Age-related reference intervals for bone turnover markers from an Australian reference population

Differences in bone turnover markers and injury risks between local and international horses: A Victorian Spring Racing Carnival study

BACKGROUND

Musculoskeletal injuries (MSI) are common in racehorses and have been of increasing concern in horses travelling internationally to compete. Understanding the differences in bone turnover between local horses and international horses following long-distance air transportation may inform MSI prevention strategies.

OBJECTIVES

To understand the differences in bone turnover markers and risk of MSI between local horses and international horses following long-distance air transportation.

STUDY DESIGN

Prospective cohort.

METHODS

The concentrations of bone turnover markers (OCN and CTXI), markers of stress (cortisol), inflammation (serum amyloid A) and circadian rhythm (melatonin), and bisphosphonates were determined in blood samples collected twice (14-17 days apart), from horses following international travel (n = 69), and from local horses (n = 79). The associations between markers, long-distance travel and MSI were determined using multivariable generalised linear regression models.

RESULTS

Within 3-5 days post-transport, concentrations of cortisol in international horses were higher than those of local horses (main effect, Coef. 0.39; 95% CI 0.24, 0.54; p < 0.001) but they decreased and were not different to those of local horses at the second timepoint (interaction effect, Coef. -0.27; 95% CI -0.46, -0.07; p = 0.007). After adjusting for age and sex, OCN and CTXI were not significantly different between international and local horses; however, OCN was lower in international horses at timepoint 2 (interaction effect, Coef. -0.16; 95% CI -0.31, -0.01; p = 0.043). The prevalence of MSI was higher in the international (26%; 95% CI 16, 38%) compared with local horses (8%; 95% CI 3, 16%; p < 0.001), with all severe MSI sustained by the international horses. At the second timepoint compared with the first timepoint post-transport, cortisol remained high or increased (interaction effect, Coef. 0.43; 95% CI 0.24, 0.61; p < 0.001) and OCN increased (interaction effect, Coef. 0.26; 95% CI 0.08, 0.44; p = 0.006) in the horses that sustained severe MSI.

MAIN LIMITATIONS

Horse population and racing career parameters differed between groups. Bone turnover markers have low sensitivity to detect local bone changes.

CONCLUSIONS

Most horses showed minimal effects of long-distance air transport within 2 weeks relative to local horses as assessed by stress and bone turnover markers. Screening for persistent high cortisol and evidence of net bone formation after long-distance air transportation may help to identify racehorses at high risk of catastrophic MSI.

Rapid bone microarchitecture decline in older men with high bone turnover-the prospective STRAMBO study

Older men with high bone turnover have faster bone loss. We assessed the link between the baseline levels of bone turnover markers (BTMs) and the prospectively assessed bone microarchitecture decline in men. In 825 men aged 60-87 yr, we measured the serum osteocalcin (OC), bone alkaline phosphatase (BAP), N-terminal propeptide of type I procollagen (PINP), and C-terminal telopeptide of type I collagen (CTX-I), and urinary total deoxypyridinoline (tDPD). Bone microarchitecture and strength (distal radius and distal tibia) were estimated by high-resolution pQCT (XtremeCT, Scanco Medical) at baseline and then after 4 and 8 yr. Thirty-seven men took medications affecting bone metabolism. Statistical models were adjusted for age and BMI. At the distal radius, the decrease in the total bone mineral density (Tt.BMD), cortical BMD (Ct.BMD), cortical thickness (Ct.Thd), and cortical area (Ct.Ar) and failure load was faster in the highest vs the lowest CTX-I quartile (failure load: -0.94 vs -0.31% yr-1, P < .001). Patterns were similar for distal tibia. At the distal tibia, bone decline (Tt.BMD, Ct.Thd, Ct.Ar, Ct.BMD, and failure load) was faster in the highest vs the lowest tDPD quartile. At each skeletal site, the rate of decrease in Tb.BMD differed between the extreme OC quartiles (P < .001). Men in the highest BAP quartile had a faster loss of Tt.BMD, Tb.BMD, reaction force, and failure load vs the lowest quartile. The link between PINP and bone decline was poor. The BTM score is the sum of the nos. of the quartiles for each BTM. Men in the highest quartile of the score had a faster loss of cortical bone and bone strength vs the lowest quartile. Thus, in the older men followed prospectively for 8 yr, the rate of decline in bone microarchitecture and estimated bone strength was 50%-215% greater in men with high bone turnover (highest quartile, CTX-I above the median) compared to the men with low bone turnover (lowest quartile, CTX-I below the median).

Open-label extension of a randomized trial investigating safety and efficacy of rhPTH(1-84) in hypoparathyroidism

Hypoparathyroidism (HypoPT) is a rare disease, often inadequately controlled by conventional treatment. PARALLAX was a mandatory post-marketing trial assessing pharmacokinetics and pharmacodynamics of different dosing regimens of recombinant human parathyroid hormone 1-84 (rhPTH[1-84]) for treating HypoPT. The present study (NCT03364738) was a phase 4, 1-yr open-label extension of PARALLAX. Patients received only 2 doses of rhPTH(1-84) in PARALLAX and were considered treatment-naive at the start of the current study. rhPTH(1-84) was initiated at 50 μg once daily, with doses adjusted based on albumin-corrected serum calcium levels. Albumin-corrected serum calcium (primary outcome measure), health-related quality of life (HRQoL), adverse events, and healthcare resource utilization (HCRU) were assessed. The mean age of the 22 patients included was 50.0 yr; 81.8% were women, and 90.9% were White. By the end of treatment (EOT), 95.5% of patients had albumin-corrected serum calcium values in the protocol-defined range of 1.88 mmol/L to the upper limit of normal. Serum phosphorus was within the healthy range, and albumin-corrected serum calcium-phosphorus product was below the upper healthy limit throughout, while mean 24-h urine calcium excretion decreased from baseline to EOT. Mean supplemental doses of calcium and active vitamin D were reduced from baseline to EOT (2402-855 mg/d and 0.8-0.2 μg/d, respectively). Mean serum bone turnover markers, bone-specific alkaline phosphatase, osteocalcin, procollagen type I N-terminal propeptide, and type I collagen C-telopeptide increased 2-5 fold from baseline to EOT. The HCRU, disease-related symptoms and impact on HRQoL improved numerically between baseline and EOT. Nine patients (40.9%) experienced treatment-related adverse events; no deaths were reported. Treatment with rhPTH(1-84) once daily for 1 yr improved HRQoL, maintained eucalcemia in 95% of patients, normalized serum phosphorus, and decreased urine calcium excretion. The effects observed on urine calcium and the safety profile are consistent with previous findings.

Clinical trial identifier

NCT03364738.

Serum Markers of Bone Turnover Following Controlled Administration of Two Medical Cannabis Products in Healthy Adults

Introduction: Cannabidiol (CBD) has been shown to maintain bone integrity in pre-clinical models, but little is known about the effects of delta-9-tetrahydrocannabinol (THC) on bone turnover. In this study we explored the effects of two oral medical cannabis products on normal bone homeostasis through evaluation of markers of bone resorption (carboxyl-terminal collagen crosslinks, CTx) and bone formation (procollagen type 1 N-terminal propeptide, P1NP; alkaline phosphatase, ALP). Methods: This study is an analysis of secondary data from two Phase 1 double-blind, placebo-controlled trials of Spectrum Yellow (0.9 mg THC, 20 mg CBD/mL of oil) and Spectrum Red (2.5 mg THC, 0.3 mg CBD/softgel). Healthy participants (n=38 men, 45 women) were randomized to receive 5-20 mg THC (CBD levels varied as a function of administered product) or placebo daily (BID) for 7 days. Bone markers were assessed at baseline, upon completion of product administration (day 8), and after a 5-day washout (day 13). Results: All bone markers were significantly higher in men at baseline (p≤0.008). For CTx, there was a significant day×group interaction (F=3.23, p=0.04); CTx levels were significantly lower in participants treated with Spectrum Red (b=-164.28; 95% confidence interval [CI], -328 to -0.29; p=0.04) and marginally lower in participants treated with Spectrum Yellow (b=-157.31; 95% CI, -323 to 8.68; p=0.06) versus placebo on day 8. For P1NP and ALP, there were no significant differences between treatments across study days. Bone marker values outside the reference range (RR) were observed; CTx > RR (n=71) was predominantly (85.9%) observed in male participants, whereas P1NP > RR (n=100) was more evenly distributed between sexes (53.0% in men). These were not considered clinically significant and did not differ between treatment groups. Conclusions: These are the first interventional human data on the effect of cannabinoids on biomarkers of bone turnover. Short-term treatment with CBD- or THC-dominant medical cannabis products resulted in attenuation of a marker of bone resorption. Although the attenuation was not clinically significant, this finding may be indicative of protective properties of cannabinoids in bone. Further research over longer dosing durations in individuals exhibiting bone-specific conditions (e.g., osteoporosis) is warranted. ClinicalTrials.gov IDs: ACTRN12619001723178 and ACTRN12619001450101.

