Are bone turnover markers associated with volumetric bone density, size, and strength in older men and women? The AGES-Reykjavik study

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).

Reduced trabecular bone mineral density and thinner cortices in men with distal forearm fractures

Men with distal forearm fractures have reduced bone density, an increased risk of osteoporosis and of further fractures. The aim of the study was to investigate the structural determinants of these observations using quantitative CT (qCT). Ninety six men with low-trauma distal forearm fracture and 101 age-matched healthy control subjects were recruited. All subjects underwent a quantitative CT on a standard 64-slice whole body CT scanner. These were analysed on Mindways QCT PRO™ Software to generate volumetric and geometric data at the lumbar spine, femoral neck and total hip, ultra-distal and distal 33 % radius. Biochemical investigations, health questionnaires and measurements of bone turnover were made. Men with fracture had significantly lower total and trabecular vBMD at all sites. The greatest percentage reduction was at the ultra-distal radius (13.5 % total and 11.7 % trabecular vBMD). In the fracture group cortical vBMD was significantly higher in the femoral neck (p < 0.001) and maintained at the ultra-distal radius compared with control subjects. However, cortical cross-sectional area (CSA) and thickness were significantly reduced at the femoral neck (p < 0.001 and p = 0.002 respectively) and forearm sites (CSA ultradistal radius p = 0.001, cortical thickness p = 0.002, CSA distal one third radius p = 0.045 and cortical thickness p = 0.005). Cross sectional moment of inertia (CSMI) and section moduli were significantly reduced at the femoral neck (CSMI1 p = 0.002, CSMI2 p = 0.012 and section moduli Z1 p < 0.001, Z2 p = 0.004) and the ultra-distal radius (CSMI1 p = 0.008 and section moduli Z1 p = 0.018, Z2 p = 0.007). In stepwise logistic regression analysis distal forearm fracture showed the strongest association with a model comprising ultra-distal forearm trabecular vBMD (negative), procollagen type I N-terminal propeptide (PINP, positive) and sex hormone binding globulin (SHBG, negative). In conclusion, these observations explain the structural reasons for the increased fracture risk in men with distal forearm fractures.

Accelerated decline in quadriceps area and Timed Up and Go test performance are associated with hip fracture risk in older adults with impaired kidney function

OBJECTIVE

This study aimed to examine whether an accelerated decline in quadriceps cross-sectional area (CSA), attenuation (a surrogate of quality), and strength, as well as lower limb muscular function, are associated with hip fractures in older adults with impaired kidney function.

DESIGN

Prospective population-based study.

SETTING

Community-dwelling old population in Reykjavik, Iceland.

SUBJECTS

A total of 875 older adults (mean baseline age 76 years) from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study with impaired kidney function.

METHODS

Quadriceps CSA and density were determined using computed tomography (CT), knee extension strength was measured with an isometric dynamometer chair, and muscular function was assessed using the Timed Up and Go (TUG) test. All muscle-related measurements were assessed twice over a mean follow-up of 5.2 years. Data on hip fracture incidence was obtained from medical records during a maximum of 8.4 years of follow-up time.

RESULTS

Fully adjusted cox-proportional hazard regression models showed that a faster decline in quadriceps CSA and TUG test performance were significantly associated with increased hip fracture risk (HR = 1.55, 95% CI = 1.02-2.36, and HR = 1.80, 95% CI = 1.19-2.72, respectively). A faster decrease in quadriceps density and isometric knee extension strength were not associated with fracture risk.

CONCLUSIONS

Accelerated decline in CT-derived quadriceps CSA and muscular function, as measured by the TUG test's performance, are predictive of hip fracture risk in older adults with impaired kidney function. TUG test is a simple measure and easily included in routine medical examinations, compared to CT scans, which seems to be useful for identifying a subgroup of individuals with high risk of fracture.

