Serial assessment of serum bone metabolism markers identifies women with the highest rate of bone loss and osteoporosis risk

Aconine attenuates osteoclast-mediated bone resorption and ferroptosis to improve osteoporosis via inhibiting NF-κB signaling

Osteoporosis (OP), a prevalent public health concern primarily caused by osteoclast-induced bone resorption, requires potential therapeutic interventions. Natural compounds show potential as therapeutics for postmenopausal OP. Emerging evidence from in vitro osteoclastogenesis assay suggests that aconine (AC) serves as an osteoclast differentiation regulator without causing cytotoxicity. However, the in vivo functions of AC in various OP models need clarification. To address this, we administered intraperitoneal injections of AC to ovariectomy (OVX)-induced OP mice for 8 weeks and found that AC effectively reversed the OP phenotype of OVX mice, leading to a reduction in vertebral bone loss and restoration of high bone turnover markers. Specifically, AC significantly suppressed osteoclastogenesis in vivo and in vitro by decreasing the expression of osteoclast-specific genes such as NFATc1, c-Fos, Cathepsin K, and Mmp9. Importantly, AC can regulate osteoclast ferroptosis by suppressing Gpx4 and upregulating Acsl4, which is achieved through inhibition of the phosphorylation of I-κB and p65 in the NF-κB signaling pathway. These findings suggest that AC is a potential therapeutic option for managing OP by suppressing NF-κB signaling-mediated osteoclast ferroptosis and formation.

Pro-Inflammatory Proteins Associated with Frailty and Its Progression-A Longitudinal Study in Community-Dwelling Women

The complex pathophysiology underlying biological aging creates challenges for identifying biomarkers associated with frailty. This longitudinal, nontargeted proteomics study aimed to identify proteins associated with frailty, particularly the change from nonfrail to frail. The population-based Osteoporosis Prospective Risk Assessment cohort includes women all of whom are 75 years old at inclusion (n = 1044) and reassessed at 80 years (n = 715) and 85 years (n = 382). A deficits in health frailty index (FI) and 92 plasma proteins (Olink CVD-II panel) were available at all ages. The identical age facilitated differentiating chronological and biological aging. Bidirectional analyses, performed cross-sectionally and longitudinally, used regression models controlled for false discovery rate (FDR), across 5- and 10-year time windows and longitudinal mixed models. Frailty outcomes were frailty index, frailty status (frail defined as FI ≥ 0.25), change in frailty index, and change in frailty status, together with protein expression or change in protein expression. Elevated levels of 32 proteins were positively associated with the FI, cross-sectionally at all ages (range: β-coefficients 0.22-2.06; FDR 0.021-0.024), of which 18 were also associated with frailty status (range: odds ratios 1.40-5.77; FDR 0.022-0.016). Based on the accrued data, eight core proteins (CD4, FGF23, Gal-9, PAR-1, REN, TNFRSF10A TNFRSF11A, and TNFRSF10B) are proposed. A one-unit change in the FI was additively associated with increased protein expression over 5 and 10 years (range: β-coefficients 0.52-1.59; p < 0.001). Increments in baseline FI consistently associated with a change in protein expression over time (5 years, β-range 0.05-1.35; 10 years, β-range 0.51-1.48; all p < 0.001). A one-unit increase in protein expression was also associated with an increased probability of being frail (FI ≥ 0.25) (β-range: 0.14-0.61). Mirroring the multisystem deterioration that typifies frailty, the proteins and their associated biological pathways reflect pathologies, including the renal system, skeletal homeostasis, and TRAIL-activated apoptotic signaling. The core proteins are compelling candidates for understanding the development and progression of frailty with advancing age, including the intrinsic musculoskeletal component. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Bone Turnover Markers: Basic Biology to Clinical Applications

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

Bone Turnover Marker Profiling and Fracture Risk in Older Women: Fracture Risk from Age 75 to 90

PURPOSE

A major challenge in osteoporosis is to identify individuals at high fracture risk. We investigated six bone turnover markers (BTMs) to determine association with specific fracture types; the time-frame for risk prediction and whether these are influenced by age at assessment.

METHODS

Population-based OPRA cohort (n = 1044) was assessed at ages 75, 80, 85 and fractures documented for up to 15 years. Six BTMs were analyzed at each time-point (N-terminal propeptide of type I collagen, PINP; total osteocalcin, OC; bone-specific alkaline phosphatase, BALP; C-terminal telopeptide of type I collagen, CTX; tartrate-resistant acid phosphatase 5b, TRAcP5b; urinary osteocalcin). Hazard ratios (HR) for any, major osteoporotic, vertebral and hip fractures were calculated as short (1, 2, 3 years) and long-term risk (5, 10, 15 years).

RESULTS

At 75 year, high CTX levels were associated with an increased risk of all fractures, including major osteoporotic fractures, across most time-frames (HRs ranging: 1.28 to 2.28). PINP was not consistently associated. Urinary osteocalcin was consistently associated with elevated short-term risk (HRs ranging: 1.83-2.72). Other BTMs were directionally in accordance, though not all statistically significant. BTMs were not predictive for hip fractures. Association of all BTMs attenuated over time; at 80 year none were associated with an increased fracture risk.

CONCLUSION

CTX, urinary OC and TRAcP5b are predictive for fracture in a 1 to 3 year, perspective, whereas in the long-term or above age 80 years, BTMs appear less valuable. Resorption markers, particularly CTX, were more consistently associated with fracture risk than formation markers in the very elderly.

The clinical utility of TRACP-5b to monitor anti-resorptive treatments of osteoporosis

TRACP-5b can be used to monitor the response of treatments in osteoporosis. We investigated the effect of feeding on levels of TRACP-5b and how these markers perform in a clinical setting. After feeding, there was no effect on levels TRACP-5b. It has similar diagnostic accuracy to CTX and PINP.

INTRODUCTION

Bone turnover markers (BTMs) can be used to monitor response to osteoporosis treatment. However, some are affected by food intake and are not suitable to measure in a clinical setting. An assay is available which is capable of detecting the active isoform 5b of tartrate resistance acid phosphatase (TRACP-5b) and it may have minimal biological variation. Our aims were to investigate the effect of feeding on levels of TRACP-5b and compare this to CTX and PINP and then to compare the diagnostic accuracy of TRACP-5b to CTX and PINP in patients with osteoporosis given commonly used treatments.