A pilot feasibility randomised controlled trial of bone antiresorptive agents on bone turnover markers in critically ill women

Critical illness is associated with increased bone turnover, loss of bone density, and increased risk of fragility fractures. The impact of bone antiresorptive agents in this population is not established. This trial examined the efficacy, feasibility, and safety of antiresorptive agents administered to critically ill women aged fifty years or greater. Women aged 50 years or greater admitted to an intensive care unit for at least 24 h were randomised to receive an antiresorptive agent (zoledronic acid or denosumab) or placebo, during critical illness and six months later (denosumab only). Bone turnover markers and bone mineral density (BMD) were monitored for 1 year. We studied 18 patients over 35 months before stopping the study due to the COVID-19 pandemic. Antiresorptive medications decreased the bone turnover marker type 1 cross-linked c-telopeptide (CTX) from day 0 to 28 by 43% (± 40%), compared to an increase of 26% (± 55%) observed with placebo (absolute difference - 69%, 95% CI - 127% to - 11%), p = 0.03). Mixed linear modelling revealed differences in the month after trial drug administration between the groups in serum CTX, alkaline phosphatase, parathyroid hormone, and phosphate. Change in BMD between antiresorptive and placebo groups was not statistically analysed due to small numbers. No serious adverse events were recorded. In critically ill women aged 50-years and over, antiresorptive agents suppressed bone resorption markers without serious adverse events. However, recruitment was slow. Further phase 2 trials examining the efficacy of these agents are warranted and should address barriers to enrolment.Trial registration: ACTRN12617000545369, registered 18th April 2017.

Serum levels of bone turnover markers including calculation of Z-scores: Data from a Dutch healthy reference cohort

Introduction

Bone turnover markers (BTM) are biochemical compounds reflecting different stages of bone metabolism. Their levels change with age and differ between males and females. This makes clinical interpretation and comparison more difficult. Therefore, our aim was to establish BTM reference values which can be used to calculate Z-scores for use in daily clinical practice.

Methods

Serum markers of collagen resorption, bone formation/regulation, collagen formation and bone mineralization (sCTX, OC, PINP and BALP, respectively) were measured in non-fasting volunteers without bone-related abnormalities. Raw data was plotted and gender-specific age cohorts were established with their respective means and standard deviations (SD). Z-scores can be calculated using these reference values to correct for the influence of age and gender on BTM.

Results

In total, 856 individuals were included of which 486 (57 %) were female. Individuals were aged between 7 and 70 years. Highest serum levels of BTM were found in childhood and puberty. Peak levels are higher in boys than girls and prevail at later ages. In adults, BTM levels decrease before reaching stable nadir levels. In adults, 10-year reference cohorts with means and SD were provided to calculate Z-scores.

Conclusion

With our data, Z-scores of sCTX, OC, PINP and BALP can be calculated using reference categories (for age and gender) of Caucasian healthy volunteers. Clinicians can use BTM Z-scores to determine whether there are changes in bone turnover physiology beyond those expected during aging. BTM Z-scores facilitate harmonization of data interpretation in daily clinical practice and research.

Skeletal site-specific effects of jump training on bone mineral density in adults: a systematic review and meta-analysis

Preserving or preventing declines in bone mineral density (BMD) is imperative. As jumping is a high-impact bone-loading action, this meta-analysis evaluated the efficacy of jump training to improve BMD and bone turnover relative to non-jumping controls in men and women > 18 years, following Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines. PubMed and COCHRANE Library databases were searched until February 2022. Fifteen articles (19 jumping-trials) met the predetermined search criteria. Eighteen trials were included for BMD data (n = 666 participants). There was a significant small-moderate effect of jumping on femoral neck BMD (%mean difference: 95%CI, +1.50%: 0.83%; 2.17%, p < 0.0001), that remained significant after sub-analysis by age for both younger (+1.81%: 0.98%; 2.65%) and older adults (+1.03%: 0.02%; 2.03%). BMD of total hip (+1.26%: 0.56%; 1.96% vs + 0.06%: -0.96%; 1.08%), and trochanter (+0.84%: 0.20%; 1.48% vs -0.16%: -1.08%; 0.76%) increased significantly with jump training only in younger adults and non-significantly at the lumbar spine (+0.84%: -0.02%; 1.7% vs -0.09%: -0.96%; 0.77%) only in younger but not older adults, respectively. The BMD response to jump training appears to be site-specific, with the highest sensitivity at the femoral neck. No dose-response effect suggests moderate certainty of a gain in femoral neck BMD when performing the median jump-load of 50 jumps four times weekly.

High-impact jumping mitigates the short-term effects of low energy availability on bone resorption but not formation in regularly menstruating females: A randomized control trial

Low energy availability (LEA) is prevalent in active individuals and negatively impacts bone turnover in young females. High-impact exercise can promote bone health in an energy efficient manner and may benefit bone during periods of LEA. Nineteen regularly menstruating females (aged 18-31 years) participated in two three-day conditions providing 15 (LEA) and 45 kcals kg fat-free mass-1  day-1 (BAL) of energy availability, each beginning 3 ± 1 days following the self-reported onset of menses. Participants either did (LEA+J, n = 10) or did not (LEA, n = 9) perform 20 high-impact jumps twice per day during LEA, with P1NP, β-CTx (circulating biomarkers of bone formation and resorption, respectively) and other markers of LEA measured pre and post in a resting and fasted state. Data are presented as estimated marginal mean ± 95% CI. P1NP was significantly reduced in LEA (71.8 ± 6.1-60.4 ± 6.2 ng mL-1 , p < 0.001, d = 2.36) and LEA+J (93.9 ± 13.4-85.2 ± 12.3 ng mL-1 , p < 0.001, d = 1.66), and these effects were not significantly different (time by condition interaction: p = 0.269). β-CTx was significantly increased in LEA (0.39 ± 0.09-0.46 ± 0.10 ng mL-1 , p = 0.002, d = 1.11) but not in LEA+J (0.65 ± 0.08-0.65 ± 0.08 ng mL-1 , p > 0.999, d = 0.19), and these effects were significantly different (time by condition interaction: p = 0.007). Morning basal bone formation rate is reduced following 3 days LEA, induced via dietary restriction, with or without high-impact jumping in regularly menstruating young females. However, high-impact jumping can prevent an increase in morning basal bone resorption rate and may benefit long-term bone health in individuals repeatedly exposed to such bouts.

Oral Cannabidiol Treatment in Two Postmenopausal Women with Osteopenia: A Case Series

Introduction: Cannabidiol (CBD), a nonintoxicating cannabinoid, may be involved in bone remodeling, but human studies are limited. In this case series, we explored the effects of oral CBD administration on bone turnover. Materials and Methods: Two postmenopausal women with osteopenia (T-score=-1 to -2.5) were randomized to receive 100 or 300 mg CBD daily (oral, bis in die [twice per day]) for 12 weeks. Serum markers of bone resorption (carboxyl-terminal collagen crosslinks [CTx]) and bone formation (procollagen type 1 N-terminal propeptide [P1NP], bone-specific alkaline phosphatase [BSAP], and osteocalcin [OC]); safety measures; plasma concentrations of CBD and metabolites; sleep disturbance; symptoms of depression, anxiety, and stress; and quality of life, were assessed. Results: CBD was well tolerated, with no clinically significant change in vital signs, hematology, chemistry, or urinalysis, and no adverse events reported. Reductions (% change vs. baseline) in CTx (-8.5%, -28.1%), P1NP (-9.9%, -39.5%), BSAP (-12.7%, -74.8%), and OC (-16.0%, -6.7%) were observed after 12 weeks of oral administration of 100 or 300 mg CBD daily, respectively. The two participants self-reported consuming 95.3% and 98.8% of CBD doses, respectively. CBD and select metabolites were measurable in plasma after 4 and 12 weeks of CBD treatment. No notable changes in sleep disturbance, depression, anxiety, stress, or quality of life were observed. Conclusions: CBD was well tolerated after 12 weeks of twice-daily oral administration and was associated with reduction in measured markers of bone turnover. Compliance with CBD treatment was good. Large-scale randomized clinical trials into the bone protective effects of CBD in postmenopausal women are warranted.

Reference intervals for plasma β-CTX and P1NP in children: a systematic review and pooled estimates

OBJECTIVE

Reference intervals for plasma P1NP and β-CTX in children and adolescents from several studies have recently been published. The aim of this study was to combine the available data into a set of reference intervals for use in clinical laboratories.

DESIGN AND METHODS

A systematic literature search for primary studies reporting reference intervals for plasma P1NP and β-CTX in infants, children and adolescents using the Roche methods was carried out. Reference limits were extracted. For each year of age, mean upper and lower reference limits were calculated, weighted by the number of subjects in each study, and were plotted against age. Proposed reference limits were developed from the weighted mean data with age partitions determined pragmatically.

RESULTS

Reference limits for clinical use for females to 25 years and males to 18 years, based on the weighted mean reference data, are presented. Ten studies contributed to the pooled analysis. The proposed reference limits are identical for males and females <9 years age, prior to the pubertal growth spurt. For β-CTX, the weighted mean reference limits showed relatively constant values during the pre-pubertal years but a marked increase during puberty before a rapid decline towards adult values. Those for P1NP showed high values declining rapidly in the first 2 years of life, followed by a modest increase during early puberty. Limited published information for late adolescent and young adult subjects was noted.

CONCLUSIONS

The proposed reference intervals may be useful for clinical laboratories reporting these bone turnover markers measured by the Roche assays.

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 mass and biomarkers in young women with anorexia nervosa: a prospective 3-year follow-up study

INTRODUCTION

Anorexia nervosa (AN) increases the risk of impaired bone health, low areal bone mineral density (aBMD), and subsequent fractures. This prospective study investigated the long-term effects of bone and mineral metabolism on bone and biomarkers in 22 women with AN.

MATERIALS AND METHODS

Body composition and aBMD were measured by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography. Total and free 25-hydroxyvitamin D (25OHD), C-terminal collagen cross-links (CTX), osteocalcin, bone-specific alkaline phosphatase (BALP), leptin, sclerostin, and oxidized/non-oxidized parathyroid hormone (PTH) were analyzed before and after 12 weeks of intensive nutrition therapy and again 3 years later. An age-matched comparison group of 17 healthy women was recruited for the 3-year follow-up.