Association of higher bone turnover with risk of curve progression in adolescent idiopathic scoliosis

OBJECTIVE

Emerging evidence suggest abnormal bone metabolism and defective bone qualities are associated to etipathogenesis of Adolescent Idiopathic Scoliosis (AIS). Systemic low bone mass is important prognosticator to predict risk of curve progression in AIS. The underlying mechanism is still unclear. We hypothesize that aberrant bone turnover correlates with bone qualities in AIS and associates to risk of curve progression.

SUBJECTS AND METHODS

Two cohorts were included in this study. The case-control study recruited 161 AIS girls and 161 ethnic/age-matched healthy girls. The longitudinal cohort recruited 128 AIS girls with two-year follow-up. Areal bone mineral density (BMD) at femoral necks were measured with dual-energy x-ray absorptiometry (DXA), and bone qualities of distal radius by high-resolution peripheral quantitative computed tomography (HR-pQCT). Time-lapse analysis of registered HR-pQCT images estimated local bone remodeling quantitatively. Serum levels of CTX and P1NP were measured with ELISA kits.

RESULTS

AIS presented significantly higher serum level of P1NP. In both AIS and control, the negative correlations were consistently observed between serum CTX/P1NP levels and most cortical bone quality parameters after adjustment to age. Significant correlation between serum bone turnover markers and trabecular bone parameters have been observed only in control. Progressive AIS has significant increase of serum P1NP level at first clinic visit. Time lapse register analysis showed high bone resorption and low net bone gain was associated with risk of progression in AIS.

CONCLUSIONS

Our study characterized AIS with higher serum bone turnover markers, which may contribute to defective bone qualities in AIS. For the first time, we showed that progressive AIS had higher systemic bone turnover markers level and local bone remodeling. This fresh evidence indicated association between disrupted bone turnover and risk of progression of AIS, which set the foundation of new prognostic method and of novel treatment target to curve progression. This study demonstrated the importance of bone metabolism in developing disease management of AIS to achieve goal of early prediction and non-surgical modulation.

Cigarette Smoking Is Associated With Lower Quadriceps Cross-sectional Area and Attenuation in Older Adults

INTRODUCTION

In addition to well-established links with cardiovascular and respiratory diseases, cigarette smoking may affect skeletal muscle; however, associations with quadriceps atrophy, density, and function are unknown. This study explored the associations of current and former smoking with quadriceps muscle area and attenuation as well as muscle force (assessed as knee extension peak torque) and rate of torque development-a measure of muscle power in older adults.

METHODS

Data from 4469 older adults, aged 66-95 years at baseline in the Age, Gene/Environment Susceptibility-Reykjavik Study with measurements of thigh computed tomography, isometric knee extension testing, self-reported smoking history, and potential covariates were analyzed.

RESULTS

Sex differences were observed in these data; therefore, our final analyses are stratified by sex. In men, both former smokers and current smokers had lower muscle area (with β= -0.10, 95% confidence interval [CI] = -0.17 to -0.03 and β = -0.19, 95% CI = -0.33 to -0.05, respectively) and lower muscle attenuation (ie, higher fat infiltration, β = -0.08, 95% CI = -0.16 to -0.01 and β = -0.17, 95% CI = -0.34 to -0.01, respectively) when compared with never smokers. Smoking status was not associated with male peak torque or rate of torque development. In women, current smoking was associated with lower muscle attenuation (β = -0.24, 95% CI = -0.34 to -0.13) compared to never smoking. Among female smokers (current and former), muscle attenuation and peak torque were lower with increasing pack-years.

CONCLUSIONS

Results suggest that cigarette smoking is related to multiple muscle properties at older age and that these relationships may be different among men and women.

IMPLICATIONS

This article presents novel data, as it examined for the first time the relationship between smoking and computed tomography-derived quadriceps muscle size (cross-sectional area) and attenuation. This study suggests that current cigarette smoking is related to higher muscle fat infiltration, which may have significant health implications for the older population, because of its known association with poor physical function, falls, and hip fractures.

