactory precision, linearity, and a good correlation with other methods. With its 'one system-many capabilities' features, Elecsys 2010 would be a useful tool for measuring bone metabolism indices.

Osteopenia and osteoporosis in patients with HIV: a review of current concepts

Since the advent of potent antiretroviral therapy in combination regimens, multiple epidemiologic studies have shown that osteopenia and osteoporosis are common among patients with HIV infection. However, there remain many areas of uncertainty about this potential complication, which can be confusing for the HIV clinician. This review summarizes the epidemiology, pathophysiology, suggested screening strategies, and management options of decreased bone mineral density in patients with HIV. Our aims are to review the available data, highlight controversial issues, and provide guidance for clinicians where supporting data are unavailable.

Development of an algorithm for using PINP to monitor treatment of patients with teriparatide

INTRODUCTION

Teriparatide effects are mediated via the preferential stimulation of osteoblastic activity over osteoclastic activity. Amino-terminal propeptide of type I procollagen (PINP) is an indicator of osteoblastic activity.

OBJECTIVE

Develop an algorithm using PINP as an aid in the management of patients with postmenopausal osteoporosis treated with teriparatide.

RESEARCH DESIGN AND METHODS

For inclusion in this post-hoc analysis, trials had to be investigations of teriparatide 20 microg/day in postmenopausal women with osteoporosis having measurements of PINP at 3 months and bone mineral density (BMD) at 12 months. Signal-to-noise ratio was calculated for a series of markers of bone turnover in the Fracture Prevention Trial. An algorithm was developed to monitor patients treated with teriparatide using PINP.

RESULTS

Three trials met inclusion criteria and included the Fracture Prevention, Forteo-Alendronate Comparator and Anabolic After Antiresorptive trials. PINP had the highest signal-to-noise ratio of all bone-turnover markers. Positive PINP responses defined as increases > 10 microg/L were observed in 77-79% of teriparatide- and in 6% of placebo-treated patients after 3 months of study drug. Mean lumbar spine BMD increases after 12 months of teriparatide in patients having PINP changes > 10 microg/L ranged from 8.3% to 9.5% and in patients with PINP changes < or = 10 microg/L ranged from 5.9% to 7.6%. In the algorithm, PINP is measured at baseline and after 1-3 months of therapy. Patients with PINP increases > 10 microg/L are given a positive message. Patients with PINP increases < or = 10 microg/L are assessed for adherence, teriparatide administration and storage techniques, and for the presence of medical conditions that might limit their therapeutic response, and these issues are addressed as appropriate. Patients without these issues and with PINP increases < or = 10 microg/L should be given a neutral message because BMD may significantly increase with continued therapy.

CONCLUSIONS

The PINP algorithm provides information regarding the anabolic response to teriparatide therapy and has the potential to identify patients requiring help with issues of adherence, injection technique, teriparatide storage, and medical problems limiting therapeutic responsiveness to teriparatide treatment. Data assessing the relationship of changes in PINP to fracture risk reduction are not available. We recommend physicians audit the use of the algorithm in practice so that improvements can be made.

Efficacy of oral etidronate for skeletal diseases in Japan

Etidronate is an oral bisphosphonate compound that is known to reduce bone resorption through the inhibition of osteoclastic activity. The efficacy of etidronate for involutional (postmenopausal and senile) and glucocorticoid-induced osteoporosis, as well as that for other skeletal diseases, was reviewed in Japanese patients. Cyclical etidronate treatment (200 mg or 400mg/day for 2 weeks about every 3 months) increases the lumbar bone mineral density (BMD) in patients with involutional osteoporosis and prevents incident vertebral fractures in patients with glucocorticoid-induced osteoporosis. The losses of the lumbar BMD in patients with liver cirrhosis and the metacarpal BMD in hemiplegic patients after stroke are prevented, and the lumbar BMD is possibly increased, preventing fragile fractures in adult patients with osteogenesis imperfecta type I. Furthermore, proximal bone resorption around the femoral stem is reduced and some complications may be prevented in patients who undergo cementless total hip arthroplasty. Oral etidronate treatment may also help to transiently relieve metastatic cancer bone pain followed by a decrease in abnormally raised bone resorption in patients with painful bone metastases from primary cancer sites, such as the lung, breast and prostate. Thus, oral etidronate treatment is suggested to be efficacious for osteoporosis, as well as other skeletal diseases associated with increased bone resorption, in Japanese patients. Randomized controlled trials needed to be conducted on a large number of patients to confirm these effects.