METHODS

Eighteen patients were recruited to investigate the effect of feeding on BTMs. Ninety-seven patients (74 females and 23 males) receiving 5 mg annual intra-venous zoledronate (mean age 70) and 97 patients receiving no treatment were recruited as group-matched controls. Sixteen patients receiving 60 mg subcutaneous denosumab every 6 months, (mean age 76) and 16 matched controls were recruited. Seventy-six patients were receiving oral bisphosphonates: 70 mg alendronate weekly, 35 mg risedronate and 150 mg monthly ibandronate (4%). Thirty of these patients had BMD measured at the total hip and lumbar spine. An estimate of compliance was not determined. Eighty patients receiving no treatment were recruited as group-matched controls. TRACP-5b (ELISA, Nittobo) and CTX and PINP were measured in serum in the non-fasting state between 0800 and 1700.

RESULTS

After feeding, there was no effect on levels TRACP-5b and significant reductions in CTX and PINP, 29% and 10%, respectively (p < 0.001). In the zoledronate and denosumab groups, there were no differences in the areas under the curves (AUCs) between TRACP-5b, PINP and CTX. In the oral bisphosphonates group, the AUCs between TRACP-5b and PINP and TRACP-5b and CTX were significantly different, p < 0.01 and p = 0.001, respectively. TRACP-5b was negatively correlated with BMD.

CONCLUSION

TRACP-5b is not affected by food intake, unlike CTX and PINP. All three BTMs correlate with change in BMD at the lumbar spine and total hip. TRACP-5b has similar diagnostic accuracy to CTX and PINP with commonly used treatments for osteoporosis with the exception of oral bisphosphonate therapy.

Serum levels of C-terminal telopeptide (CTX) are associated with muscle function in community-dwelling older adults

BACKGROUND

Markers of bone metabolism have been associated with muscle mass and function. Whether serum cross-linked C-terminal telopeptides of type I collagen (CTX) is also associated with these measures in older adults remains unknown.

METHODS

In community-dwelling older adults at high risk of falls and fractures, serum CTX (biochemical immunoassays) was used as the exposure, while appendicular lean mass (dual-energy x-ray absorptiometry) and muscle function (grip strength [hydraulic dynamometer], short physical performance battery [SPPB], gait speed, sit to stand, balance, Timed Up and Go [TUG]) were used as outcomes. Potential covariates including demographic, lifestyle and clinical factors were considered in statistical models. Areas under the ROC curves were calculated for significant outcomes.

RESULTS

299 older adults (median age: 79 years, IQR: 73, 84; 75.6% women) were included. In multivariable models, CTX was negatively associated with SPPB (β = 0.95, 95% CI: 0.92, 0.98) and balance (β = 0.92, 0.86, 0.99) scores, and positively associated with sit to stand (β = 1.02, 95% CI: 1.00, 1.05) and TUG (β = 1.03, 95% CI: 1.00, 1.05). Trend line for gait speed (β = 0.99, 95% CI: 0.98, 1.01) was in the hypothesized direction but did not reach significance. AUC curves showed low diagnostic power (<0.7) of CTX in identifying poor muscle function (SPPB: 0.63; sit to stand: 0.64; TUG: 0.61).

CONCLUSION

In older adults, higher CTX levels were associated with poorer lower-limb muscle function (but showed poor diagnostic power for these measures). These clinical data build on the biomedical link between bone and muscle.

The impact of acute fracture on interpretation of bone turnover marker measurements for patients starting anti-resorptive therapies

INTRODUCTION

Bone turnover markers (BTM) are used in evaluating patients' response to anti-resorptive agents (ARA). Fracture and its healing process, however, can influence the measurements, which might make their interpretation difficult in patients with a recent fracture. We aimed to evaluate the effect of oral ARA on changes in BTM levels in patients with a recent distal radius fracture (DRF).

METHODS

In 143 women who had a new DRF and then received oral ARA including selective estrogen receptor modulator (SERM, n = 101), and bisphosphonate (n = 42), we measured serum cross-linked C-telopeptides of type I collagen (CTXI) and osteocalcin, at baseline and six months, as well as lumbar and total hip bone mineral density (BMD) at baseline and one year after fracture. We determined the predictive value of BTM at six months in determining one-year responses in BMD.

RESULTS

Both BTM levels decreased significantly at six months, with the average decrease of 27 ± 63% for CTX-I and 11% ± 37% for osteocalcin. The percent changes of BTM at six months were independent predictors of the BMD change. Cutoff points of 50.0% CTX-I decrease and 23.5% for osteocalcin decrease had the highest sensitivities and specificities for detecting BMD responders for bisphosphonate users, but cutoffs could not be found for SERM users.

CONCLUSION

Although a fresh fracture can influence BTM, ARA therapy significantly reduced their levels and their percent change at six months could predict BMD improvement at one year. However, adjusted cutoff points can be necessary to increase sensitivity for detecting patients responsive to ARA treatment after a new DRF.

Pregnancy-Associated Plasma Protein (PAPP)-A2 in Physiology and Disease

The growth hormone (GH)/insulin-like growth factor (IGF) axis plays fundamental roles during development, maturation, and aging. Members of this axis, composed of various ligands, receptors, and binding proteins, are regulated in a tissue- and time-specific manner that requires precise control that is not completely understood. Some of the most recent advances in understanding the implications of this axis in human growth are derived from the identifications of new mutations in the gene encoding the pregnancy-associated plasma protein PAPP-A2 protease that liberates IGFs from their carrier proteins in a selective manner to allow binding to the IGF receptor 1. The identification of three nonrelated families with mutations in the PAPP-A2 gene has shed light on how this protease affects human physiology. This review summarizes our understanding of the implications of PAPP-A2 in growth physiology, obtained from studies in genetically modified animal models and the PAPP-A2 deficient patients known to date.

Recombinant IGF-1 Induces Sex-Specific Changes in Bone Composition and Remodeling in Adult Mice with Pappa2 Deficiency

Deficiency of pregnancy-associated plasma protein-A2 (PAPP-A2), an IGF-1 availability regulator, causes postnatal growth failure and dysregulation of bone size and density. The present study aimed to determine the effects of recombinant murine IGF-1 (rmIGF-1) on bone composition and remodeling in constitutive Pappa2 knock-out (ko/ko) mice. To address this challenge, X-ray diffraction (XRD), attenuated total reflection-fourier transform infra-red (ATR-FTIR) spectroscopy and gene expression analysis of members of the IGF-1 system and bone resorption/formation were performed. Pappa2^ko/ko mice (both sexes) had reduced body and bone length. Male Pappa2^ko/ko mice had specific alterations in bone composition (mineral-to-matrix ratio, carbonate substitution and mineral crystallinity), but not in bone remodeling. In contrast, decreases in collagen maturity and increases in Igfbp3, osteopontin (resorption) and osteocalcin (formation) characterized the bone of Pappa2^ko/ko females. A single rmIGF-1 administration (0.3 mg/kg) induced short-term changes in bone composition in Pappa2^ko/ko mice (both sexes). rmIGF-1 treatment in Pappa2^ko/ko females also increased collagen maturity, and Igfbp3, Igfbp5, Col1a1 and osteopontin expression. In summary, acute IGF-1 treatment modifies bone composition and local IGF-1 response to bone remodeling in mice with Pappa2 deficiency. These effects depend on sex and provide important insights into potential IGF-1 therapy for growth failure and bone loss and repair.