Vertebral Fractures in Type 2 Diabetes Patients: Utility of Trabecular Bone Score and Relationship With Serum Bone Turnover Biomarkers

BACKGROUND

Patients with type 2 diabetes (T2D) have an increased risk for vertebral fracture (VF). The aim of this study is to determine the utility of trabecular bone score (TBS) in T2D patients with VF and the relationship of TBS with serum bone turnover biomarkers (SBTBs).

METHODOLOGY

Postmenopausal T2D female patients were prospectively enrolled. All patients received: (1) dual-energy X-ray absorptiometry exam for bone mineral density (BMD), T-score, and TBS values; (2) lateral lumbar spine radiographs for VF assessment; and (3) SBTBs: bone specific alkaline phosphatase and Beta-C-Terminal telopeptides. BMD, T-score, TBS, and SBTBs were tested for association with VF.

RESULTS

The study included 285 T2D patients (mean age = 61.1 years) and 32 patients had VF (11.2%). TBS had the strongest association with VF in T2D patients (area under curve 0.775). The TBS cutoff values for VF are 1.279 in T-score ≥1 and 1.236 in T-score <-1. In patients without VF, all sites of BMD and TBS are significantly associated with SBTBs, but in patients with VF, no associations are found between SBTBs and all sites of BMD and TBS.

CONCLUSIONS

TBS can assess bone quality in the spine. The low TBS cutoff values for T2D patients with VF imply T2D does impair bone quality. Thus, TBS should be incorporated in VF risk assessment in T2D patients. In addition, a dissociated relationship between BMD and TBS with SBTBs represents imbalanced bone turnover rate and results in bone fragility and VF.

A bone resorption marker as predictor of rate of change in femoral neck size and strength during the menopause transition

We assessed whether a bone resorption marker, measured early in the menopause transition (MT), is associated with change in femoral neck size and strength during the MT. Higher levels of bone resorption were associated with slower increases in femoral neck size and faster decreases in femoral neck strength.

PURPOSE

Composite indices of the femoral neck's ability to withstand compressive (compression strength index, CSI) and impact (impact strength index, ISI) forces integrate DXA-derived femoral neck width (FNW), bone mineral density (BMD), and body size. During the menopause transition (MT), FNW increases, and CSI and ISI decrease. This proof-of-concept study assessed whether a bone resorption marker, measured early in the MT, is associated with rates of change in FNW, CSI and ISI during the MT.

METHODS

We used previously collected bone resorption marker (urine collagen type I N-telopeptide [U-NTX]) and femoral neck strength data from 696 participants from the Study of Women's Health Across the Nation (SWAN), a longitudinal study of the MT in a multi-ethnic cohort of community-dwelling women.

RESULTS

Adjusted for MT stage (pre- vs. early perimenopause), age, body mass index (BMI), bone resorption marker collection time, and study site in multivariable linear regression, bone resorption in pre- and early perimenopause was not associated with transmenopausal decline rate in femoral neck BMD. However, each standard deviation (SD) increase in bone resorption level was associated with 0.2% per year slower increase in FNW (p = 0.03), and 0.3% per year faster declines in CSI (p = 0.02) and ISI (p = 0.01). When restricted to women in early perimenopause, the associations of bone resorption with change in FNW, CSI, and ISI were similar to those in the full sample.

CONCLUSIONS

Measuring a bone resorption marker in pre- and early perimenopause may identify women who will experience the greatest loss in bone strength during the MT.