Effect of alendronate on bone mineral density in spinal cord injury patients: a pilot study

STUDY DESIGN

Prospective, randomised controlled trial.

OBJECTIVE

To evaluate the effect of alendronate on bone mineral density in chronic spinal cord injury (SCI) patients.

SETTING

University-based rehabilitation centre in São Paulo, Brazil.

METHODS

A total of 19 chronic SCI patients were evaluated, divided into a control group and an experimental group. Control group patients received 1000 mg of calcium daily, and experimental group patients received 1000 mg of calcium plus 10 mg of alendronate daily. The study duration was 6 months. In all, 12 densitometric parameters were analysed using whole-body dual-energy X-ray absorptiometry at baseline and after 6 months.

RESULTS

The experimental group presented increases in nine densitometric parameters, although statistical significance was attained in only two of those parameters. In the control group, an increase was observed in only one parameter, whereas the remaining 11 presented either no alteration or a decrease.

CONCLUSION

The use of alendronate had a positive effect on bone mineral density in SCI patients and therefore represents a potential tool for prevention and treatment of osteoporosis in this population.

Monitoring alendronate and estradiol therapy with quantitative ultrasound and bone mineral density

Few studies have compared quantitative ultrasound with bone mineral density (BMD) in monitoring response to therapy in osteoporosis. The aim of our study was to compare finger ultrasound variables and BMD for monitoring alendronate and estradiol therapy in postmenopausal women. We recruited 26 women aged 50 to 79 yr (mean: 65 yr) with osteoporosis; 18 patients received 10 mg/d of alendronate and 500 mg/d of calcium carbonate and 8 patients received 500 mg/d of calcium carbonate only. We recruited 21 hysterectomized postmenopausal women who were randomized to treatment or control. The treatment group received a 25-mg estradiol implant, which was replaced every 6 mo. The control group had a sham procedure. In the alendronate group, there were significant changes at 1 yr at the lumbar spine (p<0.05), bone transmission time (p<0.01), and pure speed of sound (p<0.001) and the changes continued into the second year. In the estradiol implant group, there were significant changes at 1 yr at the lumbar spine (p<0.001), the femoral neck (p<0.05), and the pure speed of sound (p<0.01). For alendronate, the signal-to-noise ratio was similar between the lumbar spine and bone transmission time (1.8 and 1.4) and greater than for the pure speed of sound and femoral neck (0.8 and 0.7); for estradiol, the signal-to-noise ratio was similar between the lumbar spine and femoral neck (2.0 and 1.5) and greater than for the pure speed of sound and bone transmission time (1.1 and 0.6). These results indicated that changes in finger ultrasound are similar in clinical utility to dual-energy X-ray absorptiometry measurements at the femoral neck for the monitoring of antiresorptive treatments for osteoporosis.

Acute effects of calcitonin nasal spray on serum C-telopeptide of type 1 collagen (CTx) levels in elderly osteopenic women with increased bone turnover