RESULTS

Body mass index (BMI) and fat mass increased from baseline to 3 years in women with AN. Sclerostin decreased during nutrition therapy and further over 3 years, indicating reduced bone loss. CTX was elevated at baseline and after 12 weeks but decreased over 3 years. BALP increased during nutrition therapy and stabilized over 3 years. Free 25OHD was stable during treatment but decreased over 3 years. Non-oxidized PTH was stable during treatment but increased over 3 years. Trabecular volumetric BMD in AN patients decreased during the first 12 weeks and over 3 years despite stable BMI and bone biomarkers implying increased BMD.

CONCLUSION

Our findings highlight the importance of early detection and organized long-term follow-up of bone health in young women with a history of AN.

Osteoglycin Across the Adult Lifespan

CONTEXT

Osteoglycin (OGN) is a proteoglycan released from bone and muscle which has been associated with markers of metabolic health. However, it is not clear whether the levels of circulating OGN change throughout the adult lifespan or if they are associated with clinical metabolic markers or fitness.

OBJECTIVE

We aimed to identify the levels of circulating OGN across the lifespan and to further explore the relationship between OGN and aerobic capacity as well as OGN's association with glucose and HOMA-IR.

METHODS

107 individuals (46 males and 61 females) aged 21-87 years were included in the study. Serum OGN levels, aerobic capacity (VO2peak), glucose, and homeostatic model assessment for insulin resistance (HOMA-IR) were assessed. T-tests were used to compare participant characteristics between sexes. Regression analyses were performed to assess the relationship between OGN and age, and OGN and fitness and metabolic markers.

RESULTS

OGN displayed a nonlinear, weak "U-shaped" relationship with age across both sexes. Men had higher levels of OGN than women across the lifespan (β = 0.23, P = .03). Age and sex explained 16% of the variance in OGN (adjusted R2 = 0.16; P < .001). Higher OGN was associated with higher VO2peak (β = 0.02, P = .001); however, those aged <50 showed a stronger positive relationship than those aged >50. A higher OGN level was associated with a higher circulating glucose level (β = 0.17, P < .01). No association was observed between OGN and HOMA-IR.

CONCLUSION

OGN was characterized by a U-shaped curve across the lifespan which was similar between sexes. Those with a higher aerobic capacity or higher glucose concentration had higher OGN levels. Our data suggest an association between OGN and aerobic fitness and glucose regulation. Future studies should focus on exploring the potential of OGN as a biomarker for chronic disease.

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.

Analysis of serum bone turnover markers in female cynomolgus monkeys of different ages

OBJECTIVE

The purpose of this study was to examine bone turnover markers, estradiol, parathyroid hormone, and 25 hydroxyvitamin D, in cynomolgus monkeys at different ages to improve our understanding of the changes in bone turnover markers throughout the life cycle of cynomolgus monkeys and to provide a basis for the establishment of a non-human primate model of osteoporosis.

METHODS

Total Body Bone Mineral Density and Total Body Bone Mineral Content were measured using Dual-Energy X-Ray Absorptiometry in cynomolgus monkeys at different ages. Serum bone turnover marker' levels were measured using enzyme immunoassays at each age group, and the relationship between bone turnover markers and age was assessed by Spearman rank correlation analysis to investigate the relationship between bone turnover markers and age in female cynomolgus monkeys.

RESULTS

Total Body Bone Mineral Density in female cynomolgus monkeys peaked at 10 years of age and then formed a plateau that was maintained until old age. Procollagen I Aminoterminal Propeptide, Bone Alkaline Phosphatase, Osteocalcin, and C-Terminal Telopeptide Of Type I Collagen peaked at 1 to 3 years of age and gradually decreased with age, leveling off by 10 years of age. Estradiol, parathyroid hormone, and 25 hydroxyvitamin D, follicle-stimulating hormone, luteinizing hormone, were not significantly different among age groups.

CONCLUSION

This paper provides data on trends in bone turnover markers throughout the life cycle of female cynomolgus monkeys, which are similar to human changes.

Age-related trends and reference intervals of cross-linked C-telopeptide of type I collagen and procollagen type I N-propeptide from a reference population of Sri Lankan adult women

Refer ence values of bone turnover markers (BTMs) are determined by factors that are country-specific. In Sri Lanka, unavailability of BTM reference data has led to their non-use in management of osteoporosis. The results of this study can be used as reference data for women in Sri Lanka.

INTRODUCTION

This study was performed to establish age-related reference intervals for bone resorption marker; cross-linked C-telopeptide of type I collagen (CTX) and bone formation marker; procollagen type I N-propeptide (PINP) in a group of Sri Lankan adult women.

METHODS

Adult women (n = 347) aged 20-70 years were recruited using age-stratified random sampling technique and categorized into age groups by decades. Serum CTX and PINP concentration were measured using enzyme-linked immunosorbent assay (ELISA). The geometric mean (95% confidence interval) and 2.5th and 97.5th percentiles were calculated. ANOVA was used to compare the means between groups.

RESULTS

Mean CTX levels were relatively low and remained unchanged between 20 and 49 years. After the age of 49 years, mean CTXconcentration elevated significantly until the age of 70 years (43%, p < 0.001). Mean PINP concentrations were not significantly different between age categories (p > 0.05). Reference intervals of CTX and PINP were based on 2.5th and 97.5th percentile values. Reference intervals of CTX for the age groups of 20-29, 30-39, 40-49, 50-59, and 60-70 years were 0.19-0.97 ng/mL, 0.18-0.95 ng/mL, 0.20-1.29 ng/mL, 0.17-2.20 ng/mL, and 0.17-2.85 ng/mL respectively. Reference intervals of PINP for the same age groups were 118-810 pg/mL, 119-772 pg/mL, 116-645 pg/mL, 108-684 pg/mL, and 108-715 pg/mL respectively.

CONCLUSION

In Sri Lanka, bone turnover markers are not used in evaluating patients mainly due to lack of normative data. These values can be used as reference data for women in this age group.

Age-related changes and reference intervals of RANKL, OPG, and bone turnover markers in Indian women

RANKL and OPG are cytokines involved in bone remodeling that makes them potential bone biomarkers. The reference interval for these cytokines, their ratio, and bone turnover markers CTX and PINP were established in Indian women, which may serve in diagnosis and management of osteoporosis.

PURPOSE

The aim of the study was to establish reference interval for RANKL, OPG, RANKL/OPG, and bone turnover markers CTX and PINP in healthy Indian women.

METHODS

This was a cross-sectional study on 374 healthy Indian women in the age group of 20-65 years. Serum levels of total RANKL, OPG, CTX, PINP, and estradiol were determined by commercial ELISA kits. The reference intervals for these cytokines and bone turnover markers were based on the 95% centrally distributed data.

RESULTS

Median RANKL (245.6 pmol/L vs. 149 pmol/L) and RANKL/OPG (38.7 vs. 20.4) were higher, while sCTX (380 ng/L vs. 551 ng/L) and OPG levels (6.1 pmol/L vs. 7.4 pmol/L) were lower in premenopausal women than those in postmenopausal women. PINP levels were comparable in both groups. Women were classified into 5 groups according to decades of age and the reference intervals for RANKL, OPG, RANKL/OPG ratio, and CTX and PINP in each group were reported.

CONCLUSION

We reported menopausal status-based and age-related reference intervals for serum RANKL, OPG, RANKL/OPG ratio, and CTX and PINP in healthy Indian women.

A Multi-Institutional Randomized Controlled Trial to Investigate Whether Zoledronate Prevents Bone Loss After Discontinuation of Denosumab: The Study Protocol of Denosumab Sequential Therapy (DST) Trial

Background: Though denosumab is an effective treatment for osteoporosis, the rebound effect after discontinuation has drawn investigators' attention. It includes a dramatic loss of gained bone mineral density (BMD) and an increased risk of vertebral fractures. This prospective multi-institutional randomized controlled trial aims to investigate whether zoledronate prevents loss of BMD after discontinuation of denosumab. The trial was registered as Denosumab Sequential Therapy (DST) trial in March 2019 at clinicaltrials.gov, with the identifier NCT03868033.

Methods: The study is conducted at National Taiwan University Hospital and its branches. Patients who have continuously received denosumab treatment for two or more years are surveyed for eligibility. Baseline characteristics and questionnaires of life quality are recorded after recruitment. BMD, circulating levels of bone turnover markers (BTMs), including serum N-terminal propeptide of type 1 collagen (P1NP) and C-terminal telopeptide (CTX), are checked before the stratified randomization to 4 groups. Biological sex and the T-scores are used to create 4 strata. The participants in group 1 adhere to regular denosumab therapy for another 2 years. All the other patients receive on-time zoledronate treatment in the first year. The participants in group 2, 3, and 4 have on-time denosumab, on-time zoledronate and drug holiday in the second year, respectively. BMDs are checked annually. Pre-scheduled checkpoints of BTMs are also arranged. For patient safety, rescue treatment with another injection of zoledronate will be applied to the patients on drug holiday if the CTX levels raise above the pre-specified threshold, 0.573 ng/mL for women and 0.584 ng/mL for men. The primary outcomes are the percentage changes of BMDs in lumbar spine, total hip and femoral neck. The secondary outcomes include the changes of serum level of the BTMs, new osteoporotic fractures, extra zoledronate injections needed in group 4 and the differences of quality of life.