BONE HEALTH, MUSCLE STRENGTH AND LEAN MASS: RELATIONSHIPS AND EXERCISE RECOMMENDATIONS

ABSTRACT Although muscle strength, lean mass and bone mineral content/density (BMC/BMD) are consistently reported as major outcomes of resistance training (RT), there is still no agreement on the RT regimen that is capable of achieving this result in men and women of different ages. This study describes the effects of RT on muscle strength, lean mass and bone mineralization, highlighting the relationships between them and analyzing the effectiveness of the RT protocol. Information searches were conducted in open access online academic libraries, using the BMC/BMD indices combined with muscle strength, body composition, and resistance exercises. The results showed changes in BMC/BMD in 72% of the studies published in the last decade. Among these, 77% recommended loads ≥ 80% 1-RM, 61% involved older individuals (> 60 years) and 61% had planning protocols of between 3 and 5 months (~12-20 weeks). The results also highlight muscle strength as a promising index of variations in BMC/BMD, with a moderate to high level of association (r2>0.5), which are specific for men and women in relation to the body region with best responsiveness. Among the studies published in last decade, about 61% had protocols involving only RT, and of these, 82% observed combined changes in BMC/BMD, body composition and muscle strength. This review therefore concludes that RT is important for improving muscle strength, increasing lean mass (whole-body and regional) and preventing risk factors that could impair the mineral integrity of the bone tissue, in individuals of all ages and sexes. Level of Evidence I; Systematic review of Level I RCTs (and study results were homogenous).

Osteoarthritis Changes Hip Geometry and Biomechanics Regardless of Bone Mineral Density—A Quantitative Computed Tomography Study

We aimed to compare proximal femur geometry and biomechanics in postmenopausal women with osteoarthritis (OA) and/or osteoporosis (OP), using quantitative computed tomography (QCT). A retrospective analysis of QCT scans of the proximal femur of 175 postmenopausal women was performed. Morphometric and densitometric data of the proximal femur were used to evaluate its biomechanics. We found, 21 had a normal bone mineral density (BMD), 72 had osteopenia, and 81 were diagnosed with OP. Radiographic findings of hip OA were seen in 43.8%, 52.8%, and 39.5% of the normal BMD, osteopenic, and OP groups, respectively (p < 0.05). OA was significantly correlated with total hip volume (r = 0.21), intertrochanteric cortical volume (r = 0.25), and trochanteric trabecular volume (r = 0.20). In each densitometric group, significant differences in hip geometry and BMD were found between the OA and non-OA subgroups. Hip OA and OP often coexist. In postmenopausal women, these diseases coexist in 40% of cases. Both OA and OP affect hip geometry and biomechanics. OA does so regardless of densitometric status. Changes are mostly reflected in the cortical bone. OA leads to significant changes in buckling ratio (BR) in both OP and non-OP women.

MUSCULAR STRENGTH AND REGIONAL LEAN MASS INFLUENCE BONE MINERAL HEALTH AMONG YOUNG FEMALES

ABSTRACT Introduction: Strength training is able to stimulate bone tissue metabolism by increasing mechanical stress on the skeletal system. However, the direct relationship is not yet well established among younger women, since it is necessary to describe which strength enhancement level is able to produce effective changes in bone integrity. Objectives: This study analyzed the influence of muscle strength on bone mineral content (BMC) and bone mineral density (BMD) among female college students. Methods: Fifteen women (24.9 ± 7.2 years) were assessed for regional and whole-body composition by dual-energy X-ray absorptiometry (DXA). The one-repetition maximum (1-RM) tests were assessed on flat bench press (BP), lat pulldown (LPD), leg curl (LC), knee extension (KE), and 45 degree leg press (45LP). Linear regression analyzed the relationships of BMC/BMD with regional composition and 1-RM test values. Measures of dispersion and error (R2 adj and SEE) were tested, defining a p-value of 0.05. Results: The mean value of whole-body BMC was 1925.6 ± 240.4 g and the BMD was 1.03 ± 0.07 g/cm2. Lean mass (LM) was related to BMC (R2 adj = 0.86, p<0.01, and SEE = 35.6 g) and BMD (R2 adj = 0.46, p<0.01, SEE = 0.13 g) in the lower limbs (LL). The 1-RM tests in BP were associated with BMC and BMD (R2 adj = 0.52, p<0.01, SEE = 21.4 g, and R2 adj = 0.68, p<0.01, SEE = 0.05 g/cm2, respectively) in the upper limbs, while the 1-RM tests in KE were related to BMC and BMD (R2 adj = 0.56, p<0.01. SEE = 62.6 g, and R2 adj = 0.58, p<0.01, SEE = 0.11 g/cm2, respectively) in the lower limbs. Conclusions: Hence, the 1-RM tests for multi-joint exercises are relevant to the regional BMC/BMD, reinforcing the need to include resistance exercises in training routines with the purpose of improving muscular strength and regional lean mass, thereby ensuring a healthy bone mineral mass. Level of Evidence II; Development of diagnostic criteria in consecutive patients (with applied reference ‘‘gold’’ standard).

