Reference Intervals for Bone Turnover Markers in Korean Healthy Women

Update on the role of bone turnover markers in the diagnosis and management of osteoporosis: a consensus paper from The European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), International Osteoporosis Foundation (IOF), and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)

PURPOSE

The International Osteoporosis Foundation (IOF) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) have proposed procollagen type I N propeptide (PINP) and β isomerized C-terminal telopeptide of type I collagen (β-CTX-I) as reference bone turnover markers (BTMs) for osteoporosis. This report examines the published literature since the 2011 IOF-IFCC position paper in order to determine the clinical potential of the reference BTMs and newer markers for the prediction of fracture risk and monitoring the treatment of osteoporosis.

METHODS

Evidence for the relationship between BTMs and subsequent fractures was gathered from prospective studies through literature review of the Medline database from years 2011 to May 2024. The impact of treatment on BTMs was also studied by examining publications in that period. Studies of the accuracy of BTMs in the assessment of bone turnover in the setting of advanced chronic kidney disease were also examined.

RESULTS

Increased BTM concentrations are associated with higher fracture risk in postmenopausal women. PINP and β-CTX-I measured in blood are associated with fracture risk but their interaction with other risk factors has not been sufficiently studied limiting their incorporation into fracture risk algorithms. Treatment-induced changes in PINP and β-CTX-I account for a substantial proportion of fracture risk reduction and are useful for improving adherence; they are recommended for inclusion in studies to examine adherence in individual patients. However, total PINP (tPINP) and β-CTX-I may be elevated in CKD due to renal retention. Bone alkaline phosphatase (BALP), intact PINP (iPINP), and tartrate resistant acid phosphatase 5b (TRACP5b) show the most promise in discriminating high and low turnover bone diseases in patients with advanced CKD and for predicting fracture risk, monitoring treatment response, and assessing the risk of treatment-related complications.

CONCLUSION

We re-affirm the use of serum/plasma tPINP and plasma β-CTX-I as reference BTMs with appropriate patient preparation and sample handling and measurement by standardized/harmonized assays in clinical studies to accumulate further data, and for monitoring treatment of osteoporosis in the setting of normal renal function in clinical practice. BALP and TRACP5b, measured by standardized assays, are recommended as reference BTMs for CKD-associated osteoporosis and should be included in observational and intervention studies to ascertain their utility for risk-evaluation, treatment initiation, and assessment of treatment response in CKD-associated osteoporosis.