Salmon calcitonin is a potent inhibitor of osteoclastic activity. The effect of calcitonin in elderly women with high bone turnover at higher risk of developing osteoporosis has not been studied. To investigate acute effects of calcitonin treatment on bone resorption markers in elderly women, we conducted a randomized trial in women >65 years of age with high bone turnover assessed as urinary N-telopeptide of type-I collagen (NTx) levels 1 SD higher than mean premenopausal levels, which was irrespective of bone density. A total of 98 elderly women were randomly assigned to receive either 200 IU calcitonin nasal spray (n = 75) with calcium (500 mg) and vitamin D (200 IU) or calcium and vitamin D (n = 23) alone for 6 months. Blood and urine samples were collected at 0, 2, 4, and 6 months and analyzed for urinary NTx and serum C-telopeptide of type-1 collagen (CTx). At baseline, mean age was 72.1 +/- 4.7 (mean +/- SD) in the calcitonin group and 72.2 +/- 6 years in the control group. The spine and total hip BMD, serum PTH levels and urinary calcium/creatinine ratios were similar in both groups. Mean BMD was in the osteopenic range in both groups. Calcitonin treatment resulted in significant decreases in serum CTx levels, 2, 4 and 6 months after treatment as compared to baseline, and after 4 and 6 months as compared to controls. A maximum decrease from baseline of 33% was seen at 6 months. The urinary resorption marker, urine NTx, showed a significant decrease in the calcitonin group when compared to baseline only at the 6-month time point. Analysis of least significance change (LSC) showed that 70% of calcitonin patients were categorized as responders using serum CTx after 6 months of treatment. We conclude that 200 IU calcitonin effectively decreases bone resorption within 60 days of therapy, thus preventing further bone loss in elderly women who are at a high risk of developing osteoporosis.

Relationship between changes in biochemical markers of bone turnover and BMD to predict vertebral fracture risk

The change in BMD is a poor predictor of vertebral fracture risk after raloxifene treatment. One-year percent change in bone turnover and BMD was used to predict vertebral fracture risk. The percent change in osteocalcin was determined to be a better predictor of vertebral fracture risk than BMD.

INTRODUCTION

The association between baseline BMD and fracture risk is well understood. However, the relationship between changes in BMD and fracture risk is not well defined. It has previously been demonstrated that BMD change was a poor predictor of vertebral fracture risk in raloxifene-treated women, whereas bone turnover markers were significantly associated with fracture risk. In the current analysis, we explore the prediction of vertebral fracture risk using changes in both BMD and bone turnover.

MATERIALS AND METHODS

The Multiple Outcomes of Raloxifene Evaluation (MORE) trial was a randomized, placebo-controlled trial of 7705 women with osteoporosis treated with raloxifene 60 or 120 mg/day for 3 years. Markers of bone turnover were measured in one-third of the study population (n = 2503), and the present analyses include these women. Logistic regression models were constructed using one-year percent changes in BMD and bone turnover and relevant baseline demographics to predict the risk of vertebral fracture with pooled raloxifene therapy at 3 years. All covariates were standardized before modeling to facilitate direct comparisons between changes in BMD and bone turnover.

RESULTS AND CONCLUSION

Prevalent vertebral fracture status (p < 0.0001), baseline lumbar spine BMD (p < 0.0001), and number of years postmenopausal (p = 0.0005) were independent predictors of fracture risk in raloxifene-treated patients. Therapy-by-change in femoral neck BMD (p = 0.02) and therapy-by-change in osteocalcin (OC; p = 0.01) were also significant for all treatment groups, indicating that changes in BMD and OC have different effects on fracture risk for the placebo and pooled raloxifene groups. The final model included significant baseline variables and change in OC (p = 0.01), whereas change in femoral neck BMD was not significant. After adjustment of each significant baseline variable, the percent change in OC was better able to predict the reduction in vertebral fracture risk than the percent change in femoral neck BMD in patients treated with raloxifene.

Clinical performance of immunoreactive tartrate-resistant acid phosphatase isoform 5b as a marker of bone resorption