Cigarette smoking and hip volumetric bone mineral density and cortical volume loss in older adults: The AGES-Reykjavik study

This study aimed to explore the relationships of several indicators of cigarette smoking habits (smoking status, pack-years, age at smoking initiation and smoking cessation) with quantitative computed tomographic (QCT)-derived proximal femur bone measures (trabecular vBMD, integral vBMD and the ratio of cortical to total tissue volume (cvol/ivol)) and with subsequent change in these measures over the next five years. A total of 2673 older adults (55.9% women), aged 66-92 years at baseline from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, who had two QCT scans of the hip were studied. In multivariable linear regression models, compared to never-smokers, current smokers had lower cvol/ivol at baseline and former-smokers had poorer measures on all outcomes (lower trabecular vBMD, integral vBMD and cvol/ivol), even when adjusted for several potential confounders. Further, among former smokers, those with higher pack-years had worse bone outcomes and those with longer duration since smoking cessation had better bone health at baseline. Analyses of change in bone measures revealed that compared to never-smokers, current smokers had significantly greater loss of trabecular vBMD, integral vBMD, and cvol/ivol. The regression models included adjustment for sex, age, education, and baseline body mass index, creatinine, % weight change from age 50, 25OHD, physical activity level, high-sensitive C-Reactive protein levels, alcohol and coffee consumption, history of diabetes mellitus, arthritis, and respiratory diseases. In conclusion, both current and former smoking showed adverse associations with bone health assessed with QCT. Results suggest that current smoking in particular may aggravate the rate of bone loss at older age and highlight implications for targeting this risk factor in populations that present higher smoking prevalence and vulnerability to bone fragility.

Muscle strength and regional lean body mass influence on mineral bone health in young male adults

The relationship between muscle strength and bone mineral content (BMC) and bone mineral density (BMD) is supposed from the assumption of the mechanical stress influence on bone tissue metabolism. However, the direct relationship is not well established in younger men, since the enhancement of force able to produce effective changes in bone health, still needs to be further studied. This study aimed to analyze the influence of muscle strength on BMC and BMD in undergraduate students. Thirty six men (24.9 ± 8.6 y/o) were evaluated for regional and whole-body composition by dual energy X-ray absorptiometry (DXA). One repetition maximum tests (1RM) were assessed on flat bench-press (BP), lat-pull down (LPD), leg-curl (LC), knee extension (KE), and leg-press 45° (LP45) exercises. Linear regression modelled the relationships of BMD and BMC to the regional body composition and 1RM values. Measurements of dispersion and error (R²_adj and standard error of estimate (SEE)) were tested, setting ρ at ≤0.05. The BMD mean value for whole-body was 1.12±0.09 g/cm² and BMC attained 2477.9 ± 379.2 g. The regional lean mass (LM) in upper-limbs (UL) (= 6.80±1.21 kg) was related to BMC and BMD for UL (R²_adj = 0.74, p<0.01, SEE = 31.0 g and R²_adj = 0.63, SEE = 0.08 g/cm²), and LM in lower-limbs (LL) (= 19.13±2.50 kg) related to BMC and BMD for LL (R²_adj = 0.68, p<0,01, SEE = 99.3 g and R²_adj = 0.50, SEE = 0.20 g/cm²). The 1RM in BP was related to BMD (R²_adj = 0.51, SEE = 0.09 g/cm²), which was the strongest relationship among values of 1RM for men; but, 1RM on LPD was related to BMC (R²_adj = 0.47, p<0.01, SEE = 44.6 g), and LC was related to both BMC (R²_adj = 0.36, p<0.01, SEE = 142.0 g) and BMD (R²_adj = 0.29, p<0.01, SEE = 0.23 g/cm²). Hence, 1RM for multi-joint exercises is relevant to BMC and BMD in young men, strengthening the relationship between force and LM, and suggesting both to parametrizes bone mineral health.