Algorithm for the Use of Biochemical Markers of Bone Turnover in the Diagnosis, Assessment and Follow-Up of Treatment for Osteoporosis

Introduction

Increased biochemical bone turnover markers (BTMs) measured in serum are associated with bone loss, increased fracture risk and poor treatment adherence, but their role in clinical practice is presently unclear. The aim of this consensus group report is to provide guidance to clinicians on how to use BTMs in patient evaluation in postmenopausal osteoporosis, in fracture risk prediction and in the monitoring of treatment efficacy and adherence to osteoporosis medication.

Methods

A working group with clinical scientists and osteoporosis specialists was invited by the Scientific Advisory Board of European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO).

Results

Serum bone formation marker PINP and resorption marker βCTX-I are the preferred markers for evaluating bone turnover in the clinical setting due to their specificity to bone, performance in clinical studies, wide use and relatively low analytical variability. BTMs cannot be used to diagnose osteoporosis because of low sensitivity and specificity, but can be of value in patient evaluation where high values may indicate the need to investigate some causes of secondary osteoporosis. Assessing serum levels of βCTX-I and PINP can improve fracture prediction slightly, with a gradient of risk of about 1.2 per SD increase in the bone marker in addition to clinical risk factors and bone mineral density. For an individual patient, BTMs are not useful in projecting bone loss or treatment efficacy, but it is recommended that serum PINP and βCTX-I be used to monitor adherence to oral bisphosphonate treatment. Suppression of the BTMs greater than the least significant change or to levels in the lower half of the reference interval in young and healthy premenopausal women is closely related to treatment adherence.

Conclusion

In conclusion, the currently available evidence indicates that the principal clinical utility of BTMs is for monitoring oral bisphosphonate therapy.

Metformin decreases bone turnover markers in polycystic ovary syndrome: a post hoc study

OBJECTIVE

To study the effects of metformin treatment on bone turnover in women with polycystic ovary syndrome (PCOS), as measured by serum concentrations of bone turnover markers.

DESIGN

Post hoc study of a previously conducted prospective multicenter, placebo-controlled, randomized study.

SETTING

University clinic.

PATIENT(S)

The study cohort consisted of 74 non-obese women (body mass index < 27 kg/m²) and 44 obese women (body mass index ≥ 27 kg/m²) diagnosed with PCOS, with a mean age of 27.6 ± 4.0 (SD) years.

INTERVENTION(S)

Randomization to receive metformin or placebo for 3 months.

MAIN OUTCOME MEASURE(S)

Serum levels of bone formation marker procollagen type I amino-terminal propeptide (PINP) and bone resorption marker carboxy-terminal cross-linking telopeptide of type I collagen (CTX) at baseline and after metformin/placebo treatment.

RESULT(S)

Serum levels of PINP and CTX were similar between the metformin and placebo groups at baseline in the whole study population. Obese women, when compared with non-obese, had lower baseline levels of PINP and CTX. Levels of PINP and CTX were significantly reduced in the whole study population, as well as in both non-obese and obese women after 3 months of metformin treatment, whereas no significant changes were observed in the placebo group.

CONCLUSION(S)

Metformin treatment, when compared with placebo, was associated with reduced bone turnover, as suggested by reductions in markers of bone formation and resorption, leading to slower bone remodeling in premenopausal women with PCOS.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00994812.

Relationship between bone turnover markers and the heel stiffness index measured by quantitative ultrasound in post-menopausal Japanese women

Background: Osteoporosis in women is a serious health problem. The relationships between biochemical markers of bone turnover and bone mineral density (BMD) in women have been reported, but no study has examined relationships between tartrate-resistant acid phosphatase-5b (TRACP-5b) or bone-specific alkaline phosphatase (BAP) and bone mass measured by quantitative ultrasound (QUS) in Japanese post-menopausal women. Aim: To investigate the serum TRACP-5b and BAP levels and to determine their associations with the heel stiffness index measured by QUS in post-menopausal women. Subjects and methods: The subjects were 510 post-menopausal women who were invited to participate in periodic health examinations in 2011-2013 (the Unzen Study). The heel stiffness index (bone mass) was measured by QUS. Serum samples were collected and TRACP-5b and BAP levels were measured. Results: Multiple regression analysis showed that a higher log (TRACP-5b) was correlated with a lower stiffness index (p = 0.014) and log (BAP) was not correlated with stiffness index after adjusting for covariates (p = 0.136). Conclusion: Higher rates of bone resorption are associated with a lower stiffness index in Japanese post-menopausal women. These results may indicate that high bone resorption affects bone mass more than bone formation, resulting in a low bone mass.

Bone turnover markers in women participating in a dose-finding trial of a contraceptive vaginal ring releasing Nestorone and estradiol

OBJECTIVE

To evaluate changes in the bone turnover markers CTx and P1NP during 6 months' use of novel continuous contraceptive vaginal rings delivering Nestorone (NES) 200 mcg/day and three doses of estradiol (E2) (10, 20, and 40 mcg/day).

STUDY DESIGN

This randomized trial enrolled 189 women who used two consecutive vaginal rings over 180 days. Frequent blood sampling permitted analysis of NES, E2, CTx and P1NP concentrations. The bone-turnover marker analyses included only women with complete sampling and excluded women with characteristics that might interfere with accurate measurement of bone markers such as afternoon sampling, poor ring compliance or recent pregnancy. We evaluated the change from baseline to 6 months in CTx and P1NP, stratified by ring dose and by average circulating E2 concentrations.

RESULTS

One hundred fifty-one women completed the study, and 82 women had complete data available for the bone marker analyses; the three dosage groups were balanced with regard to baseline characteristics. E2 concentrations remained low throughout treatment, regardless of which dose ring the participant used. Individual CTx changes from baseline averaged 27±56% (p<.01). Similarly, individual P1NP changes averaged 11±33% (p=.04). These increases were within the premenopausal reference ranges, and unrelated to treatment dose or to circulating E2 concentrations.

CONCLUSIONS

The low E2 dose of these rings was associated with low E2 concentrations and modest increases in serum bone turnover makers. Because we have only 6-month bone turnover markers and no direct evidence of bone loss or bone density change, these results must be interpreted with caution.