Previous immunoassays developed for the measurement of serum tartrate-resistant acid phosphatase (TRACP) have lacked specificity for osteoclastic TRACP, TRACP 5b, or have not shown satisfactory clinical performance. The aim of this study was to evaluate the clinical performance of a novel immunocapture activity assay for TRACP 5b, in comparison to telopeptide fragments of type I collagen. Within-subject variability and the effect of feeding on TRACP 5b and telopeptides of type I collagen were assessed in 20 healthy premenopausal women. Diurnal variation of TRACP 5b and serum beta C-terminal cross-linked telopeptide of type I collagen (sbetaCTX) was assessed in 12 healthy postmenopausal women. Renal clearance was assessed in 19 end stage renal failure patients undergoing routine haemodialysis. Response to antiresorptive treatment and calcium supplementation was assessed in osteoporotic postmenopausal women treated with alendronate and calcium (n = 16) or with calcium alone (n = 7) for 24 weeks.Within-subject variability (CVi) of TRACP 5b was 6.6%, lower than CVi of urinary and serum telopeptides. TRACP 5b decreased by 2.4 +/- 0.8%, in response to feeding (P < 0.05) compared to 7.0 +/- 2.6% to 7.9 +/- 3.7% for urinary telopeptides (P < 0.05 to < 0.01) and 8.5 +/- 1.7% to 17.8 +/- 2.6% for serum telopeptides (P < 0.0001). The amplitude of the diurnal rhythm for TRACP 5b was small compared to that of sbetaCTX, 14 +/- 4% vs. 137 +/- 14%. Haemodialysis did not have a significant effect on TRACP 5b but reduced sbetaCTX by 46 +/- 4% (P < 0.0001). In response to alendronate, TRACP 5b decreased by 39 +/- 4% compared to 49 +/- 4% to 69 +/- 5% for urinary telopeptides and 75 +/- 8% for sbetaCTX. We conclude that TRACP 5b shows an attenuated response to antiresorptive therapy in comparison with other markers of bone resorption, but that this may be offset by lower biological variability. TRACP 5b may provide useful additional information about bone resorption.

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.

Effect of feeding on bone turnover markers and its impact on biological variability of measurements

Bone turnover markers are subject to day-to-day and within-day variability, which may influence clinical interpretation. We examined the effect of fasting vs. feeding on the concentration and between-day variability of several markers. Twenty healthy premenopausal women were studied on 10 consecutive weekdays. Subjects were studied either in the fasting (no breakfast) or fed (breakfast at 08:00 h) state on alternate days, and were randomized to begin either fasting or fed. Two hour urine collections were obtained each day between 08:00 h and 10:00 h, and blood samples were collected daily at 09:00 h. The N-telopeptide cross-link of type I collagen in urine (uNTX) and serum (sNTX), the C-telopeptide in urine (uCTX) and serum (sbetaCTX), and immunoreactive free deoxypyridinoline (uifDPD) in urine were measured as resorption markers. Procollagen type I N-terminal propeptide (PINP), osteocalcin (OC), and bone alkaline phosphatase (bone ALP) were measured as formation markers. All bone formation and resorption markers were significantly lower in the fed state with the exception of bone ALP. The magnitude of the decrease ranged from 3.8 +/- 0.9% for PINP (p < 0.0001) to 17.8 +/- 2.6% (p < 0.0001) for sbetaCTX. Measurement variability was partitioned into analytical variability based on replicate assays (CV(a)) and within-subject variability (CV(i)). The CV(i) was greater (p < 0.05) for some markers in the fasting state (uifDPD, uNTX, and sNTX) but greater in the fed state for other markers (OC and sbetaCTX). In conclusion, the clinical impact of feeding vs. fasting is small with the exception of sbetaCTX; however, in clinical practice, collection of samples in the fasting state may be necessary to minimize the unpredictable effects of feeding. The mechanism of the acute effect of feeding on bone turnover remains uncertain.

Effect of simvastatin on bone markers in osteopenic women: a placebo-controlled, dose-ranging trial [ISRCTN85429598]

BACKGROUND

Hydroxymethylglutaryl coenzyme A reductase inhibitors increase new bone formation in vitro and in rodents. Results of epidemiologic analyses evaluating the association between use of these cholesterol-lowering drugs, bone mineral density and fracture have been mixed.

METHODS

Women (n = 24) with osteopenia, assessed by broad band ultrasound attenuation, were randomized to simvastatin 20 mg, 40 mg or identical-appearing placebo for 12 weeks. Fasting lipid profiles and biochemical markers of bone formation (bone-specific alkaline phosphatase) and resorption (N-telopeptides and C-terminal propeptide of type 1 collagen) were measured at baseline, 6 and 12 weeks.

