Clinical usefulness of bone turnover marker concentrations in osteoporosis

Preventive machine learning models incorporating health checkup data and hair mineral analysis for low bone mass identification

Machine learning (ML) models have been increasingly employed to predict osteoporosis. However, the incorporation of hair minerals into ML models remains unexplored. This study aimed to develop ML models for predicting low bone mass (LBM) using health checkup data and hair mineral analysis. A total of 1206 postmenopausal women and 820 men aged 50 years or older at a health promotion center were included in this study. LBM was defined as a T-score below - 1 at the lumbar, femur neck, or total hip area. The proportion of individuals with LBM was 59.4% (n = 1205). The features used in the models comprised 50 health checkup items and 22 hair minerals. The ML algorithms employed were Extreme Gradient Boosting (XGB), Random Forest (RF), Gradient Boosting (GB), and Adaptive Boosting (AdaBoost). The subjects were divided into training and test datasets with an 80:20 ratio. The area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and an F1 score were evaluated to measure the performances of the models. Through 50 repetitions, the mean (standard deviation) AUROC for LBM was 0.744 (± 0.021) for XGB, the highest among the models, followed by 0.737 (± 0.023) for AdaBoost, and 0.733 (± 0.023) for GB, and 0.732 (± 0.021) for RF. The XGB model had an accuracy of 68.7%, sensitivity of 80.7%, specificity of 51.1%, PPV of 70.9%, NPV of 64.3%, and an F1 score of 0.754. However, these performance metrics did not demonstrate notable differences among the models. The XGB model identified sulfur, sodium, mercury, copper, magnesium, arsenic, and phosphate as crucial hair mineral features. The study findings emphasize the significance of employing ML algorithms for predicting LBM. Integrating health checkup data and hair mineral analysis into these models may provide valuable insights into identifying individuals at risk of LBM.

Evaluation of Biomarkers of Bone Metabolism on Salivary Matrix in the Remodeling of Periodontal Tissue during Orthodontic Treatment

The aim of this study was to evaluate changes in the concentration of N-terminal type I collagen extension pro-peptide (PINP), tartrate-resistant acid phosphatase (TRAcP), and parathyroid hormone-related protein (PTHrP) in saliva during orthodontic treatment in order to evaluate whether changes in bone turnover marker (BTM) concentration can help highlight the effects of orthodontic mechanical loading in the absence of clinical evidence of tooth movement in terms of tooth movement. Saliva samples from 25 apparently healthy young subjects (10 females and 15 males) were collected using Salivette® (Sarstedt) with cotton swabs and the concentrations of PTHrP, TRAcP 5b, and PINP were analyzed at time 0 (T1), 25 days (T2), and at 45 days (T3). Differences in the median value of biomarker levels between baseline T1 and follow-up of the different groups (T2 and T3) were assessed using the non-parametric Mann-Whitney U test. Trough concentrations of P1NP, PTHrP, and TRAcP were 0.80 µg/L, 0.21 ng/mL, and 0.90 U/L above the method LOD. The non-parametric Mann-Whitney U test confirmed a statistically significant difference in T1 versus concentrations of T2 and T3. All subjects evaluated had a statistically significant difference between T1 vs. T3. when compared with the specific critical difference (RCV) for the analyte The results obtained demonstrate that the evaluation of BTM changes in saliva can help the evaluation of orthodontic procedures and the monitoring of biomechanical therapy.

How to Suppress Mineral Loss and Stimulate Anabolism in Postmenopausal Bones with Appropriate Timing of Exercise and Nutrients

Background. Bone Health and Osteoporosis Foundation (BHOF) reports that as of 2023, approximately 10 million of older Americans have osteoporosis and another 44 million have low bone density. Osteoporosis is a serious handicap for the elderly and, in particular, for estrogen-deficient postmenopausal women, as it increases the risk of debilitating bone weakness and fractures. The BHOF recommendations for prevention of osteopenia, osteoporosis and bone fractures are to perform weight-bearing and muscle-strengthening exercises and to take recommended amounts of daily calcium and vitamin D. Methods. The purpose of this review is to describe and discuss recent evidence-based research on how to effectively utilize timing of exercise and calorie intake for stimulation of postmenopausal bone anabolism, and to provide this new information in the form of specific and actionable recommendations. Results. The five evidence-based recommendations are as follows: 1. Select an appropriate circadian time of day for exercise; 2. Increase walking speed to raise the movement momentum; 3. Eat a weight-maintenance meal one or two hours before the exercise bout; 4. Sustain the duration of walking activity (impulse) for 40 to 45 min; and 5. Repeat effective exercise stimulus 7 to 8 h after the first one to double the anabolic effect. Osteogenesis can also be increased with subthreshold mechanical loading, where needed, under several special circumstances. Conclusions. This review should provide pragmatic actionable pointers on how to utilize the idiosyncratic bone responsiveness to timing of movement and meals to prevent osteoporosis and encourage research toward a better understanding of how bone detects adequacy of a mechanical stimulus and determines duration of necessary rest to recover its sensitivity to mechanical stimulation and nutrients.

Clinical use of bone markers: a challenge to variability

Bone markers are a group of substances released into circulation during bone formation and/or resorption. These substances can be measured in blood and urine to obtain information about metabolic bone disorders. This review provides an insight into factors influencing bone marker variability and describes different approaches to minimize variability and interpret results appropriately. Variability in bone marker concentrations results from biological and analytical variability across assays. Other influencing factors include gender, age, physical exercise, circadian rhythm, and diet. The multiplicity of influencing factors hinders the establishment of accurate reference values. Gaining a deep understanding of bone marker variability is the first step to ascertain their clinical usefulness. Bone marker variability can be minimized by controlling as many variables as it is possible and through the standardization of patient preparation and sample collection and handling.

Utilidad clínica de los biomarcadores óseos: un desafío a la variabilidad

Los biomarcadores óseos son un conjunto de sustancias que son liberadas a la circulación sanguínea durante el proceso de formación y/o resorción ósea y que podemos medir en sangre y orina para obtener información sobre los trastornos metabólicos del hueso. La revisión traza una perspectiva sobre los factores que influyen en la variabilidad de los biomarcadores óseos y describe los aspectos a considerar para reducirla al máximo e interpretar los resultados de manera adecuada. La variabilidad que podemos observar en la concentración de los biomarcadores óseos engloba diversos aspectos que abarcan desde su variabilidad biológica y la variabilidad de los ensayos empleados en su medida hasta la variabilidad derivada de la influencia de numerosos factores, entre los cuales el sexo, la edad, el ejercicio, su ritmo circadiano o la dieta. Todo ello se refleja en la dificultad de establecer valores de referencia precisos. El conocimiento de esta variabilidad es el primer desafío que debe afrontar su empleo en la práctica clínica. Es necesario minimizar la variabilidad de los biomarcadores óseos controlando el máximo de variables que sea posible, así como estandarizando la preparación del paciente antes de la toma de las muestras, así como su obtención y manejo.

The Use of Bone-Turnover Markers in Asia-Pacific Populations

Bone-turnover marker (BTM) measurements in the blood or urine reflect the bone-remodeling rate and may be useful for studying and clinically managing metabolic bone diseases. Substantial evidence supporting the diagnostic use of BTMs has accumulated in recent years, together with the publication of several guidelines. Most clinical trials and observational and reference-interval studies have been performed in the Northern Hemisphere and have mainly involved Caucasian populations. This review focuses on the available data for populations from the Asia-Pacific region and offers guidance for using BTMs as diagnostic biomarkers in these populations. The procollagen I N-terminal propeptide and β-isomerized C-terminal telopeptide of type-I collagen (measured in plasma) are reference BTMs used for investigating osteoporosis in clinical settings. Premenopausal reference intervals (established for use with Asia-Pacific populations) and reference change values and treatment targets (used to monitor osteoporosis treatment) help guide the management of osteoporosis. Measuring BTMs that are not affected by renal failure, such as the bone-specific isoenzyme alkaline phosphatase and tartrate-resistant acid phosphatase 5b, may be advantageous for patients with advanced chronic kidney disease. Further studies of the use of BTMs in individuals with metabolic bone disease, coupled with the harmonization of commercial assays to provide equivalent results, will further enhance their clinical applications.

A protocol for the prospective study of urinary cadmium with risk of fracture, bone loss, and muscle loss

Cadmium (Cd) is a heavy metal and natural element found in soil and crops with increasing concentrations linked to phosphate fertilizers and sewage sludge applied to crop lands. A large fraction of older US men and woman have documented Cd exposure. Cd exposure has proven health concerns such as risk of lung cancer from inhalation and impaired renal function; however, growing evidence suggests it also influences bone and muscle health. Given that low levels of Cd could affect bone and muscle, we have designed prospective studies using the two largest and most detailed US studies of bone health in older men and women: the Osteoporotic Fractures in Men Study and the Study of Osteoporotic Fractures. We are investigating the association of urinary cadmium (U-Cd), as a surrogate for long-term Cd exposure, with bone and muscle health. Building off suggestive evidence from mechanistic and cross-sectional studies, this will be the first well-powered prospective study of incident fracture outcomes, bone loss, and muscle loss in relation to U-Cd, an established biomarker of long-term Cd exposure. The following is a proposed protocol for the intended study; if successful, the proposed studies could be influential in directing future US policy to decrease Cd exposure in the US population similar to recent policies adopted by the European Union to limit Cd in fertilizers.