IMPLICATIONS

Nestorone, a 19-norprogesterone derivative, leads to complete ovarian suppression, which should yield excellent contraceptive effectiveness. To prevent potential adverse effects on bone, the NES contraceptive ring should be combined with higher doses of E2 than were assessed in this study.

Bone turnover: Biology and assessment tools

Bone turnover includes two processes: resorption (removal of old bone) and formation (laying down of new bone). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that the International Osteoporosis Foundation and the International Federation of Clinical Chemistry recommend for clinical use. Bone turnover markers (BTM) are subject to sources of variability, including feeding (lower resorption) and recent fracture (increased levels of all markers). Controllable patient-related factors should be adapted as much as possible (eg blood collection after an overnight fast) to minimize pre-analytical variability. Uncontrollable factors should be considered in the interpretation of the BTM measurements. BTM do not improve prediction of bone loss or fracture within an individual. In osteoporotic patients, BTM may help to assess the response to anabolic and antiresorptive therapies, to assess compliance to the treatment, or to indicate possible secondary causes of osteoporosis. BTM reflect changes in bone metabolism induced by anti-osteoporotic treatment. Anti-resorptive drugs induce a rapid dose-dependent decrease in bone resorption, whereas bone formation stimulating medications increase the levels of bone formations markers. BTM may be used for monitoring anti-osteoporosis therapy. The expected effect during the anti-resorptive therapy is to decrease the PINP by at least 10 ng/mL and to attain the target level of less than 35 ng/mL. The expected effect during the bone formation-stimulating therapy is to increase the PINP by at least 10 ng/mL and to attain the target level of more than 69 ng/mL.

The Changes of CTX, DPD, Osteocalcin, and Bone Mineral Density During the Postmenopausal Period

Objective

To investigate appropriate treatment time and useful bone turnover markers (BTMs) for monitoring bone turnover during the postmenopausal period, we analyzed changes of two bone resorption markers; serum carboxyterminal telopeptide of collagen I (s-CTX), urine deoxypyridinoline (u-DPD), one bone formation marker; serum osteocalcin (s-OC), and bone mineral density (BMD) in Korean postmenopausal women.

Methods

Seventy-eight menopausal women were divided into three groups according to postmenopausal period: group I (0–5 years), group II (6–10 years), group III (≥10 years). All groups were subdivided into an osteoporosis group (T-score≤-2.5) and a non-osteoporosis group (T-score>-2.5). BTMs such as s-CTX, u-DPD, s-OC, and BMD (g/cm²) were measured by dual-energy X-ray absorptiometry (DXA) in all patients. Analysis of variables among groups based on the postmenopausal period was performed using ANOVA.

Results

There was significant negative correlation between BMD and postmenopausal period. The levels of all BTMs including s-CTX, u-DPD, and s-OC were highest in group II and the increased levels of all BTMs subsequently declined in group III. The levels of BTMs were higher in the osteoporosis groups than in the non-osteoporosis groups in all subjects. It was statistically significant that the level of s-CTX in group I was higher in the osteoporosis group than in the non-osteoporosis group.

Conclusion

This study showed that bone resorption and bone formation were the highest 5–10 years after menopause, and s-CTX is more useful than u-DPD among the bone resorption markers. It’s important to measure serially both BMD and BTM within 10 years after menopause for accurate diagnosis and management for postmenopausal osteoporosis.

Effect of isolated vitamin D supplementation on bone turnover markers in younger postmenopausal women: a randomized, double-blind, placebo-controlled trial

Vitamin D (VD) plays an important role in bone mineralization. The present study investigates the effect of VD supplementation alone on bone turnover markers in younger postmenopausal women. It has been shown that VD supplementation in postmenopausal women with hypovitaminosis D is associated with a reduction in bone turnover markers.

PURPOSE

The purpose of this study is to evaluate the effect of VD supplementation alone on bone turnover markers in younger postmenopausal women.

METHODS

In this double-blind, placebo-controlled trial, 160 women were randomized into the VD group (supplementation with 1000 IU of vitamin D3/day, orally; n = 80) or placebo group (n = 80). Women aged 50-65 years with amenorrhea ≥ 12 months and normal bone mineral density were included. The intervention lasted 9 months, and the participants were assessed at the beginning and end of treatment. Serum levels of total calcium, parathormone (PTH), alkaline phosphatase (AP), and 24-h urine calcium were determined. Serum C-terminal telopeptide of type I collagen (s-CTX) and procollagen type 1 N-terminal propeptide (P1NP) were measured by immunoassay as markers of bone resorption and formation, respectively. Plasma 25-hydroxyvitamin-D [25(OH)D] concentrations were measured by HPLC. Intention-to-treat analysis was performed using ANOVA, Student's t test, Tukey's test, and gamma distribution.

RESULTS

Over the period of 9 months, 25(OH)D concentrations increased from 15.0 ± 7.5 to 27.5 ± 10.4 ng/mL (+ 45.4%) in the VD group and decreased from 16.9 ± 6.7 to 13.8 ± 6.0 ng/mL (- 18.5%) in the placebo group (p < 0.001). There was a decrease (- 21.3%) of PTH levels in the VD group with a significant difference between groups at the end of the study (p < 0.001). No significant differences were observed in the other laboratory parameters (total calcium, AP, and calciuria) in either group (p > 0.05). A comparison of bone turnover markers showed a significant reduction in of s-CTX (- 24.2%, p < .0001) and P1NP (- 13.4%, p = 0.003) levels in the VD group. No significant variations in bone turnover markers were observed in the placebo group (s-CTX, - 6.9%, p = 0.092 and P1NP, - 0.6%, p = 0.918).

CONCLUSION

In younger postmenopausal women with VD deficiency, isolated supplementation with 1000 IU of vitamin D3 for 9 months is associated with a reduction in bone turnover markers. However, any between-group differences was not observed in bone turnover markers.

Osteoporosis and its perspective in Pakistan: A review of evidence and issues for addressing fragility fractures

Despite major advances in osteoporosis diagnosis and treatment, low rates of investigating and treating osteoporosis in patients with fragility fracture are reported in Pakistan. Cost of therapies, time and cost of resources for diagnosis, concerns about medications and lack of clarity regarding the onus of responsibility to undertake this care, are some of the barriers to osteoporosis identification and treatment. Data from our part of the world on osteoporosis as well as on fragility fractures is sparse. This review addresses the current screening and diagnostic strategies for osteoporosis and reviews the existing literature to highlight the issues prevalent in our society on this major public health problem.