Discussion: We aim to provide evidence whether zoledronate prevents bone loss after denosumab cessation. To our knowledge, the study has the largest sample size. No other randomized controlled study included all the three different treatment strategies and a positive control. It is also the first associated randomized controlled trial outside Europe.

Age- and sex-specific concentrations of bone remodeling markers in healthy Indian adults with and without vitamin D deficiency

Bone remodeling markers exhibit marked inter-ethnic variation; hence, population-specific data are required. Herein, we have established age- and sex-specific concentrations of serum PINP and CTX in healthy Indian adults with and without vitamin D deficiency that can be used in clinical practice for monitoring response to anti-osteoporotic therapy.

OBJECTIVE

The present study was undertaken to generate data on age- and sex-specific concentrations of serum procollagen type I N-propeptide (PINP) and type I collagen C-telopeptide (CTX) in healthy Indian adults with and without vitamin D deficiency.

METHODS

Apparently, healthy subjects aged ≥ 20 years with no prior co-morbidities were recruited from the community by door-to-door surveys. Provisionally eligible participants underwent blood sampling after overnight fast. Individuals with biochemical abnormalities that could potentially affect bone remodeling were excluded. However, subjects with vitamin D deficiency were not excluded. Serum total PINP and β-CrossLaps (CTX) were measured using electro-chemiluminescence immunoassay.

RESULTS

After exclusion, 677 subjects were enrolled (M:F = 2.5:4.2, mean age = 45.0 years). Median serum PINP and CTX were 55.78 ng/ml (40.27-71.70) and 0.356 ng/ml (0.238-0.499), respectively. There was no difference in PINP/CTX between men and women or between premenopausal and postmenopausal women. Decade-wise distribution of PINP/CTX showed that maximum values were attained in 3rd decade; subsequently, in men, levels declined with age while in women, there was a peak in the 6th decade coinciding with the early years of menopause. Vitamin D deficiency and severe vitamin D deficiency were seen in 417 (61.5%) and 259 subjects (38.2%), respectively. There was no significant difference in PINP/CTX in subjects with and without vitamin D deficiency.

CONCLUSIONS

The present study has allowed us to generate data on serum concentrations of PINP/CTX in a diverse group of healthy community-dwelling Indian adults with varying serum vitamin D levels. It might aid in monitoring response to anti-osteoporotic therapy amongst native Indians.

Effects of abiraterone acetate plus prednisone on bone turnover markers in chemotherapy-naïve mCRPC patients after ADT failure: A prospective analysis of the italian real-world study ABITUDE

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Bone remodeling is disrupted in metastatic disease, affecting > 70% of mCRPC men.

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In metastatic disease, abnormal levels of specific BTMs are released.

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We prospectively measured four BTMs markers in chemotherapy-naïve mCRPC men on AAP therapy.

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AAP seems to act on the microenvironment of metastatic but not of normal bone.

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This action likely contributes to the antitumoral activity of AAP.

Background

Bone remodeling is disrupted in metastatic disease, which affects > 70% of metastatic castration-resistant prostate cancer (mCRPC) patients. As a result, abnormal levels of specific bone turnover biomarkers (BTMs) are released. In this prospective ancillary analysis of the Italian real-world study ABITUDE, four markers were measured during abiraterone acetate plus prednisone (AAP) treatment in chemotherapy-naïve mCRPC men failing androgen-deprivation therapy.

Methods

Patients were enrolled if a blood sample was obtained before the first administration of abiraterone (baseline); ad-hoc blood samples were withdrawn during routine tests after 3, 6, and 12 months. A centralized lab measured bone alkaline phosphatase (BALP, osteoblast activity marker), type-I collagen-C-telopeptide (CTX-1, bone resorption marker), parathyroid hormone (PTH) and vitamin D (vitD). At each time point, intra-patient variations vs baseline were compared by the signed-rank test (statistical significance: P-value < 0.05).

Results

Of 481 patients enrolled in ABITUDE, 186 (median age: 76 [range: 53–93] years) met the substudy criteria: 74.7% had bone metastases, 11.8% were on bone-targeted therapies (BTT) and 14.0% on vitD supplementation. BALP decreased significantly at month 6 (P = 0.0010) and 12 (P < 0.0001) and CTX-1 at month 6 (P = 0.0028); PTH increased at month 3 (P < 0.0001); no significant difference in vitD levels was observed. Similar findings were observed in BTT-untreated patients. The reduction in BALP and CTX-1 levels was more pronounced in patients with than without bone metastases; in the latter group, no significant variation in BALP and CTX-1 levels was observed.

Conclusions

AAP seems to exert an effect on the microenvironment of metastatic but not of normal bone, which likely contributes to its antitumoral activity.

Fusion Potential of Human Osteoclasts In Vitro Reflects Age, Menopause, and In Vivo Bone Resorption Levels of Their Donors-A Possible Involvement of DC-STAMP

It is well established that multinucleation is central for osteoclastic bone resorption. However, our knowledge on the mechanisms regulating how many nuclei an osteoclast will have is limited. The objective of this study was to investigate donor-related variations in the fusion potential of in vitro-generated osteoclasts. Therefore, CD14⁺ monocytes were isolated from 49 healthy female donors. Donor demographics were compared to the in vivo bone biomarker levels and their monocytes’ ability to differentiate into osteoclasts, showing that: (1) C-terminal telopeptide of type I collagen (CTX) and procollagen type I N-terminal propeptide (PINP) levels increase with age, (2) the number of nuclei per osteoclast in vitro increases with age, and (3) there is a positive correlation between the number of nuclei per osteoclast in vitro and CTX levels in vivo. Furthermore, the expression levels of the gene encoding dendritic cell-specific transmembrane protein (DCSTAMP) of osteoclasts in vitro correlated positively with the number of nuclei per osteoclast, CTX levels in vivo, and donor age. Our results furthermore suggest that these changes in gene expression may be mediated through age-related changes in DNA methylation levels. We conclude that both intrinsic factors and age-induced increase in fusion potential of osteoclasts could be contributing factors for the enhanced bone resorption in vivo, possibly caused by increased expression levels of DCSTAMP.

Markers of Bone Health and Impact of Whey Protein Supplementation in Army Initial Entry Training Soldiers: A Double-Blind Placebo-Controlled Study

Training civilians to be soldiers is a challenging task often resulting in musculoskeletal injuries, especially bone stress injuries. This study evaluated bone health biomarkers (P1NP/CTX) and whey protein or carbohydrate supplementations before and after Army initial entry training (IET). Ninety male IET soldiers participated in this placebo-controlled, double-blind study assessing carbohydrate and whey protein supplementations. Age and fat mass predicted bone formation when controlling for ethnicity, explaining 44% (p < 0.01) of bone formation variations. Age was the only significant predictor of bone resorption (p = 0.02) when controlling for run, fat, and ethnicity, and these factors together explained 32% of the variance in bone resorption during week one (p < 0.01). Vitamin D increased across training (p < 0.01). There was no group by time interaction for supplementation and bone formation (p = 0.75), resorption (p = 0.73), Vitamin D (p = 0.36), or calcium (p = 0.64), indicating no influence of a supplementation on bone biomarkers across training. Age, fitness, fat mass, and ethnicity were important predictors of bone metabolism. The bone resorption/formation ratio suggests IET soldiers are at risk of stress injuries. Male IET soldiers are mildly to moderately deficient in vitamin D and slightly deficient in calcium throughout training. Whey protein or carbohydrate supplementations did not affect the markers of bone metabolism.

Effect of Vitamin D Levels on Bone Remodeling in Healthy Women

BACKGROUND

Vitamin D deficiency is prevalent among Indian women. Subclinical vitamin D deficiency is a significant risk factor for osteopenia and fractures. However, its effect on bone metabolism and bone mineral density (BMD) is still debatable.

OBJECTIVES

This study aimed to determine relationships of the vitamin D status with bone turnover markers, carboxy-terminal telopeptide of type-I collagen (CTX), N-terminal propeptide of type I procollagen (PINP), and BMD in healthy Indian women.

METHODS

In this cross-sectional study, we determined serum levels of 25-hydroxy vitamin D (25(OH)D), parathyroid hormone, serum CTX, and PINP using commercial ELISA kits in 310 healthy Indian women aged 25 - 65 years who underwent BMD measurements with DXA scan.

RESULTS

The prevalence of vitamin D deficiency was 53.87% and vitamin D insufficiency 31.29%. A direct correlation of BMD with vitamin D levels was not observed. PINP negatively correlated with vitamin D in both premenopausal (Spearman's r = -0.169, P < 0.05) and postmenopausal (Spearman's r = -0.241, P < 0.05) women. However, CTX positively correlated with vitamin D in both premenopausal (Spearman's r = 0.228, P < 0.01) and postmenopausal (Spearman's r = 0.244, P < 0.05) women.

CONCLUSIONS

Vitamin D deficiency is more prevalent in premenopausal women than in postmenopausal ones. Although vitamin D does not show any association with BMD, it affects bone remodeling, which is reflected by changes in the bone formation marker PINP and the bone resorption marker CTX.

Reference Intervals for Bone Turnover Markers in Korean Healthy Women

Background

Adequate suppression of bone turnover rate is important to decrease fracture risk without mineralization defect due to oversuppression. This study was performed to determine reference intervals (RIs) for 2 bone turnover markers, serum C-terminal telopeptide of type I collagen (CTX) and osteocalcin, in Korean women.