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.

Effects of Bazedoxifene/Vitamin D Combination Therapy on Serum Vitamin D Levels and Bone Turnover Markers in Postmenopausal Women with Osteopenia: A Randomized Controlled Trial

BACKGROUND

This study aimed to evaluate the effectiveness of bazedoxifene/vitamin D combination therapy in preventing osteoporosis in postmenopausal women with osteopenia.

METHODS

This was an open-label, multicenter randomized-controlled, phase 4 clinical trial. Women between ages of 55 and 70 years in 9 medical tertiary centers in Korea were enrolled and assigned into 2 groups: an experiment group and a control group. The experimental group received bazedoxifene 20 mg/vitamin D 800 IU tablets for 6 months, and the control group received calcium 100 mg/vitamin D 1,000 IU tablets for 6 months.

RESULTS

A total of 142 patients (70 in the experimental group and 72 in the control group) were included. The least-square mean±standard error of change in propeptide of type I collagen after 3 months was -6.87±2.56% in the experimental group and 1.22±2.54% in the control group. After 6 months, it was -21.07±2.75% in the experimental group and 1.26±2.71% in the control group. The difference between the 2 groups was -22.33% (p<0.01). The change of C-terminal telopeptide was -12.55±4.05% in the experimental group and 11.02±4.03% in the control group after 3 months. It was -22.0±3.95% and 10.20±3.89, respectively, after 6 months. The difference between the 2 groups was -32.21% (p<0.01) after 6 months. There was no significant difference in adverse events between the 2 groups.

CONCLUSIONS

The osteoporosis preventive effect and safety of administering bazedoxifene/vitamin D combination pill were confirmed in postmenopausal women who needed osteoporosis prevention.

ELISA array-based immunoassay for multiplex detection of osteoporosis-relevant biomarkers

Aim: This study aimed to develop an ELISA array-based immunoassay for the simultaneous detection of osteoporosis-relevant biomarkers. Methods: ELISA array was constructed and its performance was evaluated using commercial antigens. The validity was further confirmed using traditional ELISA. Results: The constructed ELISA array showed good repeatability. The linear ranges and limits of detection for the four markers mentioned above were 0.01-8 ng/ml (1 pg/ml), 5.0-1000 ng/ml (1 ng/ml), 0.5-400 ng/ml (0.1 ng/ml) and 1-100 ng/ml (1 ng/ml), respectively. The measured concentrations of serum samples by ELISA array showed high correlation with those from traditional ELISA. Conclusion: ELISA array-based immunoassay provided a feasible and productive method to multiplex measure markers for osteoporosis.

Measuring levels of hormones in osteoporosis Iraqi women patients

This study was conducted to investigate the effect of the hormone progesterone and testosterone on osteoporosis in women, and it was found that there are statistically significant differences between the hormone progesterone and there are no statistically significant differences for the hormone testosterone. The ELISA method measured the testosterone concentration in the blood and the progesterone concentration. The purpose of the study measuring the levels of some hormones in osteoporosis Iraqi women patients. Fifty (50) women patients with osteoporosis were admitting Baghdad Teaching Hospital with osteoporosis and 40 healthy populations, and it was conducted in Baghdad Teaching Hospital/ Bone density examination unit/ in Baghdad-Iraq. Endocrine testing Estrogen content was measured following the manufacturer's instructions using available human Uno ELISA kits (Immunolab GmbH, Kassel, Germany). Results showed a significant difference (P-value of 0.0038) in progesterone between the two study groups. The mean of patient groups was mean±SD (6.759 ± 6.705), and control groups were mean±SD (11.03 ± 6.546). The main risk factor for osteoporosis is the presence of more progesterone when comparing patients with healthy women. As for testosterone, there are no significant differences; that is, it does not affect women Keywords: ELISA Technique, progesterone, testosterone

Changes in Bone Metabolism in Patients with Rheumatoid Arthritis during Tumor Necrosis Factor Inhibitor Therapy

Tumor necrosis factor alpha (TNF-α), which enhances osteoclast activity and bone resorption, is one of the key inflammation mediators in rheumatoid arthritis (RA). The aim of this study was to assess the influence of yearlong TNF-α inhibitor application on bone metabolism. The study sample comprised 50 female patients with RA. Analyses involved the osteodensitometry measurements obtained using a "Lunar" type apparatus and the following biochemical markers from serum: procollagen type 1 N-terminal propeptide (P1NP), beta crosslaps C-terminal telopeptide of collagen type I (b-CTX) by ECLIA method, total and ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone and vitamin D. Analyses revealed changes in bone mineral density (BMD) at L1-L4 and the femoral neck, with the difference in mean BMD (g/cm²) not exceeding the threshold of statistical significance (p = 0.180; p = 0.502). Upon completion of 12-month therapy, a significant increase (p < 0.001) in P1NP was observed relative to b-CTX, with mean total calcium and phosphorus values following a decreasing trend, while vitamin D levels increased. These results suggest that yearlong application of TNF inhibitors has the capacity to positively impact bone metabolism, as indicated by an increase in bone-forming markers and relatively stable BMD (g/cm²).

Practical Considerations for the Clinical Application of Bone Turnover Markers in Osteoporosis

Bone turnover markers (BTMs) are released during the bone remodelling cycle and are measurable in blood or urine, reflecting bone remodelling rate. They have been useful in elucidating the pharmacodynamics and effectiveness of osteoporosis medication in clinical trials and are increasingly used in routine clinical management of osteoporosis, especially for monitoring therapy, in addition to their use in other metabolic bone disease such as Paget's disease of bone and osteomalacia. Serum β isomerised C-terminal telopeptide of type I collagen and pro-collagen I N-terminal propeptide have been designated as reference BTMs for use in osteoporosis. In addition, bone-specific isoenzyme of alkaline phosphatase (B-ALP) secreted by osteoblasts and tartrate-resistant acid phosphatase 5b (TRACP-5b) secreted by osteoclasts are also found to be specific markers of bone formation and resorption, respectively. The concentrations of the latter enzymes in blood measured by immunoassay provide reliable measures of bone turnover even in the presence of renal failure. B-ALP is recommended for use in the assessment of renal bone disease of chronic kidney disease, and TRACP-5b shows promise as a marker of bone resorption in that condition. BTMs in blood do not suffer from biological variation to the same extent as the older BTMs that were measured in urine. Appropriate patient preparation and sample handling are important in obtaining accurate measures of BTMs for clinical use. Reference change values and treatment targets have been determined for the reference BTMs for their use in monitoring osteoporosis treatment. Further ongoing studies will enhance their clinical applications.

Determination of parathyroid hormone: from radioimmunoassay to LCMS/MS

Parathyroid hormone (PTH) determination is of paramount importance for the exploration of diseases related with calcium metabolism and for the follow-up of patients suffering from bone and mineral disorders associated with chronic kidney diseases (CKD-MBD). Unfortunately, the biologically active form of PTH, i.e. 1-84 PTH, circulates in the blood stream with many fragments and post-translationally modified forms, which decreases the specificity of immunoassays. The assays used to measure PTH, either from 2nd or 3rd generation, are not standardised, which may lead to interpretation errors and clinical consequences. Reference ranges for PTH have neither been always correctly established and the stability of the peptide is also a matter of concern. Fortunately, these last years, newer techniques using mass spectrometry (either high resolution or triple quadripole) coupled with liquid chromatography have been developed, which will help to standardise the different assays. Indeed, PTH assays standardisation is one of the task of the IFCC Committee for Bone Metabolism. Such standardisation will allow a better consistency in the interpretation of the results and will promote studies aiming at the establishment of correct reference ranges.

Intra-Individual Changes in Total Procollagen-Type 1 N-terminal Propeptide in a Korean Adult Population

We aimed to investigate intra-individual changes in total procollagen-type 1 N-terminal pro-peptide (P1NP), a biochemical marker of bone turnover, to understand patient populations and test utilization in a Korean adult population while considering different definitions of least significant changes by sex, age, and medical institution type. Overall, 31,501 P1NP tests were performed on 24,644 Korean adults (3389 men and 21,255 women) with a median age of 68.9 years (interquartile range, IQR, 61.2–77.2) for osteoporosis evaluation. Among these, 1331 (5.4%) patients (127 men and 1204 women) underwent ≥3 follow-up P1NP measurements. The median follow-up period was 12.5 months (IQR, 11.7–15.9). Among 1331 patients, 64.4% experienced a decrease in P1NP and 35.6% experienced an increase in P1NP during follow-up. Among these, the proportion of patients who experienced serum P1NP changes ≥14.4% from baseline was 92.3%, and the proportion of patients who achieved ≤40 ng/mL (a median level of premenopausal Korean women) during follow-up was 31.8%. The overall proportion of patients that experienced a serum P1NP change exceeding the least significant change during follow-up was not significantly different by the type of medical institution.