RESULTS

Plasma low density lipoprotein-cholesterol concentration fell 7%, 39% (p < 0.01 vs baseline) and 47% (p < 0.01 vs baseline) after 12 weeks of treatment with placebo, simvastatin 20 mg and 40 mg, respectively. At baseline, bone marker concentrations were similar in the three treatment groups. At 6 and 12 weeks, bone marker concentrations were not different from baseline, and no significant differences in bone marker concentrations were observed between treatment groups at either 6 or 12 weeks.

CONCLUSION

Among osteopenic women, treatment with simvastatin for 12 weeks did not affect markers of bone formation or resorption.

Usefulness of biochemical markers of bone turnover in assessing response to the treatment of Paget's disease

The aim of this study was to investigate the usefulness of biochemical markers of bone turnover for monitoring treatment efficacy of Paget's disease of bone, and also to evaluate the utility of biological variation data in choosing the best markers for assessment of biochemical response to therapy. Thirty-eight patients with Paget's disease were included in a prospective study. All received 400 mg/day of oral tiludronate for 3 months. In 31 patients that completed treatment, biochemical markers were measured at baseline and at 1 and 6 months after treatment ended. In serum we determined the levels of total alkaline phosphatase (tAP), bone alkaline phosphatase (bAP), procollagen type I N-terminal propeptide (PINP), and C-terminal telopeptide of type I collagen (sCTx). Urine samples were analyzed for hydroxyproline (Hyp) and for C- and N-terminal telopeptides of type I collagen (CTx and NTx, respectively). Quantitative bone scintigraphy was performed at baseline and at 6 months after discontinuation of therapy. A ratio for monitoring response to treatment was obtained for each marker. This ratio reflected the size of treatment response of the marker in relation to the value of its critical difference. Thus, ratio values of >1 indicated a significant decrease of the marker after therapy. In addition, response to therapy was evaluated according to disease activity. Mean values of all markers of bone turnover decreased significantly after therapy. Serum bAP and PINP and urinary NTx showed the highest percentage reduction (between 58% and 68%). Furthermore, serum bAP and PINP showed the highest ratios for monitoring changes induced by treatment, followed by serum tAP and urinary NTx. sCTx and urinary CTx as well as Hyp showed mean ratios for monitoring changes of <1, indicating a low sensitivity for monitoring treatment. Patients with polyostotic disease showed a continuous decrease in mean values for all markers at 6 months from the end of therapy, whereas, in monostotic patients, there was a trend toward increased levels at this timepoint. In conclusion, serum bAP and PINP were the most sensitive markers for monitoring treatment efficacy in Paget's disease, although serum tAP and urinary NTx were also sensitive markers for monitoring changes. Data on biological variation are useful for assessing actual changes induced by treatment.

Role of biochemical markers in the management of osteoporosis

Several serum and urine biochemical markers of bone resorption and formation have been developed. Biochemical bone markers have been used as intermediate end-points in all major studies of anti-osteoporotic therapies. Bone resorption markers, in particular, may add an independent, predictive value to the assessment of bone loss and fracture risk. There are also potential advantages in monitoring anti-osteoporotic treatment in the short-term in addition to bone densitometry, to rapidly identify non-responders to therapy, or non-compliance. Despite these recent advances, until now bone markers have simply been very useful research tools, with their clinical utility being limited by intra-individual and diurnal variability. However, the probability of the true bone mineral density response to hormone replacement therapy for the individual patient may be predicted using algorithms based on a spectrum of cut-off bone marker levels with varying false positive and negative rates. Thus, the transition of biochemical bone markers into everyday clinical practice may be rapidly approaching.

Anabolic effects of rhIGF-I/IGFBP-3 in vivo are influenced by thyroid status

BACKGROUND

There are close interrelationships between hormones that regulate bone formation and protein biosynthesis. For example, growth hormone and thyroid hormones can influence plasma levels of insulin-like growth factor-I (IGF-I). A patient's status regarding hormones other than IGF-I may thus indirectly modify the efficacy of IGF-I treatment. The aim of the current study was to determine if a statistical method could be used to identify key endocrine variables controlling an individual's response to IGF-I treatment.