Relationship between bone turnover markers and the heel stiffness index measured by quantitative ultrasound in middle-aged and elderly Japanese men

The aim of the present study was to investigate the age-related patterns and the relationships between serum levels of tartrate-resistant acid phosphatase-5b (TRACP-5b) or bone-specific alkaline phosphatase (BAP), and the heel stiffness index measured by quantitative ultrasound (QUS) in 429 Japanese men, with special emphasis on 2 age groups (40-59 years and 60 years or over). The heel stiffness index (bone mass) was measured by QUS. Serum samples were collected, and TRACP-5b and BAP levels were measured. The stiffness index was significantly decreased with age. Log (TRACP-5b) was significantly increased with age, but Log (BAP) was stable. Generalized linear models showed that higher levels of Log (TRACP-5b) and Log (BAP) were correlated with a lower stiffness index after adjusting for covariates in men aged 60 years or over, but not in men aged 40 to 59 years. In conclusion, higher rates of bone turnover markers were associated with a lower stiffness index only in elderly men. These results may indicate a different mechanism of low bone mass among different age groups of men.

DIAGNOSIS OF ENDOCRINE DISEASE: Bone turnover markers: are they clinically useful?

Bone turnover markers (BTMs) are useful in clinical practice as they are inexpensive, and they have proven useful for treatment monitoring and identification of poor adherence. BTMs cannot be used in individual patients for identifying accelerated bone loss or an increase in fracture risk or in deciding on the optimal therapy. They are useful for monitoring both anti-resorptive and anabolic treatment. Response can be defined as a result that exceeds an absolute target, or by a change greater than the least significant change; if such a response is not present, then poor compliance or secondary osteoporosis are likely causes. A baseline BTM measurement is not always made; in that case, a value of BTM on anti-resorptive treatment that is low or low normal or above the reference interval for anabolic therapy may be taken to indicate a satisfactory response. We provide an approach to using these bone turnover markers in clinical practice by describing algorithms for anti-resorptive and anabolic therapy and describing the changes we observe in the clinical practice setting.

Use of bone turnover markers in postmenopausal osteoporosis

Bone turnover comprises two processes: the removal of old bone (resorption) and the laying down of new bone (formation). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that are recommended for clinical use. Bone turnover markers can be measured on several occasions in one individual with good precision. However, these markers are subject to several sources of variability, including feeding (resorption decreases) and recent fracture (all markers increase for several months). Bone turnover markers are not used for diagnosis of osteoporosis and do not improve prediction of bone loss or fracture within an individual. In untreated women, very high bone turnover marker concentrations suggest secondary causes of high bone turnover (eg, bone metastases or multiple myeloma). In people with osteoporosis, bone turnover markers might be useful to assess the response to anabolic and antiresorptive therapies, to assess compliance to therapy, or to indicate possible secondary osteoporosis. Much remains to be learnt about how bone turnover markers can be used to monitor the effect of stopping bisphosphonate therapy (eg, to identify a threshold above which restarting therapy should be considered). More studies are needed to investigate the use of bone turnover markers for assessment of the bone safety of new medications.

Metabolomics and Its Application in the Development of Discovering Biomarkers for Osteoporosis Research

Osteoporosis is a progressive skeletal disorder characterized by low bone mass and increased risk of fracture in later life. The incidence and costs associated with treating osteoporosis cause heavy socio-economic burden. Currently, the diagnosis of osteoporosis mainly depends on bone mineral density and bone turnover markers. However, these indexes are not sensitive and accurate enough to reflect the osteoporosis progression. Metabolomics offers the potential for a holistic approach for clinical diagnoses and treatment, as well as understanding of the pathological mechanism of osteoporosis. In this review, we firstly describe the study subjects of osteoporosis and bio-sample preparation procedures for different analytic purposes, followed by illustrating the biomarkers with potentially predictive, diagnosis and pharmaceutical values when applied in osteoporosis research. Then, we summarize the published metabolic pathways related to osteoporosis. Furthermore, we discuss the importance of chronological data and combination of multi-omics in fully understanding osteoporosis. The application of metabolomics in osteoporosis could provide researchers the opportunity to gain new insight into the metabolic profiling and pathophysiological mechanisms. However, there is still much to be done to validate the potential biomarkers responsible for the progression of osteoporosis and there are still many details needed to be further elucidated.

Association of bone turnover markers with volumetric bone loss, periosteal apposition, and fracture risk in older men and women: the AGES-Reykjavik longitudinal study

Association between serum bone formation and resorption markers and cortical and trabecular bone loss and the concurrent periosteal apposition in a population-based cohort of 1069 older adults was assessed. BTM levels moderately reflect the cellular events at the endosteal and periosteal surfaces but are not associated with fracture risk.

INTRODUCTION

We assessed whether circulating bone formation and resorption markers (BTM) were individual predictors for trabecular and cortical bone loss, periosteal expansion, and fracture risk in older adults aged 66 to 93 years from the AGES-Reykjavik study.

METHODS

The sample for the quantitative computed tomography (QCT)-derived cortical and trabecular BMD and periosteal expansion analysis consisted of 1069 participants (474 men and 595 women) who had complete baseline (2002 to 2006) and follow-up (2007 to 2011) hip QCT scans and serum baseline BTM. During the median follow-up of 11.7 years (range 5.4-12.5), 54 (11.4 %) men and 182 (30.6 %) women sustained at least one fracture of any type.

RESULTS

Increase in BTM levels was associated with faster cortical and trabecular bone loss at the femoral neck and proximal femur in men and women. Higher BTM levels were positively related with periosteal expansion rate at the femoral neck in men. Markers were not associated with fracture risk.

CONCLUSION

This data corroborates the notion from few previous studies that both envelopes are metabolically active and that BTM levels may moderately reflect the cellular events at the endosteal and periosteal surfaces. However, our results do not support the routine use of BTM to assess fracture risk in older men and women. In light of these findings, further studies are justified to examine whether systemic markers of bone turnover might prove useful in monitoring skeletal remodeling events and the effects of current osteoporosis drugs at the periosteum.

Teriparatide and denosumab combination therapy and skeletal metabolism

Several therapies are available for osteoporis. Understanding the bone turnover changes and their mutual realtionship gives an overall view and might lead to a target therapy INTRODUCTION: The aim of this study is to compare the changes in bone turnover markers in patients treated with either denosumab alone, teriparatide (TPTD) alone, or in a third therapeutic scheme, when TPTD was added to patients previously treated with denosumab.

METHODS

Fifty-nine women over 65 years old with severe postmenopausal osteoporosis (evidence of at least two moderate-severe vertebral fractures) were enrolled in the study. Serum samples were collected every 3 months. They were assayed for intact N-propeptide of type I collagen (P1NP), C-terminal telopeptide of type I collagen (CTX), intact parathyroid hormone (PTH), 25 hydroxy-vitamin D (25 OHD), Sclerostin (SOST), and Dickkopf-related protein 1 (DKK1). Bone mass density was assessed by dual-energy X-ray absorptiometry at the lumbar spine and at the total hip.