Current use of bone turnover markers in the management of osteoporosis

The adult bone is continuously being remodelled to repair microdamage, preserve bone strength and mechanical competence as well as maintain calcium homeostasis. Bone turnover markers are products of osteoblasts (bone formation markers) and osteoclasts (bone resorption markers) providing a dynamic assessment of remodelling (turnover). Resorption-specific bone turnover markers are typically degradation products of bone collagen molecules (N- [NTX] and C-telopeptide cross-linked type 1 collagen [CTX]), which are released into the circulation and excreted in urine; or enzymatic activities reflecting osteoclastic resorption, tartrate-resistant acid phosphatase [TRACP]. Formation-specific bone turnover markers embrace different osteoblastic activities: type 1 collagen synthesis (Procollagen type I N- propeptide [PINP]), osteoblast enzymes (bone-specific alkaline phosphatase [BALP]), or bone matrix proteins [osteocalcin]. Among individuals not receiving osteoporosis treatment, resorption and formation markers are tightly linked and highly correlated (r= 0.6-0.8). Significant biological variability was reported in the past, but these issues have been greatly improved with automated assays and attention to pre-analytical and analytical factors that are known to influence bone turnover marker levels. Bone turnover markers are not useful in the diagnosis of osteoporosis, the individual prediction of bone loss, fracture, or rare complications, or in the selection of pharmacological treatment. Despite remaining issues with reference intervals and assays harmonization, bone turnover markers have proven to be useful in elucidating the pharmacodynamics and effectiveness of osteoporosis medications in clinical trials. As an alternative to BMD testing, BTMs may be useful to monitor osteoporosis therapies.

Prevention and Treatment of Glucocorticoid-Induced Osteoporosis in Adults: Consensus Recommendations From the Belgian Bone Club

Glucocorticoids are effective immunomodulatory drugs used for many inflammatory disorders as well as in transplant recipients. However, both iatrogenic and endogenous glucocorticoid excess are also associated with several side effects including an increased risk of osteoporosis and fractures. Glucocorticoid-induced osteoporosis (GIOP) is a common secondary cause of osteoporosis in adults. Despite availability of clear evidence and international guidelines for the prevention of GIOP, a large treatment gap remains. In this narrative review, the Belgian Bone Club (BBC) updates its 2006 consensus recommendations for the prevention and treatment of GIOP in adults. The pathophysiology of GIOP is multifactorial. The BBC strongly advises non-pharmacological measures including physical exercise, smoking cessation and avoidance of alcohol abuse in all adults at risk for osteoporosis. Glucocorticoids are associated with impaired intestinal calcium absorption; the BBC therefore strongly recommend sufficient calcium intake and avoidance of vitamin D deficiency. We recommend assessment of fracture risk, taking age, sex, menopausal status, prior fractures, glucocorticoid dose, other clinical risk factors and bone mineral density into account. Placebo-controlled randomized controlled trials have demonstrated the efficacy of alendronate, risedronate, zoledronate, denosumab and teriparatide in GIOP. We suggest monitoring by dual-energy X-ray absorptiometry (DXA) and vertebral fracture identification one year after glucocorticoid initiation. The trabecular bone score might be considered during DXA monitoring. Extended femur scans might be considered at the time of DXA imaging in glucocorticoid users on long-term (≥ 3 years) antiresorptive therapy. Bone turnover markers may be considered for monitoring treatment with anti-resorptive or osteoanabolic drugs in GIOP. Although the pathophysiology of solid organ and hematopoietic stem cell transplantation-induced osteoporosis extends beyond GIOP alone, the BBC recommends similar evaluation, prevention, treatment and follow-up principles in these patients. Efforts to close the treatment gap in GIOP and implement available effective fracture prevention strategies into clinical practice in primary, secondary and tertiary care are urgently needed.

Circadian rhythm of markers of bone turnover in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have a high risk of bone fractures. A circadian rhythmicity in turnover and mineralization of bone appears to be of importance for bone health. In CKD disturbances in the circadian rhythm of various functions has been demonstrated and indeed the circadian rhythm in the mineral metabolism is disturbed. The aim of the present study was to compare the circadian rhythm of bone turnover markers in ten patients with CKD to ten healthy controls. Bone turnover markers (C-terminal telopeptide of type I collagen, tartrate-resistant acid phosphatase 5b, N-terminal propeptide of type I procollagen, bone alkaline phosphatase and osteocalcin) were measured every third hour for 24 h. All bone turnover markers displayed a significant circadian rhythm in both groups and there were no significant differences in the rhythmicity between the two groups (no group*time interaction). As expected, due to the reduced renal clearance, the overall level of C-terminal telopeptide of type I collagen and osteocalcin was higher in CKD compared to the healthy controls. The present study suggests that disturbances in the circadian rhythm of bone turnover do not explain the metabolic bone disease and increased risk of fractures in CKD.

Evaluating Patients for Secondary Causes of Osteoporosis

PURPOSE OF REVIEW

This review provides suggestions for the evaluation of patients with osteoporosis in order to assure that the diagnosis is correct, to identify potentially correctable conditions contributing to skeletal fragility and fracture risk, and to assist in individualizing management decisions.

RECENT FINDINGS

Some patients who appear to have osteoporosis have another skeletal disease, such as osteomalacia, that requires further evaluation and treatment that is different than for osteoporosis. Many patients with osteoporosis have contributing factors (e.g., vitamin D deficiency, high fall risk) that should be addressed before and after starting treatment to assure that treatment is effective and safe. Evaluation includes a focused medical history, skeletal-related physical examination, assessment of falls risk, appropriate laboratory tests, and rarely transiliac double-tetracycline labeled bone biopsy. Evaluation of patients with osteoporosis before starting treatment is essential for optimizing clinical outcomes.

Fluctuation of bone turnover markers' levels in samples of gingival crevicular fluid after orthodontic stimulus: a systematic review

BACKGROUND

The aim of the present study was to provide an overview of gingival crevicular fluid (GCF) bone turnover markers (BTMs) concerning the physiology of orthodontic tooth movement (OTM) and assess their potential contributions to regulating bone remodeling, that could prove useful in designing future approaches to modulating orthodontic tooth movement.

METHODS

Multiple electronic databases (MEDLINE/PubMed, Ovid MEDLINE, Ovid Embase, LILACS, and Cochrane Library) were searched up to October 1st, 2020. Randomized controlled trials (RCTs), controlled clinical trials, observational studies of prospective and retrospective designs, and cross-sectional studies reporting on levels of BTMs in GCF were eligible for inclusion. The quality of the included RCTs was assessed per the revised Cochrane risk of bias tool for randomized trials (RoB 2.0), whereas the risk of bias of the included cohort studies was assessed using the Risk Of Bias In Non-randomized Studies of Interventions tool.

RESULTS

Five RCTs, 9 prospective cohort studies, and 1 cross-sectional study fulfilled the inclusion criteria. The risk of bias was deemed as high for the RCTs and 4 of the prospective studies and moderate for the rest of the studies. The following biomarkers for bone formation were assessed: bone alcaline phosphatase (BALP), alcaline phosphatase (ALP), and osteocalcin (OC). For bone resorption, the following BTMs were assessed: deoxypyridinoline (DPD) and pyridinoline (PYD), N-terminal telopeptide (NTX), osteopontin (OPN), and tartrate-resistant acid phosphatase (TRAP). The follow-up period ranged mainly from baseline to 45 days, although one study had an expanded follow-up period of up to 16 months. The results of the included studies comparing different BTMs were heterogeneous and qualitatively reported.

CONCLUSIONS

Current evidence continues to support the potential for BTMs to provide clinically useful information particularly for adjusting or standardizing the orthodontic stimulus. The present systematic review has retrieved studies of high, overall, risk of bias, and has unveiled a substantial clinical and methodological heterogeneity among included studies. Further data of the relationships between the clinical assays and the physiological or pre-analytical factors contributing to variability in BTMs' concentrations are required.

SYSTEMATIC REVIEW REGISTRATION

CRD42020212056 .

Analytical evaluation of the Nittobo Medical tartrate resistant acid phosphatase isoform 5b (TRACP-5b) EIA and comparison with IDS iSYS in different clinically defined populations

OBJECTIVES

Tartrate-resistant acid phosphatase, isoform 5b (TRACP-5b) is a bone resorption marker not influenced by renal function or food intake. TRACP-5b can be measured with Nittobo Medical enzymatic-immunoassay and IDS-iSYS automated immunoassay. We evaluated the Nittobo assay and established reference ranges for a Western-European population. We compared Nittobo and IDS results in different well-defined clinical populations.

METHODS

We established the limits of detection and quantification (LOD-LOQ), linearity, imprecision and the reference ranges in 119 males, 50 women (<45 years) and 120 women (>60 years) for TRACP-5b with the Nittobo assay. We compared both assays in 30 hemodialyzed (HD), and 40 stage 3-5 patients suffering from chronic kidney disease (CKD), 40 patients suffering from rheumatoid arthritis and osteoporosis and 80 post-menopausal women. We measured TRACP-5b, β-crosslaps (β-CTX), bone alkaline phosphatase (B-ALP) and PTH in 20 hemodialyzed (HD) and 40 CKD patients.

RESULTS

LOD and LOQ were 0.02 and 0.35 U/L. CV ranged from 8.3 to 4.3% (2/5 samples presenting CV > desirable CV). Method was linear up to of 11.3 U/L. Upper and lower limits of normality were 0.8-7.6 U/L in men, 0.9-4.7 U/L in women <45 and 0.9-7.1 U/L in women >60. The regression equation between the 2 methods was Nittobo = 1.13 (95% CI: 1.09-1.16) × iSYS - 0.4 (95% CI: -0.5; -0.3). TRACP-5b and b-ALP were in their respective reference ranges for most of CKD and HD patients. That was not the case for β-CTX, which increased with decreasing eGFR.