Methods

A total of 461 Korean women (287 premenopausal and 174 postmenopausal) without any disease or drug history affecting bone metabolism was included. Serum CTX and osteocalcin were measured after overnight fasting. Bone mineral density (BMD) was measured at the 1st to 4th lumbar vertebra using dual energy X-ray absorptiometry. Subjects with normal spinal BMD (T-score ≥-1.0) were included in this study.

Results

After stable concentrations were maintained, both CTX and osteocalcin were abruptly increased in 50 to 59 years, and then decreased with increasing age. Median levels and interquartile range of serum CTX and osteocalcin in all subjects were 0.322 (0.212-0.461) ng/mL and 15.68 (11.38-19.91) ng/mL. RIs for serum CTX and osteocalcin in all subjects were 0.115 to 0.861 ng/mL and 6.46 to 36.76 ng/mL. Those were higher in postmenopausal women (CTX, 0.124-1.020 ng/mL, osteocalcin, 5.42-41.57 ng/mL) than in premenopausal women (CTX, 0.101-0.632 ng/mL, osteocalcin, 6.73-24.27 ng/mL). If we use target reference levels as lower half of premenopausal 30 to 45 years in patients with antiresorptive drugs, those were 0.101 to 0.251 ng/mL and 6.40 to 13.36 ng/mL.

Conclusions

We established RIs for serum CTX and osteocalcin in healthy Korean women with normal lumbar spine BMD. Premenopausal RIs for serum CTX and osteocalcin would be useful to monitor patients with low bone mass using osteoporosis drugs.

Osteoporosis in South-East Asian Countries

Osteoporosis (OP) is a condition where there is low bone density and microarchitectural deterioration which can predispose to fragility fractures. There is a wealth of literature on OP from the developed countries, but less so from Asia. This review will explore the field of OP research in South-East Asia with regard to the epidemiology, the diagnosis of OP and the role of laboratory tests in the management of OP, with emphasis on 25-dihydroxyvitamin D and bone turnover markers.

Osteocalcin and its forms across the lifespan in adult men

PURPOSE

Osteocalcin (OC), an osteoblast-specific secreted protein expressed by mature osteoblasts, is used in clinical practice and in research as a marker of bone turnover. The carboxylated (cOC) and undercarboxylated (ucOC) forms may have a different biological function but age-specific reference ranges for these components are not established. Given the different physiological roles, development of reference ranges may help to identify people at risk for bone disease.

METHODS

Blood was collected in the morning after an overnight fast from 236 adult men (18 to 92 years old) free of diabetes, antiresorptive, warfarin or glucocorticoid use. Serum was analyzed for total osteocalcin (tOC) and the ucOC fraction using the hydroxyapatite binding method. cOC, ucOC/tOC and cOC/tOC ratios were calculated. Reference intervals were established by polynomial quantile regression analysis.

RESULTS

The normal ranges for young men (≤30 years) were: tOC 17.9-56.8 ng/mL, ucOC 7.1-22.0 ng/mL, cOC 8.51-40.3 ng/mL (2.5th to 97.5th quantiles). Aging was associated with a "U" shaped pattern for tOC, cOC and ucOC levels. ucOC/tOC ratio was higher, while cOC/tOC ratio was lower in men of advanced age. Age explained ∼31%, while body mass index explained ∼4%, of the variance in the ratios.

CONCLUSIONS

We have defined normal reference ranges for the OC forms in Australian men and demonstrated that the OC ratios may be better measures, than the absolute values, to identify the age-related changes on OC in men. These ratios may be incorporated into future research and clinical trials, and their associations with prediction of events, such as fracture or diabetes risk, should be determined.

Viewpoint on the role of tissue maintenance in ageing: focus on biomarkers of bone, cartilage, muscle, and brain tissue maintenance

Specific hallmarks are thought to underlie the ageing process and age-related functional decline. In this viewpoint, we put forward the hypothesis that disturbances in the process of tissue maintenance are an important common denominator that may lie in between specific hallmarks of ageing (i.e. damage and responses to damage) and their ultimate (patho)physiological consequences (i.e. functional decline and age-related disease). As a first step towards verifying or falsifying this hypothesis, it will be important to measure biomarkers of tissue maintenance in future studies in different study populations. The main aim of the current paper is to discuss potential biomarkers of tissue maintenance that could be used in such future studies. Among the many tissues that could have been chosen to explore our hypothesis, to keep the paper manageable, we chose to focus on a selected number of tissues, namely bone, cartilage, muscle, and the brain, which are important for mobility and cognition and affected in several common age-related diseases, including osteoporosis, osteoarthritis, sarcopenia, and neurodegenerative diseases. Furthermore, we discuss the advantages and limitations of potential biomarkers for use in (pre)clinical studies. The proposed biomarkers should be validated in future research, for example by measuring these in humans with different rates of ageing.

Association between dairy intake and fracture in an Australian-based cohort of women: a prospective study

OBJECTIVE

Given the inconsistent evidence on dairy consumption and risk of fracture, we assessed the association between milk/total dairy consumption and major osteoporotic fracture (MOF) in women from the Geelong Osteoporosis Study (GOS).

METHODS

Women aged ≥50 years (n=833) were followed from baseline (1993-1997) to date of first fracture, death or 31 December 2017, whichever occurred first. Dairy consumption was assessed by self-report at baseline and the follow-up phases. MOFs (hip, forearm, clinical spine and proximal humerus) were confirmed radiologically. Multivariable-adjusted Cox proportional hazard models were used to determine associations between milk/total dairy (milk, cheese, yoghurt, ice cream) consumption and MOFs. Cross-sectional associations between milk/total dairy consumption and serum high-sensitivity C reactive protein (hsCRP), C-terminal telopeptide (CTx) and procollagen type 1 N-terminal propeptide (P1NP) at baseline were investigated using multivariable linear regression.

RESULTS

During follow-up (11 507 person-years), 206 women had an MOF. Consuming >500 mL/d of milk was not significantly associated with increased HR for MOF. Non-milk (1.56; 95% CI 0.99 to 2.46) drinkers and consumption of ≥800 g/d total dairy (1.70; 95% CI 0.99 to 2.93) had marginally higher HR for MOF compared with consuming <250 mL/d of milk and 200-399 g/d of total dairy, respectively. Milk consumption was inversely associated with serum hsCRP and CTx, but total dairy consumption was not associated with these serum markers.

CONCLUSION

Higher milk consumption did not increase the risk for MOF in older women. However, a trend for increased MOF was detected in zero milk and higher total dairy consuming women.

Bone Turnover Markers in Men and Women with Impaired Fasting Glucose and Diabetes

Bone turnover markers (BTMs) are reduced in diabetes, but whether BTM changes occur in impaired fasting glucose (IFG) is unknown. The aim of this study was to investigate whether BTMs are altered in IFG and diabetes compared to normoglycaemia. For men and women (n = 2222) in the Geelong Osteoporosis Study, IFG was defined as fasting plasma glucose (FPG) 5.5-6.9 mmol/L and diabetes as FPG ≥ 7.0 mmol/L, use of antihyperglycemic medication and/or self-report. Serum C-terminal telopeptide (CTx) and procollagen type 1 N-terminal propeptide (P1NP) were measured. After natural log transformation to normalise the data, multivariable regression was used to examine the relationship between glycaemia status and bone turnover markers (BTMs), before and after adjusting for other confounders. There were 643 men and 682 women with normoglycaemia, 355 men and 391 women with IFG and 97 men and 54 women with diabetes. Men with IFG or diabetes had lower adjusted ln(CTx) and ln(P1NP) compared to normoglycaemia (all p < 0.05). Women with IFG or diabetes had lower adjusted ln(CTx) and ln(P1NP) (all p < 0.05) except for ln(P1NP) when comparing diabetes with normoglycaemia, which showed a trend for lower ln(P1NP) (p = 0.053). In both sexes, an age * glycaemia interaction term indicated between-group differences in BTMs diminished with increasing age. No other confounders were identified. Bone turnover was lower in those with either IFG or diabetes compared to normoglycaemia.

The 24-hour serum profiles of bone markers in healthy older men and women

The process of bone turnover displays variations over 24 h, with C-terminal cross-linked telopeptide of type 1 collagen (CTX) and osteocalcin exhibiting a nadir in the afternoon and a peak in the night. In contrast, N-terminal propeptide of type 1 procollagen (P1NP) did not display an apparent 24-hour rhythm. Other emerging novel biomarkers of bone, sclerostin and Dickkopf-related protein 1 (DKK1), are markers of osteocyte activity with limited data available regarding their 24-hour profiles. In this study, we aimed to extend available data on 24-hour profiles of CTX, osteocalcin, and P1NP and to assess the 24-hour profiles of sclerostin and DKK1 in healthy older men and women and to compare these between men and women. We measured these five bone markers in EDTA plasma collected every 4 h during 24 h in 37 healthy older men and women (range 52-76 years). Differences between time points were determined using repeated measures ANOVA and cosinor analyses were performed to determine circadian rhythmicity. The circadian rhythm of CTX was confirmed by the cosinor model, with women showing larger amplitude compared to men. Osteocalcin showed higher levels during nighttime compared to daytime in both men and women. For P1NP levels we observed a small but significant increase in the night in men. Sclerostin and DKK1 did not show a circadian rhythm, but sclerostin levels differed between time points. Because of the large intraindividual variation, DKK1 as measured in this study cannot be considered a reliable marker for diagnostic or research purposes. In conclusion, when measuring CTX, osteocalcin, P1NP, or sclerostin either in clinical practice or in a research setting, one should consider the 24-hour profiles of these bone markers.