Lower serum P1NP/βCTX ratio and hypoalbuminemia are independently associated with osteoporotic nonvertebral fractures in older adults

Purpose

To estimate the discriminative value of serum P1NP/βCTX ratio and albumin levels in hospitalized orthogeriatric patients with and without nonvertebral fractures.

Methods

In 1,239 orthogeriatric patients (mean age 78.1±9.52 years, 69.1% women) including 854 (68.9%) with osteoporotic nonvertebral fractures (455 [36.7%] with hip fracture [HF]) and 385 (31.1%) without fractures, markers of bone formation (procollagen type 1 N-terminal propeptide [P1NP], osteocalcin [OC], and bone resorption (beta-C-terminal cross-linking telopeptide of type 1 collagen [βCTX]), indices of mineral metabolism, and parameters of liver and renal functions were assessed; data on clinical and laboratory characteristics were collected prospectively.

Results

Both lower serum P1NP/βCTX ratio and albumin concentration (as continuous or categorical variables) were independently associated with fracture presence in multivariate logistic regressions. Compared with the highest P1NP/βCTX tertile, the prevalence of HF, after adjustment for multiple covariates, was 3-fold higher in the lowest tertile and 1.5 times higher in the middle tertile; presence of any fracture was 2.3- and 1.6-fold higher, respectively; patients with albumin levels in the lowest tertile had multivariate odds ratio (OR) of 4.6 for HF and 2.8 for any fracture, in the middle tertile the ORs were 2.2 and 1.3, respectively. The P1NP/βCTX <100.0 (median) and hypoalbuminemia (<33 g/L) demonstrated area under the curve values for HF of 0.802 and 0.806, respectively, and for any fractures of 0.711 and 0.706, respectively. When both characteristics were combined, the ORs for HF or any fracture, compared with the nonfractured group, were 7.8 and 3.2, respectively, with an accuracy of 79.6% and 71.6%, respectively.

Conclusions

In orthogeriatric patients, both serum P1NP/βCTX ratio and albumin levels demonstrated an inverse dose–effect relationship with the prevalence of nonvertebral fractures and independently indicated fracture presence with acceptable discriminatory power. Lower P1NP/βCTX (<100) and hypoalbuminemia could be useful simple additive prognostic tools for fracture risk stratification in the elderly.

Proximal Femur Volumetric Bone Mineral Density and Mortality: 13 Years of Follow-Up of the AGES-Reykjavik Study

Bone mineral density (BMD) has been linked to mortality, but little is known about the independent contribution of each endosteal bone compartment and also the rate of bone loss to risk of mortality. We examined the relationships between (1) baseline trabecular and cortical volumetric BMD (vBMD) at the proximal femur, and (2) the rate of trabecular and cortical bone loss and all-cause mortality in older adults from the AGES-Reykjavik study. The analysis of trabecular and cortical vBMD and mortality was based on the baseline cohort of 4654 participants (aged ≥66 years) with a median follow-up of 9.4 years; the association between rate of bone loss and mortality was based on 2653 participants with bone loss data (median follow-up of 5.6 years). Analyses employed multivariable Cox-proportional models to estimate hazard ratios (HRs) with time-varying fracture status; trabecular and cortical variables were included together in all models. Adjusted for important confounders, Cox models showed that participants in the lowest quartile of trabecular vBMD had an increased risk of mortality compared to participants in other quartiles (HR = 1.12; 95% confidence interval (CI), 1.01 to 1.25); baseline cortical vBMD was not related to mortality (HR = 1.08; 95% CI, 0.97 to 1.20). After adjustment for time-dependent fracture status, results were attenuated and not statistically significant. A faster loss (quartile 1 versus quartiles 2-4) in both trabecular and cortical bone was associated with higher mortality risk (HR = 1.37 and 1.33, respectively); these associations were independent of major potential confounders including time-dependent incident fractures (HR = 1.32 and 1.34, respectively). Overall, data suggest that faster bone losses over time in both the trabecular and cortical bone compartments are associated with mortality risk and that measurements of change in bone health may be more informative than single-point measurements in explaining mortality differences in older adults. © 2017 American Society for Bone and Mineral Research.