RESULTS

In the groups treated only with TPTD or with denosumab, bone turnover markers increased and decreased, respectively. In TPTD group, a later significant increase in DKK1 was observed, while in denosumab group, a progressive increase in SOST was associated with a progressive significant decrease in DKK1. In the group treated first with denosumab and in which TPTD was added 3 months later, both CTX and P1NP increased 3 months after the beginning of TPTD. The strong effect of denosumab on bone turnover seems to be reversed by TPTD treatment.

CONCLUSIONS

In this study, we showed that TPTD is able to express its biological activity even when bone turnover is fully suppressed by denosumab treatment. The combination therapy is associated with significant increases in both DKK1 and SOST.

The role of biochemical of bone turnover markers in osteoporosis and metabolic bone disease: a consensus paper of the Belgian Bone Club

The exact role of biochemical markers of bone turnover in the management of metabolic bone diseases remains a topic of controversy. In this consensus paper, the Belgian Bone Club aimed to provide a state of the art on the use of these biomarkers in different clinical or physiological situations like in postmenopausal women, osteoporosis in men, in elderly patients, in patients suffering from bone metastasis, in patients with chronic renal failure, in pregnant or lactating women, in intensive care patients, and in diabetics. We also gave our considerations on the analytical issues linked to the use of these biomarkers, on potential new emerging biomarkers, and on the use of bone turnover biomarkers in the follow-up of patients treated with new drugs for osteoporosis.

Tartrate-Resistant Acid Phosphatase 5b in Young Patients With Sickle Cell Disease and Trait Siblings: Relation to Vasculopathy and Bone Mineral Density

Bone involvement is a frequent cause of acute morbidity in sickle cell disease (SCD). Tartrate-resistant acid phosphatase 5b (TRACP 5b), a bone resorption marker, is produced specifically by activated osteoclasts. We assessed bone mineral density (BMD) in 30 young patients with SCD and 17 asymptomatic patients with sickle cell trait (SCT) compared with 32 healthy controls and determined TRACP 5b levels in relation to vascular complications. Serum ferritin, alkaline phosphatase (ALP), and TRACP 5b were measured. Echocardiography was performed with assessment of BMD using dual energy X-ray absorptiometry (DXA). The BMD was decreased in patients with SCD compared with SCT and controls (P = .005), with no significant difference between the latter 2 groups. Patients with SCD had higher incidence of bone complications than SCT group and controls (P = .03). The SCD group with abnormal DXA scan had higher ferritin and ALP than normal BMD. Serum TRACP 5b was significantly higher in patients with SCD than SCT and controls (P = .003). The TRACP 5b levels were associated with severe vaso-occlusive crisis (P = .022). Patients treated with hydroxyurea and those on chelation therapy had lower TRACP 5b levels than untreated patients. The TRACP 5b level was positively correlated with lactate dehydrogenase, while there was no relation with ferritin, ALP, or BMD. We suggest that bone complications frequently occur in SCD as reflected by low BMD and high ALP and TRACP 5b. Hemolysis and iron overload may be involved in the occurrence of these complications. The lack of correlation between abnormal DXA scan and high TRACP 5b suggests that bone disease in SCD is multifactorial.

[Clinical heterogeneity of atypical fractures during prolonged use of bisphosphonates--risk factors and bone turnover markers]

We describe four cases of atypical femoral fractures treated at the Department of Endocrinology, Hospital de Clínicas, Federal University of Paraná (SEMPR) which, although characteristic of this type of fracture, presented clinical peculiarities that should be considered and serve as a warning in these patients, such as: late diagnosis with maintenance of bisphosphonates; absence of co-morbidities with excellent result; failure of fracture healing; use of anabolic medication after the fracture and the use of bone turnover markers at the follow up.

Polymorphisms in the inflammatory genes CIITA, CLEC16A and IFNG influence BMD, bone loss and fracture in elderly women

Osteoclast activity and the fine balance between bone formation and resorption is affected by inflammatory factors such as cytokines and T lymphocyte activity, mediated by major histocompatibility complex (MHC) molecules, in turn regulated by the MHC class II transactivator (MHC2TA). We investigated the effect of functional polymorphisms in the MHC2TA gene (CIITA), and two additional genes; C-type lectin domain 16A (CLEC16A), in linkage disequilibrium with CIITA and Interferon-γ (IFNG), an inducer of CIITA; on bone density, bone resorption markers, bone loss and fracture risk in 75 year-old women followed for up to 10 years (OPRA n = 1003) and in young adult women (PEAK-25 n = 999). CIITA was associated with BMD at age 75 (lumbar spine p = 0.011; femoral neck (FN) p = 0.049) and age 80 (total body p = 0.015; total hip p = 0.042; FN p = 0.028). Carriers of the CIITA rs3087456(G) allele had 1.8–3.4% higher BMD and displayed increased rate of bone loss between age 75 and 80 (FN p = 0.013; total hip p = 0.030; total body p = 3.8E⁻⁵). Despite increasing bone loss, the rs3087456(G) allele was protective against incident fracture overall (p = 0.002), osteoporotic fracture and hip fracture. Carriers of CLEC16A and IFNG variant alleles had lower BMD (p<0.05) and ultrasound parameters and a lower risk of incident fracture (CLEC16A, p = 0.011). In 25-year old women, none of the genes were associated with BMD. In conclusion, variation in inflammatory genes CIITA, CLEC-16A and INFG appear to contribute to bone phenotypes in elderly women and suggest a role for low-grade inflammation and MHC class II expression for osteoporosis pathogenesis.

Is there a place for bone turnover markers in the assessment of osteoporosis and its treatment?

As populations age, the number of osteoporotic fractures will increase. Bone mineral density (BMD) measurement remains the major way to diagnose osteoporosis and to indicate therapy. The FRAX tool, based on clinical risk factors, estimates the 10-year risk of hip and major osteoporotic fractures. The association of BMD and FRAX measurements has improved the identification of patients who are most at risk. However, some patients can still be overlooked and denied therapy. It is sound that adding the measure of bone turnover markers to the former risk factors and their follow-up during therapy could best address the efficacy of treatment of osteoporosis. Whether this behavior is cost-effective remains to be settled.