CONCLUSIONS

Nittobo TRACP-5b presents interesting analytical features and a good concordance with IDS iSYS. These methods could thus potentially be harmonized.

A comparison of changes in bone turnover markers after gastric bypass and sleeve gastrectomy, and their association with markers of interest

BACKGROUND

It is still debated whether differences in bone turnover markers (BTMs) exist between the 2 most popular bariatric surgery procedures (Roux-en-Y gastric bypass [RYGB] and sleeve gastrectomy [SG]).

OBJECTIVES

To compare changes in BTMs after RYGB and SG, and to investigate their association with predefined markers of interest.

SETTING

University hospital, Lille, France.

METHODS

An ancillary investigation of a prospective cohort was conducted. SG patients with severe obesity ≥40 years were matched one-to-one to RYGB patients for age, sex, body mass index (BMI), and menopausal status. BTMs, as well as predefined markers of interest, were measured at baseline, 12, and 24 months after bariatric surgery.

RESULTS

Sixty-four patients (66% women) had a mean (standard deviation [SD]) age of 49.6 years (5.1) and a mean (SD) BMI of 45.0 kg/m² (6.0). From baseline to 12 months, a significant increase in BTMs was observed in both groups (P < .001). Moreover, RYGB was associated with a greater increase in C-terminal telopeptide (β-CTX) and procollagen type 1 N-terminal propeptide (PINP) compared with SG (P < .0001). From 12 to 24 months, a significant decrease in BTMs was observed in both groups, but no significant differences were found between RYGB and SG. However, BTMs did not return to baseline levels. The changes in PINP and β-CTX at 12 months were independently associated with the type of surgical procedure, after adjusting for weight or each predefined marker of interest (all P < .0001).

CONCLUSION

RYGB was associated with a greater increase in BTMs than SG at 12 and 24 months.

Effect of Vitamin E Supplement on Bone Turnover Markers in Postmenopausal Osteopenic Women: A Double-Blind, Randomized, Placebo-Controlled Trial

Vitamin E is a strong anti-oxidative stress agent that affects the bone remodeling process. This study evaluates the effect of mixed-tocopherol supplements on bone remodeling in postmenopausal osteopenic women. A double-blinded, randomized, placebo-controlled trial study was designed to measure the effect of mixed-tocopherol on the bone turnover marker after 12 weeks of supplementation. All 52 osteopenic postmenopausal women were enrolled and allocated into two groups. The intervention group received mixed-tocopherol 400 IU/day, while the control group received placebo tablets. Fifty-two participants completed 12 weeks of follow-up. Under an intention-to-treat analysis, vitamin E produced a significant difference in the mean bone resorption marker (serum C-terminal telopeptide of type I collagen (CTX)) compared with the placebo group (-0.003 ± 0.09 and 0.121 ± 0.15, respectively (p < 0.001)). In the placebo group, the CTX had increased by 35.3% at 12 weeks of supplementation versus baseline (p < 0.001), while, in the vitamin E group, there was no significant change of bone resorption marker (p < 0.898). In conclusion, vitamin E (mixed-tocopherol) supplementation in postmenopausal osteopenic women may have a preventive effect on bone loss through anti-resorptive activity.

Current Lack of Evidence for an Effect of Physical Activity Intervention Combined with Pharmacological Treatment on Bone Turnover Biomarkers in People with Osteopenia and Osteoporosis: A Systematic Review

The process of bone loss occurs silently and progressively with age, often appearing as osteopenia or osteoporosis or related fractures. Given the rapid raise in disease burden and socio-economic costs of these conditions worldwide, drug therapy combined with physical activity can be a useful strategy and bone biomarkers, can represent a useful evaluation tool to assess their effects. The objective of this systematic review, conducted according to PRISMA statement, was to investigate the effects of physical activity interventions combined with drug treatments on bone biomarkers in people with osteopenia and osteoporosis. Through PubMed, Cochrane, Cinahl, Embase, Trip, a comprehensive literature search was performed. Each study's quality was assessed according to the Cochrane risk-of-bias tool. Out of 582 identified articles, 50 full texts were screened. Only one matched the eligibility criteria. The study, scored as high quality, showed, in both experimental and control groups, an increase of CTX and P1NP bone biomarkers, without statistically significant differences. Based on available evidence, no exhaustive conclusion can be drawn. However, this systematic review critically analyses the literature, highlighting the knowledge gap on combined treatments efficacy assessed by bone biomarkers. Moreover, an outlook is provided for the planning of future studies.

Biological sources of variations of tartrate-resistant acid phosphatase 5b in a healthy Japanese population

BACKGROUND

Tartrate-resistant acid phosphatase 5b (TRACP5b) is a bone resorption marker that is mainly used in clinical management of osteoporosis. For proper interpretations of test results for serum TRACP5b, we explored their biological sources of variation, esp. age-related changes, and associations with other bone-related markers in healthy Japanese adults.

METHODS

During the 2009 East-Southeast Asian multicentre study for determination of reference intervals, 72 major laboratory tests were measured by centralized assays in 3541 well-defined healthy volunteers. The current study included 1980 test results in Japanese subjects for five bone-related markers: TRACP5b, bone alkaline phosphatase, intact parathyroid hormone, calcium and inorganic phosphate. Information on sources of variation, including body mass index, smoking habits and ABO-blood group, were obtained from a health status questionnaire.

RESULTS

Gender-specific profiles of age-related changes were observed for each parameter. Increased values starting from 40 years of age in females were most prominent for TRACP5b, followed by bone alkaline phosphatase and inorganic phosphate. TRACP5b in males decreased with body mass index, bone alkaline phosphatase and TRACP5b were higher in blood type-O subjects, especially in males. TRACPT5b was closely correlated with bone alkaline phosphatase, and moderately correlated with adjusted calcium and inorganic phosphate, especially in females aged ≥45 years. Reference intervals for each analyte were determined parametrically based on gender and age.

CONCLUSIONS

This study elucidated sources of variation of TRACP5b and related bone markers in healthy Japanese subjects and demonstrated a specific age profile for each marker. These results are of relevance for better clinical usage and interpretations of serum levels of bone markers.

Associations between bone turnover markers and bone mineral density in older adults

OBJECTIVE

To examine the associations between bone turnover markers (BTMs) and bone mineral density (BMD) in older adults aged 60-85 years.

METHODS

A total of 1124 men (mean age, 69.1 years) and 1203 women (mean age, 70.7 years) from the National Health and Nutrition Examination Survey 1999-2002 were included in this cross-sectional analysis. Independent variables were serum bone-specific alkaline phosphatase (sBAP) and urinary N-telopeptide (uNTx), which are biomarkers of bone formation and resorption, respectively. Outcome variable was lumbar BMD. The associations of sBAP and uNTx levels with lumbar BMD was examined using multivariable linear regression models.

RESULTS

sBAP was negatively associated with lumbar BMD in each multivariable linear regression model, and this negative association was stable in both men and women men (men: β = -0.0028, 95% CI: -0.0046 to -0.0010; women: β = -0.0039, 95% CI: -0.0054 to -0.0023). On the other hand, uNTx was negatively associated with lumbar BMD after adjustment of relevant covariables (β = -0.0328, 95% CI: -0.0523 to -0.0133). However, in the subgroup analysis stratified by gender, this negative association remained only in older women (β = -0.0491, 95% CI: -0.0751 to -0.0231).

CONCLUSION

Our study suggested that elevated sBAP and uNTX levels correlated with decreased lumbar BMD, especially in older women. This finding indicated that maintaining BTMs at low levels may be beneficial to bone health for older adults.

Bone Metabolism and RANKL/OPG Ratio in Rheumatoid Arthritis Women Treated with TNF-α Inhibitors

The aim of this study was to evaluate the effect of anti-tumor necrosis factor α (anti-TNF-α) therapy in combination with methotrexate on bone remodeling and osteoclastogenesis in female patients with RA. Serum levels of bone turnover markers (i.e., C- and N-terminal propeptides of type I procollagen (PICP and PINP), C- and N-terminal cross-linking telopeptides of type I collagen (CTX-I and NTX-I), and soluble receptor activator of nuclear factor κB ligand (sRANKL) and osteoprotegerin (OPG)) were determined by immunoassay at baseline and 15 months after initiation of treatment. Bone mineral density was measured by dual-energy x-ray absorptiometry. We found a significant decrease in serum PINP levels, a biomarker of bone formation, and higher levels of CTX-I and sRANKL indicative of increased bone resorption in RA patients prior to TNFαI treatment compared to the controls. Anti-TNF-α therapy was effective in improving bone metabolism in RA patients as reflected in a decrease in CTX-I (at least partially due to the RANKL/OPG reduction) and a concomitant increase in PINP levels. The bone metabolism changes were independent of the type of TNFαI used. PINP and CTX-I were found to be useful markers of bone metabolism, which may prove the effectiveness of TNF-α therapy earlier than the bone density assessment.

The Indian Society for Bone and Mineral Research (ISBMR) position statement for the diagnosis and treatment of osteoporosis in adults

The Indian Society for Bone and Mineral Research (ISBMR) has herein drafted clinical practice guidelines for the diagnosis and management of osteoporosis for the people of India. Implementation of the position statement in clinical practice is expected to improve the overall care of patients with osteoporosis in India.