Bone turnover markers reference database in five Southeast Asian countries

Osteoporosis is highly prevalent, particularly in developing countries. However, bone turnover marker reference ranges for management of osteoporosis in Asian population are yet to be explored and established. Thus, this study aims to develop a regional bone turnover markers (BTMs) reference database by combining country-specific reference database from five ASEAN countries: Malaysia, the Philippines, Singapore, Thailand, and Vietnam. We established a healthy reference population of 746 healthy premenopausal women aged 20 to 44 years old. Serum Procollagen 1 N-Terminal Propeptide (P1NP), Osteocalcin (OC), and Beta-Crosslaps (CTX) concentrations were measured using an automated immunoassay analyzer system, the cobas® modular analyzer systems (Roche Diagnostic Gmbh). The reference interval was defined as the central 95 % range. The estimated reference interval for CTX was 128 to 811 ng/L, OC was 9.0 to 33.0 μg/L, and for P1NP, the range was 22.8 to 96.5 μg/L. Comparison across countries showed that Singaporeans had the highest levels of median CTX along with Thais and Filipinos, who had significantly higher levels of P1NP and OC. Exploratory analysis on the associations with age showed that BTMs decreased with increasing age at 20 to 29 years old and plateaued after 30 years old. When excluding participants in their 20s, the reference interval estimated were CTX: 117-678 ng/L, P1NP: 21.6-85.8 μg/L and OC: 3.5-27.0 μg/L respectively. To the best of our knowledge, this is the first study to report BTMs reference intervals based on a healthy premenopausal Southeast Asian population which will contribute to the appropriate assessment and monitoring of bone turnover rate in the evaluation and management of osteoporosis in the Southeast Asian region. LAY SUMMARY: Osteoporosis is a common health issue, especially in developing countries. However, there is a lack of information on bone health markers specific to the Southeast Asian population. This study aimed to fill this gap by creating a reference database for bone turnover markers (BTMs) in Southeast Asian countries, including Malaysia, the Philippines, Singapore, Thailand, and Vietnam. The researchers studied 746 healthy women aged 20 to 44 years and measured blood markers related to bone health. The reference interval, representing the normal range, was determined. For example, the normal range for CTX was found to be 128 to 811 ng/L, for Osteocalcin was 9.0 to 33.0 μg/L, and for P1NP, the range was 22.8 to 96.5 μg/L. When excluding participants in their 20s, the reference intervals estimated were CTX: 117-678 ng/L, P1NP: 21.6-85.8 μg/L and OC: 3.5-27.0 μg/L respectively. Comparing the results across countries, Singaporeans, Thais, and Filipinos showed variations in their biochemical bone marker levels. Additionally, the study observed changes in the levels with age, with a decrease in BTMs observed after the age of 30. This groundbreaking study provides the first-ever reference intervals for BTMs in a healthy premenopausal Southeast Asian population. These findings will help in the proper assessment and monitoring of bone health, contributing to the management of osteoporosis in the Southeast Asian region.

Comparison of bone turnover suppression in atypical femoral fractures and osteoporotic hip fractures

We aimed to compare the extent of bone turnover suppression between patients with atypical femoral fractures (AFFs) and osteoporotic hip fractures (typical femur fractures, TFFs) using a one-to-one matching strategy. A single-center retrospective comparison of females aged ≥ 60 years who underwent operative treatment for AFFs and TFFs between January 2010 and March 2021 was conducted. Demographic characteristics and clinical data including fracture site, past medical history, bone mineral density (BMD), bisphosphonate (BP) medication history, and serum bone turnover marker (BTM) levels were examined. Moreover, we performed a logistic regression analysis to determine the risk factors for AFFs and a one-to-one matched-pair analysis to compare various BTMs. Overall, 336 consecutive females were included: 113 with AFFs and 213 with TFFs. The mean age, BMI, and lowest BMD T-score were 78.6 years, 22.8 kg/m2, and -3.3, respectively. Patients with AFF were younger, had lower BMD, higher BMI, higher prevalence of rheumatoid arthritis, a greater proportion with previous steroid or BP use, and a longer history of BP use than patients with TFF. The 48:48 matched-pair analysis revealed higher serum 25(OH) vitamin-D (30.5 vs 18.2 ng/mL, P < 0.001) and calcium levels (8.8 vs 8.3 ng/dL, P = 0.009) and lower serum CTX levels (0.33 vs 0.54 ng/mL, P = 0.010) in the AFF group than in the TFF group, suggesting a more suppressed bone remodeling. No differences in the other BTM levels were found. Despite identical histories and durations of BP use, the AFF group exhibited lower CTX levels, suggesting more suppressed bone remodeling. This observation leads us to infer that more suppressed bone remodeling, indicated by lower CTX levels, could be linked to the occurrence of AFFs.

Oral daily PTH(1-34) tablets (EB613) in postmenopausal women with low BMD or osteoporosis: a randomized, placebo-controlled, 6-month, phase 2 study