Associations of 24-hour sleep duration and CT-derived measurements of muscle and bone: The AGES-Reykjavik Study

BACKGROUND

Although the importance of sleep on preservation of several physiological functions is well known, the relationship with the two interconnected tissues - muscle and bone is less understood.

OBJECTIVES

This study aimed to examine the association of 24-hour sleep duration with mid-thigh muscle composition and proximal femur volumetric bone mineral density (vBMD).

METHODS

2438 men and 3326 women aged 66 to 96years, residents in the Reykjavik area, were included in this cross-sectional study. Proximal femur integral vBMD, mid-thigh muscle area and muscle attenuation were assessed with computed tomography. Sleep and nap habits were assessed using a questionnaire.

RESULTS

We found that after adjustment for age and BMI long sleep duration (>8h/d) was negatively associated with thigh lean area in both men (B=-2.21, 95% confidence interval (CI): -4.01, -0.40) and women (B=-2.39, 95% CI: -3.75, -1.03) and with muscle attenuation (B=-0.95, 95% CI: -1.47, -0.43) only in women. After adjustments for age, health and lifestyle factors the association between long sleep duration and muscle lean area was attenuated and became nonsignificant while associations with muscle attenuation remained marginally significant (B=-0.51, 95% CI: -1.03, -0.002). Sleep duration was not associated with proximal femur integral vBMD in the multivariate models.

CONCLUSION

Long sleep duration, particularly in old women, can affect thigh muscle attenuation (increase in intramuscular fat). Whether optimization of sleep can ameliorate age-associated intramuscular or intermuscular adipose tissue warrants further studies.

Site-Specific Onset of Low Bone Density and Correlation of Bone Turnover Markers in Exclusive Breastfeeding Mothers

PURPOSE

Lactation often affects calcium metabolism and induces bone loss. Calcium supplementation and a high calcium diet are recommended to prevent bone loss, especially during inadequate calcium intake. Our study aimed at determining bone loss in breastfeeding mothers, and if it occurred, whether it was site specific and there were correlations between serum bone turnover markers.

MATERIALS AND METHODS

Since the 6-month exclusive breastfeeding is usually recommended in several countries, our study examined bone mineral density (BMD) in early (1-2 month), mid (3-4 month)-, and late (5-6 month) lactation compared with nonpregnant, nonlactating control women. Site-specific bone loss was monitored in lumbar vertebrae and femora. Bone turnover markers, that is, C-terminal telopeptide of type 1 collagen and N-terminal propeptide of type 1 collagen (P1NP), were determined by electrochemiluminescence immunoassays.

RESULTS

The onset of bone loss in exclusive breastfeeding mothers was site specific, for example, in the lumbar bone at mid-lactation and in the femoral bone in late lactation. Serum ionized calcium levels in late lactation were lower than the normal levels. In addition, a correlation was found between bone turnover marker, P1NP, and femoral BMD.

CONCLUSIONS

The onset of bone loss in exclusive breastfeeding mothers was site specific, and the lumbar bone was a vulnerable and perhaps better representative site for bone loss detection. It was suggested that the optimal starting time for calcium supplementation should be before the mid-lactation when the bone loss was observed. In addition, the biochemical marker that best predicted the onset of bone loss in lactating women was P1NP.

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.