PURPOSE

In India, osteoporosis is a major public health problem. However, in the absence of any robust regional guidelines, the screening, treatment, and follow-up of patients with osteoporosis are lagging behind in the country.

METHODS

The Indian Society for Bone and Mineral Research (ISBMR), which is a multidisciplinary group of physicians, researchers, dietitians, and epidemiologists and who study bone and related tissues, in their annual meeting, drafted the guidelines for the diagnosis and management of osteoporosis that would be appropriate in a resource constraint setting like India.

RESULTS

Diagnosis of osteoporosis can be made in a patient with minimal trauma fracture without the aid of any other diagnostic tools. In others, bone mineral density measured by dual-energy X-ray absorptiometry remains the modality of choice. Data indicates that osteoporotic fractures occur at an earlier age in Indians than in the West; hence, screening for osteoporosis should begin at an earlier age. FRAX can be used for fracture risk estimation; however, it may underestimate the risk of future fractures in our population and still needs validation. Maintaining optimum serum 25-hydroxyvitamin D levels is essential, which, in most cases, would require regular vitamin D supplementation. Pharmacotherapy should be guided by the presence/absence of vertebral/hip fractures or the severity of risk based on clinical factors, although bisphosphonates remain the first choice in most cases. Regular follow-up is essential to ensure adherence and response to therapy.

CONCLUSIONS

Implementation of the position statement in clinical practice is expected to improve the overall care of patients with osteoporosis in India.

Assessing bone formation in patients with chronic kidney disease using procollagen type I N-terminal propeptide (PINP): The choice of assay makes a difference

BACKGROUND

Measurement of procollagen type I N-terminal propeptide (PINP) concentration in serum reflects the rate of type I collagen synthesis and can therefore be used as a bone formation marker. There are two methods of PINP quantification; the first measures the trimeric propeptide (intact PINP) and the second measures both the trimeric and monomeric propeptides (total PINP). Trimeric PINP is excreted via hepatic endothelial cells, whereas monomeric PINP is cleared renally. Therefore, in renal failure, the total assay has a positive bias with respect to the intact assay, due to monomeric PINP accumulation. The aim of this study was to compare the performance of both assays across all stages of chronic kidney disease.

METHODS

Serum was taken from male (n = 111) and female (n = 105) patients attending a metabolic bone clinic, and these were partitioned into stages of chronic kidney disease 1-5. Each serum sample was analysed using the Roche electrochemiluminescence immunoassay for total PINP and the Immunodiagnostic Systems chemiluminescence immunoassay for intact PINP.

RESULTS

Passing-Bablok regression analysis comparing both methods showed that with advancing chronic kidney disease there was a proportional positive bias affecting the total assay when compared with the intact assay. This proportional positive bias was statistically significant for chronic kidney disease stages 3b, 4 and 5.

CONCLUSIONS

Based on this method comparison study, usage of the total PINP assay should be avoided in chronic kidney disease stages 3b, 4 and 5 (eGFR ≤44 mL/min/1.73 m²) and instead an intact assay used as the total assay overestimates PINP concentrations due to monomeric PINP accumulation.

Using X-ray diffraction in characterization of bone remodeling and nanocomposites in ovariectomized rats osteopenia model

Sedentary lifestyle and physiological menopause are among the risk factors of osteopenia, especially in elderly people. However, bone mineral density decrease can also be observed in young individuals, for instance, due to deficiency of female sex hormones after surgical interventions, particularly ovariectomy. Our research enabled us to assess the efficacy of whole-body vibration in preventing the loss of bone mineral density in the ovariectomy rat osteopenia model. Thus, whole-body vibration with acceleration level 0.3 g and frequency 50 Hz was used on young female rats, which had been subjected to ovariectomy (n = 18). It had been conducted for 24 weeks, exposure time – 30 minutes per day, 5 times a week. Assessment of mineral component loss of the tibia was performed by means of X-ray diffraction. Bone remodeling was assessed by determining hormones: parathyroid hormone and calcitonin, Ca and P in the blood. X-ray diffraction is an effective method, which enables the evaluation a nanocomposites structure of the bone tissue in the experiment. In the article, we applied this method to determine the loss of bone mineral mass after ovariectomy and the impact of whole-body vibration under such conditions. In the ovariectomy group, the volume of a mineral component significantly decreased starting already from the 16th week (р<0.05) versus control. However, in the group with ovariectomy + whole-body vibration, the loss of a mineral component was insignificant during 8-16 weeks of the investigation, compared with the control group. On the 24th day, the spectrums almost did not differ from ovariectomized rats group. Meanwhile, hormone levels changed in ovariectomized rats group. It should be emphasized that the aforementioned whole-body vibration parameters do not cause severe bone damage or further negative consequences.

A Multicenter Study to Evaluate Harmonization of Assays for C-Terminal Telopeptides of Type I Collagen (ß-CTX): A Report from the IFCC-IOF Committee for Bone Metabolism (C-BM)

BACKGROUND

Biochemical bone turnover markers are useful tools to assess bone remodeling. C-terminal telopeptide of type I collagen (ß-CTX) has been recommended as a reference marker for bone resorption in research studies.

METHODS

We describe the results of a multicenter study for routine clinical laboratory assays for ß-CTX in serum and plasma. Four centers (Athens GR, Copenhagen DK, Liege BE and Sheffield UK) collected serum and plasma (EDTA) samples from 796 patients presenting to osteoporosis clinics. Specimens were analyzed in duplicate with each of the available routine clinical laboratory methods according to the manufacturers' instructions. Passing-Bablok regressions, Bland-Altman plots, V-shape evaluation method, and Concordance correlation coefficient for ß-CTX values between serum and plasma specimens and between methods were used to determine the agreement between results. A generalized linear model was employed to identify possible variables that affected the relationship between the methods. Two pools of serum were finally prepared and sent to the four centers to be measured in 5-plicates on 5 consecutive days with the different methods.

RESULTS

We identified significant variations between methods and between centers although comparison results were generally more consistent in plasma compared to serum. We developed univariate linear regression equations to predict Roche Elecsys®, IDS-iSYS, or IDS ELISA ß-CTX results from any other assay and a multivariable model including the site of analysis, the age, and weight of the patient. The coefficients of determination (R²) increased from approximately 0.80 in the univariate model to approximately 0.90 in the multivariable one, with the site of analysis being the major contributing factor. Results observed on the pools also suggest that long-term storage could explain the difference observed with the different methods on serum.

CONCLUSION

Our results show large within- and between-assay variation for ß-CTX measurement, particularly in serum. Stability of the analyte could be one of the explanations. More studies should be undertaken to overcome this problem. Until harmonization is achieved, we recommend measuring ß-CTX by the same assay on EDTA plasma, especially for research purposes in large pharmacological trials where samples can be stored for long periods before they are assayed.

Validation of a quantitative systems pharmacology model of calcium homeostasis using elagolix Phase 3 clinical trial data in women with endometriosis

Elagolix is a novel, oral gonadotropin‐releasing hormone receptor antagonist indicated for the management of moderate to severe pain associated with endometriosis and heavy menstrual bleeding associated with uterine fibroids. Consistent with its mechanism of action, elagolix exhibited dose‐dependent suppression of estradiol (E2) in clinical studies. A dose‐response model that describes the relationship between elagolix dosages and average E2 levels was combined with a previously published quantitative systems pharmacology (QSP) model of calcium homeostasis to predict bone mineral density (BMD) changes during and following elagolix treatment. In the QSP model, changes in E2 levels were linked to downstream changes in markers of bone resorption (carboxyterminal cross‐linked telopeptide of type 1 collagen [CTX]), formation (N‐terminal propeptide of type 1 procollagen [P1NP]) and BMD. The BMD, CTX, and P1NP predictions by the QSP model were validated against observed data from four phase III clinical trials of elagolix in premenopausal women with endometriosis. BMD, CTX, and P1NP were successfully described by the QSP model, without any model fitting, suggesting that the model was validated for further predictions of elagolix effects on BMD. Simulations using the validated QSP model demonstrated that elagolix 150 mg once daily dosing for 24 months is predicted to result in −0.91% change from baseline in lumbar spine BMD. The QSP model simulation results were part of the totality of evidence to support the approved duration of therapy for elagolix 150 mg once daily in patients with endometriosis.

Selenium: A Trace Element for a Healthy Skeleton - A Narrative Review

Inadequate serum selenium levels may delay the growth and physiological changes in bone metabolism. In humans, reduced serum selenium concentrations are associated with both increased bone turnover and reduced bone mineral density. Moreover, a reduced nutritional intake of selenium may lead to an increased risk of bone disease. Therefore, selenium is an essential nutrient playing a role in bone health, probably due to specific selenium-proteins. Some selenium-proteins have an antioxidation enzymatic activity and participate in maintaining the redox cellular balance, regulating inflammation and proliferation/differentiation of bone cells too. At least nine selenium-proteins are known to be expressed by fetal osteoblasts and appear to protect bone cells from oxidative stress at bone microenvironment. Mutations of selenium-proteins and reduced circulating levels of selenium are known to be associated with skeletal diseases such as the Kashin-Beck osteoarthropathy and postmenopausal osteoporosis. In addition, the intake of selenium appears to be inversely related to the risk of hip fragility fractures. Recent data suggest that an altered selenium state may affect bone mass even in males and selenium-proteins and selenium concentrations were positively associated with the bone mass at femoral, total and trochanteric sites. However, selenium, but not selenium-proteins, seems to be associated with femoral neck bone mass after adjustment for many bone fracture risk factors. The present review summarizes the findings of observational and interventional studies, which have been designed for investigating the relationship between selenium and bone metabolism.