Potential role of senescence in radiation-induced damage of the aged skeleton

Human aging-related changes are exacerbated in cases of disease and cancer, and conversely aging is a catalyst for the occurrence of disease and multimorbidity. For example, old age is the most significant risk factor for cancer and among people who suffer from cancer, >60% are above the age of 65. Oxidative stress and DNA damage, leading to genomic instability and telomere dysfunction, are prevalent in aging and radiation-induced damage and are major cellular events that lead to senescence. Human exposures from nuclear fallout, cosmic radiation and clinical radiotherapy (RT) are some common sources of irradiation that affect bone tissue. RT has been used to treat malignant tumors for over a century, but the effects of radiation damage on tumor-adjacent normal tissue has largely been overlooked. There is an increase in the percent survivorship among patients post-RT, and it is in older survivors where the deleterious synergy between aging and radiation exposure conspires to promote tissue deterioration and dysfunction which then negatively impacts their quality of life. Thus, an aging skeleton is already pre-disposed to architectural deterioration, which is further worsened by radiation-induced bone damage. Effects of senescence and the senescence associated secretory phenotype (SASP) have been implicated in age-associated bone loss, but their roles in radiation-associated bone damage are still elusive. RT is used in treatment for a variety of cancers and in different anatomical locations, the sequelae of which include long-term morbidity and lifelong discomfort. Therefore, consideration of the growing evidence that implicates the role of senescence in radiation-induced bone damage argues in favor of exploiting current senotherapeutic approaches as a possible prevention or treatment.

Clinical practice update on testosterone therapy for male hypogonadism: Contrasting perspectives to optimize care

US Endocrine Society (ES) published a clinical practice guideline on testosterone therapy in men with hypogonadism, and Endocrine Society of Australia (ESA) a position statement on management of male hypogonadism. Both emphasize the importance of diagnosing men who are androgen deficient due to organic (classical or pathological) hypogonadism arising from disorders of the hypothalamus, pituitary or testes, who assuredly benefit from testosterone therapy. Both recognize that men with an intact gonadal axis may have low testosterone concentrations, for instance older men or men with obesity or other medical comorbidities. ES guidelines classify such symptomatic men as having organic (advanced age) or functional (obesity, medical comorbidities) hypogonadism, giving an option for testosterone therapy as a shared decision between clinicians and individual patients. ESA did not recommend testosterone therapy in these men. ES offers a reference range for total testosterone established in young men, while ESA cites age-standardized reference ranges. ES recommends using free testosterone as well as total testosterone to identify men with hypogonadism in conditions where sex hormone-binding globulin (SHBG) is altered, or when total testosterone is borderline. ESA recommends confirmatory biochemical testing with total testosterone, recognizing that this may be lower than expected if SHBG concentrations are low. Both emphasize the importance of identifying pre-existing prostate and cardiovascular disease prior to initiating testosterone therapy, with ES providing specific recommendations for PSA measurement, deferring testosterone therapy after major cardiovascular events and indications for pituitary imaging. These contrasting approaches highlight gaps in the evidence base where individualized patient management is required.

Age-related Reference Intervals for Total Collagen-I-N-terminal Propeptide in Healthy Korean Population

Background

Procollagen type I N-terminal propeptide (PINP) is one of the most clinically useful bone formation biomarkers. Therefore, the purpose of this study was to independently evaluate the performance of automated total PINP assay and established age- and gender-specific reference intervals for PINP in healthy Korean population.

Methods

The imprecision, linearity, and detection capability of Elecsys total PINP assay was determined and reference interval was established using 599 serums from Korean population with normal bone mineral densities based on bone densitometry. Age groups were divided into 20s, 30s, 40s, 50s, 60s and over.

Results

Elecsys total PINP had excellent performance in imprecision, linearity, and detection capability. When partitioning age groups in Korean male and female populations, there was significant difference in total PINP between different age groups. In male populations, PINP level was decreased with increasing age, then it remained steady after middle-age. In female populations, there was a decreasing tendency similar to that in the male population with a sharp increase in the 50 to 59 age group.

Conclusions

Elecsys total PINP assay showed precise and reliable performance in our study. We established age-related PINP reference intervals for Korean male and female population with normal bone mineral densities.

Use of bone turnover markers in the management of osteoporosis

PURPOSE OF REVIEW

Osteoporosis is a common public health problem that is often undertreated and underdiagnosed. The clinical management of osteoporosis is often reactionary to devastating fracture events. Bone turnover markers may improve the ease and rapidity at which osteoporosis is monitored and treated. Bone turnover markers are biochemical byproducts of bone formation or bone resorption. The clinical use of bone turnover markers is limited by significant preanalytical variability. Effective interpretation of bone turnover markers requires a detailed understanding of the variables that can affect their responses to osteoporosis treatment and monitoring.

RECENT FINDINGS

Progress is continuously being made on the standardization of bone turnover markers. The literature on the response of bone turnover markers to unique clinical situations is expanding. Data for evidence-based reference intervals for bone turnover markers has increased. Variables that affect the appropriate timing of lab draws like diurnal variation, postprandial status, exercise and alcohol use have been described. Studies examining the expected response of bone turnover markers to treatments of osteoporosis and other medications that affect bone health continue to increase.

SUMMARY

Bone turnover markers have clinical utility in the comprehensive evaluation of osteoporosis. When interpreted with caution and with a good understanding of their natural variability, bone turnover markers provide information that supplements osteoporosis management and provides useful clinical information about conditions that alter bone turnover.

A 10-Year Prospective Study of Bone Mineral Density and Bone Turnover in Males and Females With Type 1 Diabetes

CONTEXT

In a previous community-based, cross-sectional study, males with type 1 diabetes (T1D) had lower bone mineral density (BMD) than did matched people without diabetes but females with T1D had normal BMD.

OBJECTIVE

To determine whether BMD in the males continued to decline, the neutral effect of T1D on BMD in females persisted, and whether temporal BMD changes reflected changes in bone turnover markers.

DESIGN

Longitudinal observational study.

SETTING

Urban community.

PATIENTS

Forty-eight of the original 102 original cross-sectional study participants (20 males, 28 females) of mean age 42.0 years and median diabetes duration 14.6 years at baseline who were restudied a mean of 10.3 years later.

MAIN OUTCOME MEASURES

BMD at total hip, femoral neck, lumbar spine (L1 to L4), and distal forearm. Biochemical bone turnover markers.

RESULTS

After adjustment for age, body mass index (BMI), and renal function, there was no temporal change in BMD at the hip or forearm in the males (P ≥ 0.12), but lumbar spine BMD increased (P = 0.009). Females exhibited no statistically significant change in BMD in similar multivariable models that also included postmenopausal status, except a mild increase at the forearm (P = 0.046). Age- and sex-related changes in bone turnover markers paralleled those in general population studies.

CONCLUSIONS

There is a reduction in BMD in males with T1D that occurs early in the course of the disease but then stabilizes. BMD in females with T1D remains similar to that expected for age, BMI, and postmenopausal status.

Bone Turnover Markers Are Not Associated With Hip Fracture Risk: A Case-Control Study in the Women's Health Initiative

Current guidelines recommend that serum C-terminal telopeptide of type I collagen (CTX) and serum procollagen type 1 aminoterminal propeptide (PINP), measured by standardized assays, be used as reference markers in observational and interventional studies. However, there are limited data to determine whether serum CTX and PINP are associated with hip fracture risk among postmenopausal women. We determined the associations of serum CTX and serum PINP with hip fracture risk among postmenopausal women aged 50 to 79 years at baseline. We performed a prospective case-control study (400 cases, 400 controls) nested in the Women's Health Initiative Observational Study, which enrolled participants at 40 US clinical centers. Cases were women with incident hip fracture not taking osteoporosis medication; hip fractures were confirmed using medical records. Untreated controls were matched by age, race/ethnicity, and date of blood sampling. Serum CTX and serum PINP were analyzed on 12-hour fasting blood samples. The main outcome measure was incident hip fracture risk (mean follow-up 7.13 years). After adjustment for body mass index, smoking, frequency of falls, history of fracture, calcium and vitamin D intake, and other relevant covariates, neither serum CTX level nor serum PINP level was statistically significantly associated with hip fracture risk (CTX p_trend  = 0.22, PINP p_trend  = 0.53). Our results do not support the utility of serum CTX level or PINP level to predict hip fracture risk in women in this age group. These results will inform future guidelines regarding the potential utility of these markers in fracture prediction. © 2018 American Society for Bone and Mineral Research.

Bone metabolism in patients with anorexia nervosa and amenorrhoea

PURPOSE

Aim of this study is focusing on bone metabolism in AN patients with amenorrhoea and related estrogen deficiency effects.

METHODS

AN patients were compared both with healthy females and with postmenopausal women (reference model for estrogen deficiency). The study sample included 81 females with AN. Laboratory tests [25-OH vitamin D, bone turnover markers, intact parathyroid hormone, sclerostin (SOST) and dickkopf-related protein (DKK1)] and dual energy X-ray absorptiometry (DXA) were taken into account.

RESULTS

AN patients had higher levels of C-terminal telopeptide of type I collagen (CTX) than both control groups. AN adolescents had CTX higher than AN young adults. In postmenopausal women, intact N-propeptide of type I collagen was higher if compared with each other group. In AN groups, Dickkopf-related protein 1 was significantly lower than the two control groups. No differences were found in sclerostin except in adolescents. In AN adolescents, DXA values at femoral sites were higher than in AN young adults and a positive correlation was found with body weight (p < 0.01) and with fat mass evaluated using DXA (p < 0.01).