Effect of precision on longitudinal follow-up of bone mineral density measurements in elderly women and men

Precision error of dual-energy X-ray absorptiometry exceeds the expected annual rate of bone loss in the elderly. The capacity to detect changes in areal bone mineral density (aBMD; g/cm(2)) over a 5-yr period was assessed. Six hundred ninety-one women, 75.2 (0.1)yr, from the Malmö OPRA-study, were measured using Lunar DPX-L (GE Lunar, Madison, WI), and 211 men, 74.7 (3.2)yr, from the Malmö Mr Os-study, were measured using Lunar Prodigy (GE Lunar) with follow-up 5 yr later. Precision error was determined with 30 degrees of freedom. Least significant change (LSC, i.e., 2.77 × precision error) was calculated. Women's precision errors (g/cm(2)) for DPX-L were 0.028 (total hip [TH]) and 0.016 (lumbar spine [LS]), and for Prodigy, they were 0.009 (TH) and 0.039 (LS). In men, corresponding results for Prodigy were 0.014 and 0.031. In women, 41% and in men, 39% had aBMD changes exceeding the LSC at TH. Follow-up intervals (i.e., LSC/median rate of aBMD change) for both women and men were 8 yr (TH) and 13 yr (LS). Based on Prodigy precision data, follow-up intervals for women were 3 and 32 yr at TH and LS. In summary, several years were needed to detect change. Only when a high rate of bone loss is suspected, a short follow-up time is possible, in elderly persons.

Polymorphisms in the macrophage migration inhibitory factor gene and bone loss in postmenopausal women

Osteoporosis is a severe condition in postmenopausal women and a common cause of fracture. Osteoporosis is a complex disease with a strong genetic impact, but susceptibility is determined by many genes with modest effects and environmental factors. Only a handful of genes consistently associated with osteoporosis have been identified so far. Inflammation affects bone metabolism by interfering with the interplay between bone resorption and formation, and many inflammatory mediators are involved in natural bone remodeling. The cytokine macrophage migration inhibitory factor (MIF) has been shown to affect bone density in rodents, and polymorphisms in the human MIF promoter are associated with inflammatory disorders such as rheumatoid arthritis. We investigated the association of polymorphisms in the MIF gene with bone mineral density (BMD) and bone loss in 1002 elderly women using MIF promoter polymorphisms MIF-CATT(5-8) and rs755622(G/C) located -794 and -173 bp upstream of the transcriptional start site. Bone loss was estimated both by the change in BMD over 5 years and by the levels of bone resorption markers in serum measured at four occasions during a 5-year period. The MIF-CATT(7)/rs755622(C) haplotype was associated with increased rate of bone loss during 5 years at the femoral neck (p<0.05) and total hip (p<0.05). In addition, the MIF-CATT(7)/rs755622(C) haplotype carriers had higher levels of the bone turnover marker serum C-terminal cross-linking telopeptide of type I collagen (S-CTX-I, p<0.01) during the 5 year follow-up period. There was no association between MIF-CATT(7)/rs755622(C) and baseline BMD at femoral neck, total hip or lumbar spine. We conclude that MIF promoter polymorphisms have modest effects on bone remodeling and are associated with the rate of bone loss in elderly women.

Osteocalcin gene polymorphisms influence concentration of serum osteocalcin and enhance fracture identification

Osteoporosis is a major health problem affecting more than 75 million people throughout Europe, the United States, and Japan. Epidemiologic studies have determined that both genetic and environmental factors contribute to the pathogenesis of osteoporosis. We have investigated the association between polymorphisms at the osteocalcin locus and variables linked to bone health. Osteocalcin provides a link between bone and energy metabolism, hence its potential importance as an osteoporosis candidate gene. In this study, we included a total of 996 women (all aged 75 years) from the Osteoporosis Prospective Risk Assessment (OPRA) cohort. We sequenced the osteocalcin gene along with flanking regions to search for novel coding polymorphisms. We also analyzed four polymorphisms selected from within and flanking regions of the osteocalcin gene to study their association with serum total osteocalcin levels (S-TotalOC), total-body (TB) bone mineral density (BMD), fracture, TB fat mass, and body mass index (BMI). The promoter polymorphism rs1800247 was significantly associated with S-TotalOC (p = .012) after controlling for BMI and TB BMD. The polymorphism rs1543297 was significantly associated with prospectively occurring fractures (p = .008). In a model taking into account rs1543297 and rs1800247, along with TB BMD, BMI, smoking, and S-TotalOC, the polymorphisms together were able to identify an additional 6% of women who sustained a fracture (p = .02). We found no association between the polymorphisms and TB BMD, BMI, or TB fat mass. In conclusion, polymorphisms in and around the osteocalcin locus are significantly associated with S-TotalOC and fracture. Genotyping at the osteocalcin locus could add valuable information in the identification of women at risk of osteoporosis.

Markers of Bone Formation and Resorption Identify Subgroups of Patients with Clinical Knee Osteoarthritis Who Have Reduced Rates of Cartilage Loss

Objective.

To determine whether serum markers of bone formation and resorption, used individually or in combination, can be used to identify subgroups who lose cartilage volume at different rates over 2 years within a knee osteoarthritis (OA) population.

Methods.

Changes in cartilage volume over 2 years were measured in 117 subjects with knee OA using magnetic resonance imaging. We examined relationships between change in cartilage volume and baseline serum markers of bone formation [intact N-terminal propeptide of type I procollagen (PINP) and osteocalcin] and resorption [N-telopeptide of type I collagen (NTX-I), C-telopeptide of type I collagen (CTX-I), and C-telopeptide of type I collagen (ICTP).

Results.

The baseline markers of bone formation, PINP and osteocalcin (p = 0.02, p = 0.01, respectively), and the baseline markers of bone resorption, CTX-I and NTX-I (p = 0.02 for both), were significantly associated with reduced cartilage loss. There were no significant associations between baseline ratios of bone formation to resorption markers and cartilage loss. However, when subjects were divided into subgroups with high or low bone formation markers (based on levels of marker ≥ mean or < mean for the population, respectively), in the subgroup with high PINP there was a significant association between increasing bone resorption markers CTX-I and NTX-I and reduced cartilage loss (p = 0.02, p = 0.001, respectively). Similarly, in the subgroup with high osteocalcin, there was a significant association between increasing CTX-I and NTX-I and reduced cartilage loss (p = 0.02, p = 0.003, respectively). In contrast, in subgroups with low bone formation markers, no significant associations were obtained between markers of bone resorption and cartilage loss.

Conclusion.

Overall, the results suggest that higher bone remodeling (i.e., higher serum levels of bone formation and resorption) is associated with reduced cartilage loss. Considering markers of bone formation and resorption together, it is possible to identify subgroups within the OA population who have reduced rates of cartilage loss.

Bone turnover assessment: a good surrogate marker?