Icariin protects against cage layer osteoporosis by intervening in steroid biosynthesis and glycerophospholipid metabolism

Cage layer osteoporosis (CLO) is a common bone metabolism disease in the breeding industry of China. However, effective prevention for CLO has not been developed. Icariin (ICA), the main bioactive component of the Chinese herb Epimedium, has been shown to have good therapeutic effects on bone-related diseases. In this study, the effects of ICA were further evaluated in a low-calcium diet-induced CLO, and a serum metabolomics assay was performed to understand the underlying mechanisms. A total of 144 31-wk-old Lohmann pink-shell laying hens were randomly allocated to 4 groups with 6 replicates of 6 hens per replicate. The 4 dietary treatment groups consisted of a basal diet (3.5% calcium), a low-calcium diet (2.0% calcium), and a low-calcium diet supplemented with 0.5 or 2.0 g/kg ICA. The results showed that ICA exerted good osteoprotective effects on low-calcium diet-induced CLO. ICA significantly increased femur bone mineral density, improved bone microstructure, decreased bone metabolic level, and upregulated mRNA expression of bone formation genes in femoral bone tissue. Serum untargeted metabolomics analysis showed that 8 metabolite levels were significantly changed after ICA treatment, including increased contents of 7-dehydrocholesterol, 7-oxocholesterol, desmosterol, PC (18:1(9Z)/18:1(9Z)), PS (18:0/18:1(9Z)), N,N-dimethylaniline and 2-hydroxy-butanoic acid and decreased N2,N2-dimethylguanosine. Metabolic pathway analysis based on the above 8 metabolites indicated that ICA mainly perturbed steroid biosynthesis and glycerophospholipid metabolism. These findings suggest that ICA can effectively prevent bone loss in low-calcium diet-induced CLO by mediating steroid biosynthesis and glycerophospholipid metabolism and provide new information for the regulation of bone metabolic diseases.

Uncoupled bone remodeling is characteristic of bone damage in premenopausal women with new-onset systemic lupus erythematosus

OBJECTIVE

To investigate the mechanism underlying systemic lupus erythematosus (SLE)-related bone loss by evaluating the bone mineral density (BMD) and bone turnover markers (BTMs) in premenopausal patients with new-onset SLE without any treatment.

METHODS

BMD and BTMs of 106 premenopausal patients with new-onset SLE and 64 gender-, age- and body mass index (BMI)-matched healthy controls were analyzed. BMD was determined using dual energy X-ray absorptiometry (DXA). Serum BTMs were measured.

RESULTS

Hip and lumbar spine BMD in premenopausal patients with new-onset SLE was significantly decreased compared with healthy controls. Higher rate of osteoporosis was observed in new-onset SLE patients (25% vs. 1%). Moreover, uncoupled bone remodeling evidenced by an increase in bone resorption marker β-CTX (685.9 ± 709.6 pg/mL vs. 395.4 ± 326.0 pg/mL, P < 0.05) and decrease in bone formation markers PINP (37.4 ± 33.0 ng/mL vs. 46.1 ± 20.9 ng/mL, P < 0.05) and OC (11.4 ± 9.8 ng/mL vs. 18.2 ± 8.6 ng/mL, P < 0.05) was observed in premenopausal patients with new-onset SLE compared with healthy controls. Univariate correlation analyses showed negative correlations between OC and SLE Disease Activity Index (SLEDAI), and positive correlations between β-CTX and SLEDAI. SLE patients positive for dsDNA, nucleosome showed lower OC and higher β-CTX.

CONCLUSION

Premenopausal patients with new-onset SLE had decreased BMD and abnormal bone metabolism with increased β-CTX and decreased OC and P1NP levels, indicating uncoupled bone remodeling in new-onset SLE patients. Disease activity and abnormal immunity, especially the amount of antibodies in SLE patients, were strongly associated with abnormality of bone metabolism.

Lower Serum Irisin Levels Are Associated with Increased Osteoporosis and Oxidative Stress in Postmenopausal

Background

Irisin as an exercise-induced myokine was proposed to improve bone health. This study investigated the role of serum irisin (s-irisin) in patients with osteoporosis (OP) through correlating to most biological bone markers and oxidative stress.

Methods

A cross-sectional study recruited an eligible 175 postmenopausal women at Al-Hussien Teaching Hospital, Iraq. They were scanned by DEXA and stratified into two groups based on T-score; the first 95 patients as control group (GI) with -1 ≤ T-score and the second 80 patients as cases group (GII) with T-score ≤ -2.5. Demographic criteria were age, bone mineral density (BMD, g/cm2) and T-score. Serum irisin, total serum calcium (s-calcium), serum inorganic phosphate (s-phosphate), serum alkaline phosphatase (s-ALP), serum 25 [OH] vitamin D, the serum parathyroid hormone (s-PTH), serum Carboxy terminal collagen crosslinks (CTx), serum procollagen type I C-termidnal peptide (s-PICP), serum malondialdehyde (s-MDA) and serum superoxide dismutase (s-SOD) were collected from blood samples.

Results

Serum irisin were 31.84 ± 2.65 vs. 20.88 ± 2.71 ng/mL for control and trial groups, respectively. Lower levels of BMD, T-score, 25 [OH] vitamin D, and s-irisin along with a higher serum levels of PTH, CTx, PICP, MDA and SOD were observed in patients with osteoporosis. All parameters were statistically meaningful upon correlation (p< 0.0001), except age and s-calcium (p= 0.0088 and p= 0.187, respectively).

Conclusion

The results showed that, a significantly lower serum irisin levels among osteoporosis women, was intimately correlated to most bone turnover markers and it can be considered as encouraging results for clinical application in prediction and treatment of osteoporosis.

Effect of zoledronic acid on bone nanocomposites organization and prevention of bone mineral density loss in ovariectomized rats

OBJECTIVES

Osteoporosis often occurs in individuals of different age groups, frequently during menopause and after ovariectomy. It increases the risk of pathological fractures almost twice. The aim of our research was to assess bone metabolism, nanocomposite structure of the tibia under conditions of ovariectomy and zoledronic acid treatment.

METHODS

X-ray diffraction has been performed for nanostructure analysis of mineral crystallites and crystal lattice of hydroxyapatite in the tibia samples of ovariectomized rats with additional application of bisphosphonate zoledronic acid (0.025 mg/kg). Markers of remodeling - osteocalcin, alkaline phosphatase, tartrate resistant acid phosphatase 5b - were determined. Quantitative amount of calcium in the bones was detected by atomic absorption method.

RESULTS

Zoledronic acid prevented loss of mineral mass after ovariectomy. Rats after ovariectomy, treated with zoledronic acid, showed statistically higher (р<0.05) values of crystalline phase and calcium content compared with the SHAM-surgery and ovariectomy groups (р<0.05). Zoledronic acid inhibited bone remodeling, which is proved by tartrate resistant acid phosphatase 5b reduction and inhibition of osteoclasts during the experiment.

CONCLUSIONS

These results enable to suggest that zoledronic acid can improve mineral mass of the bone during menopause in individuals of different age groups.

No Interaction Effect between Interleukin-6 Polymorphisms and Acid Ash Diet with Bone Resorption Marker in Postmenopausal Women

Background: Evidence is growing that a high-acid diet might accelerate the rate of bone loss, and gene polymorphisms such as Interleukin 6 (IL6) -174G/C and -572G/C are related to bone deterioration. However, no study of the interaction between diet and IL6 polymorphisms has been conducted among Asians. Thus, the objective of this study was to determine whether IL6 gene polymorphisms modified the association between dietary acidity and the rate of bone resorption. Methods: This cross-sectional study recruited 203 postmenopausal women (age ranged from 51 to 85 years old) in community settings. The dietary intakes of the participants were assessed using a validated interviewer-administered semi-quantitative food frequency questionnaire (FFQ), while dietary acid load (DAL) was estimated using net endogenous acid production (NEAP). Agena^® MassARRAY genotyping analysis and serum collagen type 1 cross-linked C-telopeptide (CTX1) were used to identify the IL6 genotype and as a bone resorption marker, respectively. The interactions between diet and single-nucleotide polymorphisms (SNPs) were assessed using linear regressions. Results: A total of 203 healthy postmenopausal women aged between 51 and 85 years participated in this study. The mean BMI of the participants was 24.3 kg/m². In IL6 -174 G/C, all the participants carried the GG genotype, while the C allele was absent. Approximately 40% of the participants had a high dietary acid load. Dietary acid load (B = 0.15, p = 0.031) and the IL6 -572 CC genotype group (B = 0.14, p = 0.044) were positively associated with a higher bone resorption. However, there was no moderating effect of the IL6 genetic polymorphism on the relationship between and acid ash diet and bone resorption markers among the postmenopausal women (p = 0.79). Conclusion: High consumption of an acid ash diet and the IL6 -572 C allele seem to attribute to high bone resorption among postmenopausal women. However, our finding does not support the interaction effect of dietary acidity and IL6 (-174G/C and -572G/C) polymorphisms on the rate of bone resorption. Taken together, these results have given scientific research other candidate genes to focus on which may interact with DAL on bone resorption, to enhance planning for preventing or delaying the onset of osteoporosis among postmenopausal women.