CONCLUSIONS

AN women with amenorrhoea have an increased bone resorption like postmenopausal women but bone formation is depressed. The consequent remodeling uncoupling is considerably more severe than that occurring after menopause.

Changes in bone turnover markers with HIV seroconversion and ART initiation

Background

Osteoporosis is common among HIV-infected persons and contributes to risk of fragility fracture. While ART initiation is associated with decreases in bone mineral density and increases in bone turnover, the impact of HIV on bone metabolism is unclear.

Methods

We identified men at the Chicago site of the Multicenter AIDS Cohort Study who HIV seroconverted while under observation. Concentrations of 25-OH vitamin D, bone turnover markers [procollagen type 1 N terminal propeptide (P1NP), osteocalcin (OC), C-telopeptide (CTX)] and sclerostin were measured from stored serum obtained at pre-HIV infection, pre-ART and post-ART initiation timepoints. Mixed models, with each biomarker as an outcome, were fitted. Timepoint, age, CD4 count (cells/mm 3 ), HIV-viral suppression, season and an age by timepoint interaction term were considered as fixed effects.

Results

Data from 52 participants revealed that median duration between HIV seroconversion and ART initiation was 8.7 years (IQR 3.7-11.6). Median CD4 and plasma HIV-RNA concentrations were 445 (IQR 298.5-689) and 20 184 copies/mL (IQR 6237-64 340), respectively, at the pre-ART timepoint. Multivariate analyses demonstrated pre-HIV infection levels of OC that were higher than pre-ART levels (6.8 versus 5.7 ng/mL, P  =   0.04); and pre-ART levels of sclerostin that were higher than post-ART levels (0.033 versus 0.02 ng/mL, P  <0.001). No changes in P1NP, CTX and 25-OH vitamin D levels were detected.

Conclusions

HIV seroconversion was associated with decreased OC levels while ART initiation was associated with decreases in sclerostin, a negative regulator of bone formation. Our results suggest that both HIV infection and ART have an impact on bone metabolism in white men.

Bone Turnover Status: Classification Model and Clinical Implications

Aim: To develop a practical model for classification bone turnover status and evaluate its clinical usefulness. Methods: Our classification of bone turnover status is based on internationally recommended biomarkers of both bone formation (N-terminal propeptide of type1 procollagen, P1NP) and bone resorption (beta C-terminal cross-linked telopeptide of type I collagen, bCTX), using the cutoffs proposed as therapeutic targets. The relationships between turnover subtypes and clinical characteristic were assessed in1223 hospitalised orthogeriatric patients (846 women, 377 men; mean age 78.1±9.50 years): 451(36.9%) subjects with hip fracture (HF), 396(32.4%) with other non-vertebral (non-HF) fractures (HF) and 376 (30.7%) patients without fractures. Resalts: Six subtypes of bone turnover status were identified: 1 - normal turnover (P1NP>32 μg/L, bCTX≤0.250 μg/L and P1NP/bCTX>100.0[(median value]); 2- low bone formation (P1NP ≤32 μg/L), normal bone resorption (bCTX≤0.250 μg/L) and P1NP/bCTX>100.0 (subtype2A) or P1NP/bCTX<100.0 (subtype 2B); 3- low bone formation, high bone resorption (bCTX>0.250 μg/L) and P1NP/bCTX<100.0; 4- high bone turnover (both markers elevated ) and P1NP/bCTX>100.0 (subtype 4A) or P1NP/bCTX<100.0 (subtype 4B). Compared to subtypes 1 and 2A, subtype 2B was strongly associated with nonvertebral fractures (odds ratio [OR] 2.0), especially HF (OR 3.2), age>75 years and hyperparathyroidism. Hypoalbuminaemia and not using osteoporotic therapy were two independent indicators common for subtypes 3, 4A and 4B; these three subtypes were associated with in-hospital mortality. Subtype 3 was associated with fractures (OR 1.7, for HF OR 2.4), age>75 years, chronic heart failure (CHF), anaemia, and history of malignancy, and predicted post-operative myocardial injury, high inflammatory response and length of hospital stay (LOS) above10 days. Subtype 4A was associated with chronic kidney disease (CKD), anaemia, history of malignancy and walking aids use and predicted LOS>20 days, but was not discriminative for fractures. Subtype 4B was associated with fractures (OR 2.1, for HF OR 2.5), age>75 years, CKD and indicated risks of myocardial injury, high inflammatory response and LOS>10 days. Conclusions: We proposed a classification model of bone turnover status and demonstrated that in orthogeriatric patients altered subtypes are closely related to presence of nonvertebral fractures, comorbidities and poorer in-hospital outcomes. However, further research is needed to establish optimal cut points of various biomarkers and improve the classification model.

The role of carboxy-terminal cross-linking telopeptide of type I collagen, dual x-ray absorptiometry bone strain and Romberg test in a new osteoporotic fracture risk evaluation: A proposal from an observational study

The consolidated way of diagnosing and treating osteoporosis in order to prevent fragility fractures has recently been questioned by some papers, which complained of overdiagnosis and consequent overtreatment of this pathology with underestimating other causes of the fragility fractures, like falls. A new clinical approach is proposed for identifying the subgroup of patients prone to fragility fractures. This retrospective observational study was conducted from January to June 2015 at the Nuclear Medicine-Bone Metabolic Unit of the of the Fondazione IRCCS Ca' Granda, Milan, Italy. An Italian population of 125 consecutive postmenopausal women was investigated for bone quantity and bone quality. Patients with neurological diseases regarding balance and vestibular dysfunction, sarcopenia, past or current history of diseases and use of drugs known to affect bone metabolism were excluded. Dual X-ray absorptiometry was used to assess bone quantity (bone mineral density) and bone quality (trabecular bone score and bone strain). Biochemical markers of bone turnover (type I collagen carboxy-terminal telopeptide, alkaline phosphatase, vitamin D) have been measured. Morphometric fractures have been searched by spine radiography. Balance was evaluated by the Romberg test. The data were evaluated with the neural network analysis using the Auto Contractive Map algorithm. The resulting semantic map shows the Minimal Spanning Tree and the Maximally Regular Graph of the interrelations between bone status parameters, balance conditions and fractures of the studied population. A low fracture risk seems to be related to a low carboxy-terminal cross-linking telopeptide of type I collagen level, whereas a positive Romberg test, together with compromised bone trabecular microarchitecture DXA parameters, appears to be strictly connected with fragility fractures. A simple assessment of the risk of fragility fracture is proposed in order to identify those frail patients at risk for osteoporotic fractures, who may have the best benefit from a pharmacological and physiotherapeutic approach.

Bone turnover marker determinants in young women: results from the Safe-D study

Background Bone turnover markers (BTMs) may provide insight into bone health in young women, but have been little studied in this demographic. We aimed to explore the association between body composition, hormonal contraception, bone mineral density and biochemical parameters and BTMs in young women. Methods Participants were community-dwelling females aged 16-25 years, living in Victoria, Australia. Carboxy-terminal cross-linking telopeptide of type 1 collagen (CTX) and total procollagen type 1 N-propeptide (P1NP) were analysed on the Roche Elecsys automated analyzer. A total of 305 were evaluated, after excluding participants with medical conditions or medications (except hormonal contraceptives), which may affect bone metabolism. Results Median (Q1, Q3) BTM values were 540 (410, 690) ng/L for CTX and 61.7 (46.2, 83.7) µg/L for P1NP. Serum CTX and P1NP were inversely associated with chronological age ( P < 0.001), transferrin ( P < 0.020) and serum dehydroepiandrosterone sulphate concentration ( P < 0.001). BTM values were up to 22% lower in combined oral contraceptive (COC) pill users ( P < 0.001). Serum CTX was inversely associated with per cent body fat ( P = 0.009) and tibial cortical volumetric bone mineral density (vBMD; P = 0.003). Serum P1NP concentrations were 23  µg/L higher in participants who reported using an osteopath in the previous year ( P = 0.007). Conclusions These data suggest that BTMs are influenced by age, COC use, body composition, iron status and hormonal profiles. Higher CTX values were associated with lower tibial cortical vBMD. Examining BTMs in relation to interventions aimed at improving bone health in young women is warranted.

Effects of reduced energy availability on bone metabolism in women and men

BACKGROUND

The short-term effects of low energy availability (EA) on bone metabolism in physically active women and men are currently unknown.

PURPOSE

We evaluated the effects of low EA on bone turnover markers (BTMs) in a cohort of women and a cohort of men, and compared effects between sexes.

METHODS

These studies were performed using a randomised, counterbalanced, crossover design. Eleven eumenorrheic women and eleven men completed two 5-day protocols of controlled (CON; 45kcal·kgLBM^-1·d^-1) and restricted (RES; 15kcal·kgLBM^-1·d^-1) EAs. Participants ran daily on a treadmill at 70% of their peak aerobic capacity (VO₂ peak) resulting in an exercise energy expenditure of 15kcal·kgLBM^-1·d^-1 and consumed diets providing 60 and 30kcal·kgLBM^-1·d^-1. Blood was analysed for BTMs [β-carboxyl-terminal cross-linked telopeptide of type I collagen (β-CTX) and amino-terminal propeptide of type 1 procollagen (P1NP)], markers of calcium metabolism [parathyroid hormone (PTH), albumin-adjusted calcium (ACa), magnesium (Mg) and phosphate (PO₄)] and regulatory hormones [sclerostin, insulin-like growth factor 1 (IGF-1), triiodothyronine (T₃), insulin, leptin, glucagon-like-peptide-2 (GLP-2)].