To asses fracture risk, bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is the most commonly used tool. The search for clinical risk factors is also advised and can provide a 10-year fracture probability (FRAX model). Another important determinant of bone strength is bone remodeling. High bone remodeling rates have been associated with a higher fracture risk and bone turnover markers (BTM) may offer dynamic information about skeletal status independent of BMD. The efficacy of antiresorptive agents in fracture prevention goes beyond what can be predicted by BMD especially in the beginning of the treatment. Inhibition of bone remodeling itself is certainly an important mechanism by which antiresorptive agents can rapidly reduce fracture risk. Thus, it seems quite logical to use BTM in patients with bone disease. It can also become a valuable surrogate marker in fracture prediction. However, BTM's pre-analytical and analytical variability should always be considered.

Bone turnover markers and prediction of fracture: a prospective follow-up study of 1040 elderly women for a mean of 9 years

Osteoporosis is characterized by compromised bone mass and strength, predisposing to an increased risk of fracture. Increased bone metabolism has been suggested to be a risk factor for fracture. The aim of this study was to evaluate whether baseline bone turnover markers are associated with long-term incidence of fracture in a population-based sample of 1040 women who were 75 years old (Malmö OPRA study). Seven bone markers (S-TRACP5b, S-CTX-I, S-OC[1-49], S-TotalOC, S-cOC, S-boneALP, and urinary osteocalcin) were measured at baseline and 1-year follow-up visit. During the mean follow-up of 9.0 years (range 7.4-10.9), 363 women sustained at least one fracture of any type, including 116 hip fractures and 103 clinical vertebral fractures. High S-TRACP5b and S-CTX-I levels were associated with increased risk of any fracture with hazard ratios [HRs (95% confidence interval)] of 1.16 (1.04-1.29) and 1.13 (1.01-1.27) per SD increase, respectively. They also were associated with increased risk of clinical vertebral fracture with HRs of 1.22 (1.01-1.48) and 1.32 (1.05-1.67), respectively. Markers were not associated with risk for hip fracture. Results were similar when we used resorption markers, including urinary osteocalcin, measured at the 1-year visit or an average of the two measurements. The HRs were highest for any fracture in the beginning of the follow-up period, 2.5 years from baseline. For vertebral fractures, the association was more pronounced and lasted for a longer period of time, at least for 5 years. In conclusion, elevated levels of S-TRACP5b, S-CTX-I, and urinary osteocalcin are associated with increased fracture risk for up to a decade in elderly women.

Bone markers in osteoporosis

Current biological markers of bone turnover have proven useful in improving fracture risk assessment and monitoring treatment efficacy in postmenopausal osteoporosis. Recent developments in the field of bone markers include 1) identification of new biochemical markers providing additional information on the complex pathways leading to bone fragility; 2) application of novel technologies such as proteomics for the discovery of novel markers; 3) automation and multiplexing for improving analytical performance and convenience; and 4) refinement of the clinical interpretation of markers. Currently, however, for the management of individual patients, their most established application is to monitor treatment efficacy and possibly to improve fracture risk assessment. The role of bone markers for improving adherence to therapy will need to be investigated in further studies. This brief review discusses these novel technological developments and the recent clinical data on the use of established and new markers in postmenopausal osteoporosis.

Bone turnover markers are correlated with quantitative ultrasound of the calcaneus: 5-year longitudinal data

SUMMARY

Associations between bone turnover markers and calcaneal ultrasound (quantitative ultrasound, QUS) were studied in a population-based sample of 810 elderly women. Baseline bone turnover markers correlated with baseline QUS as well as with 5-year prospective changes in QUS.

INTRODUCTION

Bone turnover markers are associated with areal bone mineral density, but the knowledge on the association with QUS is limited.

METHODS

Eight hundred ten women, all 75 years old, were investigated at baseline. Five hundred six completed a 5-year follow-up. Bone turnover markers and calcaneal QUS [speed of sound (SoS), broadband ultrasound attenuation (BUA), stiffness] were investigated at baseline. QUS was investigated at follow-up.

RESULTS

All bone turnover markers were correlated with baseline QUS [standardized regression (Beta(std)) values from -0.07, p < 0.05 to -0.23, p < 0.001], with the exception of bone-specific alkaline phosphatase (S-Bone ALP) which was not correlated with BUA and stiffness index. When the correlations between baseline bone turnover markers and 5-year changes in QUS were analyzed, three serum osteocalcins were correlated with changes of SoS and stiffness index (Beta(std) = -0.11, p < 0.05 to -0.17, p < 0.001). Also S-CTX-I correlated with changes of SoS and stiffness index (Beta(std) = -0.10 and -0.09, respectively, p < 0.05). S-TRACP5b, urinary deoxypyridinoline/crea, and U-MidOC/crea correlated with changes of SoS (Beta(std) = -0.10 and p < 0.05 for all). S-Bone ALP did not correlate with change of QUS. None of the bone turnover markers correlated with changes of BUA.

CONCLUSIONS

Bone turnover markers correlate with concomitantly assessed QUS as well as with longitudinal change in QUS.

The bone marker plot: an innovative method to assess bone turnover in women

BACKGROUND

Biochemical markers of bone turnover reflect the resorptive and reconstructive effects that act on the skeleton. Although elevated markers are commonly interpreted as a sign of an increased turnover rate, the balance between bone resorption and formation is mostly neglected. We introduce a graphic report combining both complementary processes.

MATERIALS AND METHODS

Bone turnover markers were measured in 599 women (aged 25-74 years). To set up reference ranges, 269 from 599 women were selected because of having T-scores > -1 and inconspicuous basic laboratory data. Concentrations of resorption and formation markers were mathematically transformed to build up plots with four fields, symbolizing fast and slow resorption and fast and slow formation processes. The reference data of bone turnover were represented by a 95% confidence ellipse. For individual marker plots, we converted data of bone turnover markers from therapy follow-up profiles of patients in a similar manner.

RESULTS

In pre-, peri- and postmenopausal women (n= 190, 39 +/- 6 years; n= 35, 51 +/- 6 years; n= 44, 55 +/- 5 years, respectively), the medians of the bone resorption marker CrossLaps and of the bone formation markers osteocalcin and aminoterminal propeptide of type I procollagen were 0.13/0.16/0.22 ng mL(-1), 21/21/25 ng mL(-1) and 36/35/45 ng mL(-1), respectively. In postmenopausal women, the marker plots revealed a shift towards accelerated bone resorption. A discrimination from osteopenic women (n= 138) failed.

CONCLUSION

The proposed marker plot facilitates the intuitive perception of bone turnover in individual patients as well as in patient groups by a synopsis of the balance between bone formation and resorption with the rate of these processes.