Metformin and Bone Metabolism in Endogenous Glucocorticoid Excess: An Exploratory Study

CONTEXT

Glucocorticoid excess exhibits multiple detrimental effects by its catabolic properties. Metformin was recently suggested to protect from adverse metabolic side-effects of glucocorticoid treatment. Whether metformin is beneficial in patients with endogenous glucocorticoid excess has not been clarified.

OBJECTIVE

To evaluate the phenotype in patients with endogenous Cushing's syndrome (CS) treated with metformin at the time of diagnosis.

PATIENTS AND METHODS

As part of the German Cushing's Registry we selected from our prospective cohort of 96 patients all 10 patients who had been on pre-existing metformin treatment at time of diagnosis (CS-MET). These 10 patients were matched for age, sex and BMI with 16 patients without metformin treatment (CS-NOMET). All patients had florid CS at time of diagnosis. We analyzed body composition, metabolic parameters, bone mineral density and bone remodeling markers, muscle function and quality of life.

RESULTS

As expected, diabetes was more prevalent in the CS-MET group, and HbA1c was higher. In terms of comorbidities and the degree of hypercortisolism, the two groups were comparable. We did not observe differences in terms of muscle function or body composition. In contrast, bone mineral density in metformin-treated patients was superior to the CS-NOMET group at time of diagnosis (median T-Score -0.8 versus -1.4, p = 0.030). CS-MET patients showed decreased β-CTX levels at baseline (p = 0.041), suggesting reduced bone resorption under metformin treatment during glucocorticoid excess.

CONCLUSION

This retrospective cohort study supports potential protective effects of metformin in patients with endogenous glucocorticoid excess, in particular on bone metabolism.

Consensus Statement on the Use of Bone Turnover Markers for Short-Term Monitoring of Osteoporosis Treatment in the Asia-Pacific Region

Osteoporosis is a major health issue. By 2050, a greater than 2-fold increase in patients number with hip fractures will occur in Asia representing 50% of all hip fractures worldwide. For the Asia-Pacific (AP) region, more efforts on controlling osteoporosis and the subsequent fractures are crucial. Bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA) is commonly used to diagnose osteoporosis and monitor osteoporosis treatment. However, the inconvenience, cost, limited availability of DXA and the delay in detection of BMD changes after treatment initiation support an important role for bone turnover markers (BTMs), as short-term tools to monitor therapy. With regards to low adherence rates of medical treatment of osteoporosis, the experts reached consensus on the use of BTMs for both raising awareness and short-term monitoring of osteoporosis treatment in the AP region. The experts endorse the use of BTMs, especially serum C-terminal telopeptide of type 1 collagen (CTX) and serum procollagen type 1 N propeptide (P1NP), as short-term monitoring tools to help clinicians assess the responses to osteoporosis therapies and appropriately adjust treatment regimens earlier than BMD. Either the absolute values or the degree of change from baseline in BTMs can be used to monitor the potential efficacy of osteoporosis therapies. The use of BTMs can be incorporated in osteoporosis care programs, such as fracture liaison service (FLS), to improve patient adherence and treatment outcomes. Encouraging sufficient reimbursement from health care systems may facilitate widespread use of BTMs in clinical practice in the AP region.

Tocilizumab controls bone turnover in early polymyalgia rheumatica

OBJECTIVES

This study explores changes in the bone homeostasis by testing the N-terminal collagen type I extension propeptide (PINP) marker for osteo-formation and the carboxy-terminal region of collagen type I (CTX-I) marker for osteo-resorption in patients taking tocilizumab for polymyalgia rheumatica (PMR).

METHODS

Twenty patients were included in the prospective open-label TENOR study (Clinicaltrials.gov NCT01713842) and received three monthly tocilizumab infusions, followed by corticosteroids starting at week (W) 12. PINP and CTX-I were tested at inclusion (W0), after tocilizumab but before steroid initiation (W12), at the end of the protocol (W24) and were compared to healthy controls. Information regarding disease activity, bone mineral density using scanographic bone attenuation correlation (SBAC), inflammatory parameters and interleukin (IL)-6 levels were collected during the follow-up of the patients.

RESULTS

PMR patients were characterised by a reduction in bone mineral density and a higher level of CTX-I relative to healthy controls matched in age and sex at baseline. PINP levels increased at W12 (P< 0.001, versus W0) following tocilizumab introduction and CTX-I levels decreased at W24 and after steroid initiation (P=0.001, versus W0). Such modifications explain the altered correlation observed between PINP and CTX-I at W0 (r=0.255 at W0 versus r=0.641 in healthy controls) and its correction after treatment (r=0.760 at W12 and r=0.767 at W24). Finally, greater changes in PINP were observed in patients whose circulating IL-6 levels decreased after tocilizumab therapy.

CONCLUSIONS

Control of bone turnover, in part through the inhibition of the IL-6 axis, is observed during tocilizumab and subsequent steroid treatment of PMR.

The Bone Metabolic Response to Exercise and Nutrition

Bone (re)modeling markers can help determine how the bone responds to different types, intensities, and durations of exercise. They also might help predict those at risk of bone injury. We synthesized evidence on the acute and chronic bone metabolic responses to exercise, along with how nutritional factors can moderate this response. Recommendations to optimize future research efforts are made.

Clinician's guide for the management and research of osteoporosis in North African men: a guidelines comparison, a cost-effectiveness analysis, and a local algorithm

A local management algorithm and practice recommendations for the management of osteoporosis in Egyptian males were developed after assessing the applicability of current international recommendations and the cost effectiveness of local drugs. A systematic review and sensitivity analyses augmented the quality of the research efforts.

PURPOSE

Osteoporosis affects both men and women; however, no local recommendations for the condition are available for the male population. Therefore, this study was undertaken to produce recommendations for men based on the applicability of current international recommendations and the cost effectiveness of local drugs.

METHODS

The International Osteoporosis Foundation website, EMBASE, and SUMSEARCH-2 databases were searched to identify all guidelines that included recommendations for males. Regional and international guidelines were then appraised using the Advancing Guideline Development, Reporting, and Evaluation in Healthcare-II tool. A cost-effectiveness analysis was conducted using the perspective of an uninsured patient, international outcomes, and local costs. Recommendations were then formulated using the Grading of Recommendations Assessment, Development and Evaluation guidelines, and symbolic representations.

RESULTS

Twenty-six guidelines were found. Only one of the guidelines focused entirely on males, with the remainder making inferences based on recommendations for females. Six regional guidelines were mainly of low quality. Alendronate was considered to be the most cost-effective drug, while teriparatide was found to be unaffordable.

CONCLUSION

Recommendations for men with osteoporosis are based on that of women, and the topic lacks exploration in the Middle East. International recommendations and other guidelines were evaluated and adopted to create guidance for the management of osteoporosis in men for application in Egypt.

Spironolactone reduces biochemical markers of bone turnover in postmenopausal women with primary aldosteronism

CONTEXT

Primary aldosteronism (PA) is the most frequent form of endocrine hypertension. Besides its deleterious impact on cardiovascular target organ damage, PA is considered to cause osteoporosis.

PATIENTS AND METHODS

We assessed bone turnover in a subset of 36 postmenopausal women with PA. 18 patients had unilateral PA and were treated by adrenalectomy, whereas 18 patients had bilateral PA and received mineralocorticoid receptor antagonist (MRA) therapy respectively. 18 age- and BMI-matched females served as controls. To estimate bone remodeling, we measured the bone turnover markers intact procollagen 1 N-terminal propeptide, bone alkaline phosphatase, osteocalcin and tartrate resistant acid phosphatase 5b in plasma by chemiluminescent immunoassays at time of diagnosis and one year after initiation of treatment.

STUDY DESIGN

Observational longitudinal cohort study.

SETTING

Tertiary care hospital.

RESULTS

Compared with controls, patients with PA had mildly elevated osteocalcin at baseline (p = 0.013), while the other bone markers were comparable between both groups. There were no differences between the unilateral and the bilateral PA subgroup. One year after initiation of MRA treatment with spironolactone bone resorption and bone formation markers had significantly decreased in patients with bilateral PA. In contrast, patients adrenalectomized because of unilateral PA showed no significant change of bone turnover markers.

CONCLUSION

This study shows that aldosterone excess in postmenopausal women with PA is not associated with a relevant increase of bone turnover markers at baseline. However, we observed a significant decrease of bone markers in patients treated with spironolactone, but not in patients treated by adrenalectomy.