DESIGN

Biochemical profiles from the somatotropic, thyroid and adrenal axes were determined on two separate occasions in two different study cohorts. Each cohort was divided into four groups: placebo, low, medium and high dose of recombinant human IGF-I/IGF binding protein-3 (rhIGF-I/IGFBP-3). The relative changes in collagen C-terminal peptide (CICP) levels were explained as a function of the basal endocrine profile of each treated individual. This relationship was further examined in an experimental rat model, where undernourished rats were rendered hypothyroid by propylthiouracil and subsequently treated with rhIGF-I/IGFBP-3.

RESULTS

The results of our statistical analysis in both cohorts indicated that each subject's response to rhIGF-I/IGFBP-3 administration was controlled in part by the individual's thyroid status prior to drug administration (r = 0.78 for both cohorts). The results from the animal study revealed that IGF-I treatment stimulated muscle protein synthesis by 35 +/- 9% (P = 0.05) in euthyroid rats but not in hypothyroid rats.

CONCLUSION

The relationship between endocrine axes is not simple. An improved understanding of the interactions between neuroendocrine systems may facilitate the design of efficient drug regimens in the treatment of diseases such as osteoporosis and muscle wasting.

The role of bone turnover markers and risk factors in the assessment of osteoporosis and fracture risk

The clinical evaluation of osteoporosis in individual patients involves confirmation of the diagnosis, the investigation of secondary causes of osteoporosis and the evaluation of subsequent fracture risk. Optimum clinical assessment involves bone mineral densitometry with the treatment thresholds modified by clinical risk factors for individual patients. Bone turnover markers and clinical risk factors can be used to identify patients at risk of osteoporotic fracture and those who have secondary osteoporosis. Risk assessment should involve the evaluation of absolute rather than relative risk. Further work is required to improve the integration of clinical risk factors, bone turnover markers and bone densitometry into appropriate models to enable the assessment of the absolute risk of fracture for individual patients.

Components of biological variation of biochemical markers of bone turnover in Paget's bone disease

The aims of this study were to evaluate the components of biological variation of the new markers of bone turnover in patients with Paget's bone disease and to compare the results with data obtained in healthy subjects. Fifteen patients with Paget's disease in a stable period of the disease and 12 healthy premenopausal women were included for a 1 year follow-up study. Within- and between-subject biological variation, indices of individuality, and critical differences were evaluated for the following biochemical markers: in serum, total (tAP), and bone (bAP) alkaline phosphatases, procollagen type I N-terminal propeptide (PINP) and beta-carboxyterminal telopeptide of type I collagen (sCTx); in urine, hydroxyproline (Hyp), and amino (NTx) and beta-carboxyterminal (CTx) telopeptides of collagen type I. Serum markers of bone turnover showed lower biological variability than urinary markers. Within-subject biological variation was higher in pagetic patients than in healthy subjects for all serum markers. In both groups, bAP presented the lowest within-subject biological variation. In pagetic patients, all markers presented indices of individuality of <0.6, indicating their usefulness for patient monitoring. Critical differences were lower for serum markers than for urinary markers. Among pagetic patients, serum bAP and PINP showed the lowest critical differences with values close to 30%, whereas urinary CTx presented the highest critical differences (near 70%). Conversely, in healthy subjects, tAP was the marker with the lowest critical differences, being two-fold higher in pagetic patients. This study confirms the lower sensitivity of urinary markers to detect significant changes and indicates that data obtained on biological variations from healthy populations cannot always be extrapolated to pathological conditions. In addition, serum bAP and PINP seem to be the markers that best reflect a significant change in activity of Paget's disease.