RESULTS

In women, β-CTX AUC was significantly higher (P=0.03) and P1NP AUC was significantly lower (P=0.01) in RES compared to CON. In men, neither β-CTX (P=0.46) nor P1NP (P=0.12) AUCs were significantly different between CON and RES. There were no significant differences between sexes for any BTM AUCs (all P values>0.05). Insulin and leptin AUCs were significantly lower following RES in women only (for both P=0.01). There were no differences in any AUCs of regulatory hormones or markers of calcium metabolism between men and women following RES (all P values>0.05).

CONCLUSIONS

When comparing within groups, five days of low EA (15kcal·kgLBM^-1·d^-1) decreased bone formation and increased bone resorption in women, but not in men, and no sex specific differences were detected.

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.

Comparison of two automated assays of BTM (CTX and P1NP) and reference intervals in a Danish population

Bone turnover markers are used for monitoring osteoporosis treatment. Therefore, we evaluated the agreement between different assays for CTX and PINP and established reference intervals in a cohort of 2300 individuals. We found poor agreement between assays and different reference intervals. This highlights the importance of harmonization of the assays.

INTRODUCTION

Two reference markers for bone turnover have been proposed: CTX bone resorption and P1NP for bone formation. The purpose of the current study was to establish reference intervals for the two markers in a Danish cohort and to determine the agreement on the two platforms.

METHODS

Fasting sera from 2308 individuals (1250 males and 1058 females, age range 24-76 years) participating in the Health2006 study were analyzed for CTX and P1NP using the automated IDS-iSYS analyzer and the automated Cobas e411 analyzer. Participants in anti-osteoporotic treatment were excluded, while subjects on hormonal contraceptives were included.

RESULTS

There was significant disagreement between both the two P1NP assays with a mean difference of -3 μg/L (LoA -19 to 14) (p < 0.001) and the two CTX assays with a mean difference of 13 ng/L (LoA-187 to 214) (p < 0.001). For CTX, there was a systematic bias: at low values, Cobas measured a higher value than iSYS and at higher concentrations, iSYS measured increasingly higher values than Cobas. Based on the results, we propose three reference intervals for each sex: 25-29, 30-39, and 40-80 years for men, and 25-29, >30 (pre-menopausal), and >30 years (post-menopausal) for women.

CONCLUSIONS

There is significant disagreement between the IDS-iSYS and Roche Cobas assays for both reference markers. Consequently, the reference intervals for an adult, healthy population are different depending on the analysis method used. Therefore, repeated measurements of patient samples used for monitoring of treatment should be done on the same assay. Moreover, assay-specific reference intervals should be used. Harmonization of assays for BTM is highly warranted.

Measurement and Clinical Utility of βCTX in Serum and Plasma

Biochemical markers of bone turnover (BTM) are released during bone remodeling and can be measured in blood or urine as noninvasive surrogate markers for the bone remodeling rate. The C-terminal cross-linked telopeptide of type I collagen (βCTX) is released during bone resorption and is specific to bone tissue. Assays have been developed to measure βCTX in blood and in urine; most current use of βCTX measurement for research and in clinical practice is performed on a blood sample. Method-specific differences for serum and plasma βCTX have led to initiatives to standardize or harmonize βCTX commercial assays. βCTX demonstrates significant biological variation due to circadian rhythm and effect of food which can be minimized by standardized sample collection in the fasting state in the morning. While βCTX predicts fracture risk independent of bone mineral density, lack of data has precluded its inclusion in fracture risk calculators. The changes seen in βCTX with antiresorptive therapies have been well characterized and this has led to its widespread use for monitoring therapy in osteoporosis. However, more fracture-based data on appropriate treatment goals for monitoring need to be developed. Evidence is lacking for the use of βCTX in managing "drug holidays" of bisphosphonate treatment in osteoporosis or risk stratifying those at increased risk of developing osteonecrosis of the jaw. βCTX is useful as an adjunct to imaging techniques for the diagnosis of Paget's disease of bone and for monitoring therapy and detecting recurrence. βCTX also shows promise in the management of metastatic bone disease.

Bone structure in two adult subjects with impaired minor spliceosome function resulting from RNU4ATAC mutations causing microcephalic osteodysplastic primordial dwarfism type 1 (MOPD1)

Microcephalic osteodysplastic primordial dwarfism type 1 (MOPD1), or Taybi-Linder syndrome is characterized by distinctive skeletal dysplasia, severe intrauterine and postnatal growth retardation, microcephaly, dysmorphic features, and neurological malformations. It is an autosomal recessive disorder caused by homozygous or compound heterozygous mutations in the RNU4ATAC gene resulting in impaired function of the minor spliceosome. Here, we present the first report on bone morphology, bone density and bone microstructure in two adult MOPD1 patients and applied radiographs, dual energy X-ray absorptiometry, high-resolution peripheral quantitative computed tomography and biochemical evaluation. The MOPD1 patients presented with short stature, low BMI but normal macroscopic bone configuration. Bone mineral density was low. Compared to Danish reference data, total bone area, cortical bone area, cortical thickness, total bone density, cortical bone density, trabecular bone density and trabecular bone volume per tissue volume (BV/TV) were all low. These findings may correlate to the short stature and low body weight of the MOPD1 patients. Our findings suggest that minor spliceosome malfunction may be associated with altered bone modelling.

Changes in Bone Mineral Density in the Year after Critical Illness

RATIONALE

Critical illness may be associated with increased bone turnover and loss of bone mineral density (BMD). Prospective evidence describing long-term changes in BMD after critical illness is needed to further define this relationship.

OBJECTIVES

To measure the change in BMD and bone turnover markers (BTMs) in subjects 1 year after critical illness compared with population-based control subjects.

METHODS

We studied adult patients admitted to a tertiary intensive care unit (ICU) who required mechanical ventilation for at least 24 hours. We measured clinical characteristics, BTMs, and BMD during admission and 1 year after ICU discharge. We compared change in BMD to age- and sex-matched control subjects from the Geelong Osteoporosis Study.

MEASUREMENTS AND MAIN RESULTS

Sixty-six patients completed BMD testing. BMD decreased significantly in the year after critical illness at both femoral neck and anterior-posterior spine sites. The annual decrease was significantly greater in the ICU cohort compared with matched control subjects (anterior-posterior spine, -1.59%; 95% confidence interval, -2.18 to -1.01; P < 0.001; femoral neck, -1.20%; 95% confidence interval, -1.69 to -0.70; P < 0.001). There was a significant increase in 10-year fracture risk for major fractures (4.85 ± 5.25 vs. 5.50 ± 5.52; P < 0.001) and hip fractures (1.57 ± 2.40 vs. 1.79 ± 2.69; P = 0.001). The pattern of bone resorption markers was consistent with accelerated bone turnover.

CONCLUSIONS

Critically ill individuals experience a significantly greater decrease in BMD in the year after admission compared with population-based control subjects. Their bone turnover biomarker pattern is consistent with an increased rate of bone loss.

Bone turnover marker reference intervals in young females

Background

The use of bone turnover markers in clinical practice and research in younger people is limited by the lack of normative data and understanding of common causes of variation in bone turnover marker values in this demographic. To appropriately interpret bone turnover markers, robust reference intervals specific to age, development and sex are necessary. This study aimed to determine reference intervals of bone turnover markers in females aged 16–25 years participating in the Safe-D study.

Methods

Participants were recruited through social networking site Facebook and were asked to complete an extensive, online questionnaire and attend a site visit. Participants were tested for serum carboxy-terminal cross-linking telopeptide of type 1 collagen and total procollagen type 1 N-propeptide using the Roche Elecsys automated analyser. Reference intervals were determined using the 2.5th to 97.5th percentiles of normalized bone turnover marker values.

Results

Of 406 participants, 149 were excluded due to medical conditions or medication use (except hormonal contraception) which may affect bone metabolism. In the remaining 257 participants, the reference interval was 230–1000 ng/L for serum carboxy-terminal cross-linking telopeptide of type 1 collagen and 27–131  µg/L for procollagen type 1 N-propeptide. Both marker concentrations were inversely correlated with age and oral contraceptive pill use. Therefore, intervals specific to these variables were calculated.

Conclusions

We defined robust reference intervals for cross-linking telopeptide of type 1 collagen and procollagen type 1 N-propeptide in young females grouped by age and contraceptive pill use. We examined bone turnover markers’ relationship with several lifestyle, clinical and demographic factors. Our normative intervals should aid interpretation of bone turnover markers in young females particularly in those aged 16 to 19 years where reference intervals are currently provisional.

Clinical usefulness of bone turnover marker concentrations in osteoporosis

Current evidence continues to support the potential for bone turnover markers (BTM) to provide clinically useful information particularly for monitoring the efficacy of osteoporosis treatment. Many of the limitations identified earlier remain, principally in regard to the relationship between BTM and incident fractures. Important data are now available on reference interval values for CTX and PINP across a range of geographic regions and for individual clinical assays. An apparent lack of comparability between current clinical assays for CTX has become evident indicating the possible limitations of combining such data for meta-analyses. Harmonization of units for reporting serum/plasma CTX (ng/L) and PINP (μg/L) is recommended. The development of international collaborations continues with an important initiative to combine BTM results from clinical trials in osteoporosis in a meta-analysis and an assay harmonization program are likely to be beneficial. It is possible that knowledge derived from clinical studies can further enhance fracture risk estimation tools with inclusion of BTM together with other independent risk factors. Further data of the relationships between the clinical assays for CTX and PINP as well as physiological and pre-analytical factors contributing to variability in BTM concentrations are required.