The Effect of Biochemical Remission on Bone Metabolism in Cushing's Syndrome: A 2-Year Follow-Up Study

Endogenous Cushing's syndrome (CS) is a rare cause of secondary osteoporosis. The long-term consequences for bone metabolism after successful surgical treatment remain largely unknown. We assessed bone mineral density and fracture rates in 89 patients with confirmed Cushing's syndrome at the time of diagnosis and 2 years after successful tumor resection. We determined five bone turnover markers at the time of diagnosis, 1 and 2 years postoperatively. The bone turnover markers osteocalcin, intact procollagen-IN-propeptide (PINP), alkaline bone phosphatase, CTX-I, and TrAcP 5b were measured in plasma or serum by chemiluminescent immunoassays. For comparison, 71 sex-, age-, and body mass index (BMI)-matched patients in whom Cushing's syndrome had been excluded were studied. None of the patients received specific osteoanabolic treatment. At time of diagnosis, 69% of the patients had low bone mass (mean T-score = -1.4 ± 1.1). Two years after successful surgery, the T-score had improved in 78% of patients (mean T-score 2 years postoperatively -1.0 ± 0.9). The bone formation markers osteocalcin and intact PINP were significantly decreased at time of diagnosis (p ≤ 0.001 and p = 0.03, respectively), and the bone resorption marker CTX-I and TrAcP 5b increased. Postoperatively, the bone formation markers showed a three- to fourfold increase 1 year postoperatively, with a moderate decline thereafter. The bone resorption markers showed a similar but less pronounced course. This study shows that the phase immediately after surgical remission from endogenous CS is characterized by a high rate of bone turnover resulting in a striking net increase in bone mineral density in the majority of patients. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

The challenge of long-term adherence: The role of bone turnover markers in monitoring bisphosphonate treatment of osteoporosis

Oral Bisphosphonates (BPs) are the mainstay of osteoporotic treatment, however long-term adherence remains a challenge, primarily owing to the chronic character of the disease and the regimen complexity. Poor compliance has been shown to have a clear link to fracture risk. The role of bone turnover markers (BTMs) as a tool to ascertain adherence and response to therapy is supported by their rapid response to treatment; a decrease in values is witnessed within days or weeks of commencing treatment. A greater reduction of serum CTX and NTX is evidenced with alendronate and ibandronate compared to risedronate. A change in bone formation BTMs appears to be related to vertebral fracture risk reduction, whereas no significant relationship is evident for hip and non-vertebral fractures. The utility of BTMs as an adjunct for monitoring withdrawal of treatment with oral BP has also been suggested. Finally, studies evaluating BTMs as an intervention, failed to demonstrate any effect on adherence. This review explores the challenge of long-term adherence with bisphosphonates and provides an analytic framework with respect to the role of BTMs in monitoring bisphosphonate treatment, adherence and the offset of treatment effect.

Early changes in bone turnover and inflammatory biomarkers and clinically significant bone mineral density loss over 48 weeks among HIV-infected patients with virological failure of a standard first-line antiretroviral therapy regimen in the SECOND-LINE study

OBJECTIVES

We assessed whether changes at week 12 in markers of bone turnover, inflammation, and immune activation were associated with clinically important (≥ 5%) bone mineral density (BMD) loss from baseline to week 48 at the proximal femur (hip) and lumbar spine in the SECOND-LINE study.

METHODS

We measured concentrations of procollagen type 1 pro-peptide (P1NP), carboxyl-terminal collagen crosslinks (CTX), high-sensitivity C-reactive protein (hs-CRP), D-dimer, interleukin (IL)-6, tumor necrosis factor (TNF), neopterin, and soluble CD14 and 163 at weeks 0, 12, and 48 in 123 SECOND-LINE dual-energy X-ray absorptiometry (DXA) substudy participants. Linear regression was used to compare changes in biomarkers. Predictors of ≥ 5% BMD loss were examined using multivariable regression.

RESULTS

The mean age was 38 years, the mean CD4 T-cell count was 252 cells/µL and the mean viral load was 4.2 log HIV-1 RNA copies/mL; 56% of participants were female and 47% were randomized to receive a nucleos(t)ide reverse transcriptase inhibitor [N(t)RTI]-based regimen [91% (53/58) were randomized to receive a tenofovir disoproxil fumarate (TDF)-containing regimen]. Over 48 weeks, 71% in the N(t)RTI arm experienced ≥ 5% hip BMD loss vs. 29% in the raltegravir arm (P = 0.001). Week 12 changes in P1NP and CTX were significantly greater among patients experiencing ≥ 5% hip BMD loss, patients randomized to N(t)RTI, and male patients. Predictors of ≥ 5% hip BMD loss at week 48 were P1NP increase [odds ratio (OR) 5.0; 95% confidence interval (CI) 1.1-27; P < 0.043]; N(t)RTI randomization (OR 6.7; 95% CI 2.0-27.1; P < 0.003), being African, higher baseline CD4 T cell count , and smoking.

CONCLUSIONS

In a diverse cohort of viraemic HIV-infected patients, switching to second-line antiretroviral therapy (ART) was associated with clinically significant BMD loss, which was correlated with an early increase in P1NP. Measurement of P1NP may facilitate timely interventions to reduce rapid BMD loss among at-risk patients.

Visceral Fat Is a Negative Determinant of Bone Health in Obese Postmenopausal Women

The protective effect of obesity on bone health has been challenged by studies that link visceral adiposity to poor bone microarchitecture in young obese men and women. In postmenopausal women, the role of visceral adipose tissue (VAT) on bone turnover markers (BTMs) has not been investigated. The aim was to investigate the impact of VAT on BTMs, total bone mineral density (BMD), vitamin D metabolites and parathyroid levels (1-84 PTH) levels in postmenopausal women. A total of 76 lean and overweight women (without osteoporosis) underwent VAT measurements by dual-energy X-ray absorptiometry (iDXA). Blood samples were analyzed for serum C-terminal telopeptide of type 1 collagen (CTX-1), osteocalcin, bone-specific alkaline phosphatase (bone ALP), 1–84 PTH and vitamin D (25 hydroxyvitamin D, 25(OH)D) levels. VAT volumes ranged from 91 to 3392 cm³ and body mass index (BMI) ranged from 18.3 to 53.9 kg/m². Women in the highest VAT quartile had significantly lower CTX-1, 25(OH)D, osteocalcin and the highest BMD (p < 0.05, for all). While VAT positively associated with BMD, after controlling for BMI, VAT was a negative predictor of BMD (β = 0.368, p < 0.05). VAT was an independent negative predictor of CTX-1 (β = −0.263, p < 0.05) and osteocalcin levels (β = −0.277, p < 0.05). Among all measures of adiposity, VAT was the strongest independent determinant of BMD and BTMs. In clinical settings, VAT, and not BMI, may be a sensitive predictor of bone health in obese women.

Associations between the serum levels of selected bone turnover markers and biological traits in nursing home women aged 80+ without inflammation. A pilot study

BACKGROUND

Bone turnover markers (BTM) reflect the status of bone remodeling processes responsible for bone mineral density. The existing body of evidence that osseous tissue can interact with many other body tissues and organs suggests that the cross-talks can lead to different relationships. The biological traits associated with BTMs have not been thoroughly studied in the elderly despite bone turnover being known to increase with age.

OBJECTIVE

To determine whether the C-terminal crosslinking telopeptides of type I collagen (CTXI) and the serum levels of total (TAP) and bone-specific (BAP) alkaline phosphatase are associated with the biological traits in nursing home women aged 80-92 years without inflammation and, if so, to indicate the best predictors of these BTM's blood concentrations.

METHODS

A group of 64 female volunteers aged 80 years and older, the residents of nursing homes, were screened for the study. Fifty two women were ineligible as they met the exclusion criteria. As a result, the study group consisted of 12 participants (85.1 ± 3.9 years; 58.1 ± 8.7 kg; 1.52 ± 0.06 m), all having blood C-reactive protein (CRP) levels below 3 mg/l. Also assessed were the participants' morphology, glucose and insulin levels, lipid profiles, CTXI, TAP, and BAP. Other measured parameters included body composition, resting heart rate and arterial blood pressure, isometric knee extension peak torque (IKEPT), and walking capacity (6-min walk test). The statistical analysis was performed using Pearson's correlation coefficients, the Benjamini-Hochberg procedure, and a stepwise multiple regression analysis with backward elimination.

RESULTS

Inverse correlations were found between CTX-I and hemoglobin concentration (HGB) (r = -0.680; p = .015), red blood cells count (RBC) (r = -0.664; p = .019), fat-free mass (r = -0.633; p = .027), body weight (r = -0.589; p = .044), and total cholesterol (r = -0.581; p = .048). The multiple regression analysis of CTX-I showed that body weight was the only independent variable that was statistically significant (r2 = 0.346; p < .05; SEE = 0.347 ng/ml). BAP was positively correlated with double product (DP) (r = 0.742; p = .006), RBC (r = 0.650; p = .022), HGB (r = 0.637; p = .026), mean arterial pressure (MAP) (r = 0.622; p = .031), diastolic blood pressure (DBP) (r = 0.612; p = .034), body height (r = 0.603; p = .038), IKEPT (r = 0.565; p = .056), and systolic blood pressure (SBP) (r = 0.538; p = .071). BAP, a dependent variable, was the most closely correlated with DP (r² = 0.550; p < .01; SEE = 9.161 U/l). TAP was also significantly associated with DP (r = 0.775; p = .003), with the association being stronger than between BAP and DP (r² = 0.600; p < .01; SEE = 1000.5 beats/min*mm Hg).

CONCLUSIONS

In relatively healthy the oldest-old nursing home women without inflammation, total body weight was the best predictor of bone resorption shown by the CTX-I concentration, whereas the rate pressure product (DP) turned out to best predict osteoblastic activity determinable from serum alkaline phosphatase activity. The results of the study suggest that the activity of serum TAP and BAP can be enhanced by different mechanisms.