Serum CrossLaps for monitoring the response in individuals undergoing antiresorptive therapy

The Serum CrossLaps (CTx) enzyme-linked immunosorbent assay (ELISA) is specific for a cross-linked, beta-aspartate-isomerized form of the epitope EKAHDGGR derived from the carboxyterminal telopeptide region of type I collagen alpha(1) chain. Collagen type I fragments reactive in the CTx assay are released during osteoclastic bone resorption and can be used as a measure of bone resorption activity. Our objectives were to assess the intraindividual variation of serum CTx concentration as well as the clinical value of the serum CTx assay for monitoring antiresorptive therapy in individual patients. The influence of the sampling time and fasting on the serum CTx measurements was studied with the aim of determining an optimal sampling protocol. Studies of circadian variation in serum CTx concentration in 15 postmenopausal women showed that fasting significantly reduced the average circadian variation of the marker from 36% to 8.7%. This was further supported by assessing short-term (2 weeks) intraindividual variation in ten postmenopausal women who were sampled in the morning, either fasting or nonfasting. The average short-term intraindividual coefficient of variation (CV) was 7.9% in the samples obtained from fasting women, and 14.3% in the samples obtained from nonfasting women. The long-term intraindividual biological variation was 13.4% in 44 postmenopausal women sampled every 6 months (fasting morning samples) over a 1 year period. The ability of the serum CTx assay to monitor individual responses to antiresorptive therapy was assessed in studies of the effects of hormone replacement therapy (HRT) and bisphosphonate (alendronate). Serum samples (morning fasting) were obtained from postmenopausal women treated with either bisphosphonate or HRT at baseline and then after various timepoints of therapy. Spine bone mineral density (BMD) measurements were carried out and the annual percentage change in spine BMD (alphaBMD) was calculated. Sixteen of 17 (94%) of the HRT-treated and 12 of 13 (92%) of the bisphosphonate-treated women showed a decrease in serum CTx after 6 months that was greater than the calculated least significant change (LSC) of the marker (LSC(CTx)). In contrast, only 59% of the HRT-treated and 64% of the bisphosphonate-treated women showed a response in spine BMD greater than the LSC(BMD) 0%) from women with a loss in spine BMD (alphaBMD < 0%). In conclusion, the serum CTx showed high specificity and sensitivity for monitoring individual responses to antiresorptive therapy. More than 92% of the treated women showed significant responses in serum CTx measurements after 6 months.

Biological variability of serum and urinary N-telopeptides of type I collagen in postmenopausal women

Measurement of N-telopeptides of type I bone collagen (NTX) provides a specific indicator of the current level of bone resorption. The biological intrasubject variability of NTX in urine and serum was studied in 277 postmenopausal women, mean age, 63.6 years +/- 10.2 (+/-SD) years. Second-morning void urine and serum specimens were collected at baseline and for two consecutive days to determine short-term variability (% CV). Long-term variability was determined by comparing NTX results at baseline and two consecutive months. Subjects were instructed to maintain current diet, lifestyle, and medications during the study. The median short-term %CV was 13.1% for urine NTX. This compared with 6.3% for serum NTX. Calculation of long-term %CV showed similar trends, with the %CV for NTX measured in serum (7.5%) lower than when measured in urine (15.6%). Using the least significant change (LSC) calculation, our data show that to be 90% confident that a decrease in NTX after initiation of antiresorptive therapy in an individual patient is not caused by variability alone, a 31 % decrease in urine NTX and a 14% decrease in serum NTX is required. As reported changes in NTX caused by antiresorptive therapy are greater than these calculations; our results support the use of either specimen to measure NTX to monitor the effect of therapy.

Practical clinical application of biochemical markers of bone turnover: Consensus of an expert panel

Biochemical markers of bone turnover have emerged as powerful tools to aid in managing osteoporosis. The newer bone markers have been intensively studied for more than a decade. As a result, we can now confidently report their clinical utility in assessing risk of rapid bone loss and fracture, and monitoring therapy in postmenopausal women with or at risk of osteoporosis. In this review, we will provide a comprehensive foundation for this utility. While there are still questions remaining to be answered, bone marker technology has matured to play an essential role in patient management. We will describe, in practical terms, how bone markers can be appropriately incorporated into clinical practice today.