Anabolic treatment is indicated for high and very-high risk patients with osteoporosis, but acceptance is limited because current anabolic medications require subcutaneous injections. The purpose of this study was to assess the effects of a novel orally administered PTH tablet on serum markers of bone formation (PINP and osteocalcin), bone resorption (crosslinked C-telopeptide [CTX]), BMD, and safety in postmenopausal women with low BMD or osteoporosis. In this 6-mo, double-blind, placebo-controlled study, 161 patients were randomized to oral PTH tablets containing 0.5, 1.0, 1.5, or 2.5 mg or placebo daily. Biochemical markers were assessed at 1, 2, 3, and 6 mo and BMD of LS, TH, and FN was measured at 6 mo. Biochemical marker changes were dose dependent with minimal or no effect at the 2 lowest doses. At the highest dose (2.5 mg once daily), serum PINP and OC levels increased 30% within 1 mo after oral PTH initiation (P < .0001), remained elevated through 3 mo, and were back to baseline at 6 mo. In contrast, serum CTX levels declined 16% and 21% below baseline at 3 and 6 mo, respectively (both P ≤ .02). At 6 mo, 2.5 mg tablets increased mean BMD vs placebo of the LS by 2.7%, TH by 1.8%, and FN by 2.8% (all P ≤ .01). There were no drug-related serious adverse events. The most common adverse events were headache, nausea, and dizziness. In contrast to subcutaneous PTH, the oral PTH tablet appears to increase BMD rapidly by the dual mechanism of stimulating formation and inhibiting bone resorption. This might be the first effective oral anabolic alternative to subcutaneous administration for the treatment of low BMD or osteoporosis.

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.

Effectiveness and Usefulness of Bone Turnover Marker in Osteoporosis Patients: A Multicenter Study in Korea

BACKGROUND

This study aimed to investigate real-world data of C-terminal telopeptide (CTX), propeptide of type I collagen (P1NP), and osteocalcin through present multicenter clinical study, and retrospectively analyze the usefulness of bone turnover markers (BTMs) in Koreans.

METHODS

The study focused on pre- and post-menopausal patients diagnosed with osteoporosis and excluded patients without certain test results or with test intervals of over 1 year. The demographic data and 3 BTMs (CTX, P1NP, and osteocalcin) were collected. The patients were classified by demographic characteristics and the BTM concentrations were analyzed by the group.

RESULTS

Among women with no history of fractures, the levels of P1NP (N=2,100) were 43.544±36.902, CTX (N=1,855) were 0.373 ±0.927, and osteocalcin (N=219) were 10.81 ±20.631. Among men with no history of fractures, the levels of P1NP (N=221) were 48.498±52.892, CTX (N=201) were 0.370±0.351, and osteocalcin (N=15) were 7.868 ±10.674. Treatment with teriparatide increased the P1NP levels after 3 months in both men and women, with a 50% increase observed in women. Similarly, treatment with denosumab decreased the CTX levels after 3 months in both men and women, with a reduction of 50% observed in women.

CONCLUSIONS

The results of this study can contribute to the accurate assessment of bone replacement status in Koreans. We also provide the P1NP level in the Korean population for future comparative studies with other populations.

Sex Differences and Positive Dose-Response Relationships between Serum Osteocalcin Levels and Low Muscle Strength

INTRODUCTION

Impaired handgrip strength is an indication for sarcopenia and frailty screening, and is associated with increased osteoporotic risks and all-cause mortality. Osteocalcin, secreted by osteoblasts, is a versatile factor that participates in bone turnover and muscle adaptation. The role of osteocalcin in muscle strength has mainly been discussed in animal models and requires more human data. The study aimed to investigate the association between the serum osteocalcin level and handgrip strength in middle-aged individuals and older adults with diabetes.

METHODS

Adult participants (aged 40 and above, N = 237) with diabetes were enrolled in a medical center in northern Taiwan. Subjects were divided into normal, low muscle mass without dynapenia, dynapenia without low muscle mass, and groups of low muscle mass with dynapenia according to their handgrip strength and muscle mass measurements. Physical performance, including handgrip strength, repeated sit-to-stand tests, walking speed, and short physical performance batteries, was documented. Body composition was measured by bioelectrical impedance analysis.

RESULTS

The median serum osteocalcin level was highest in the dynapenic group without low muscle mass (median [Q1, Q3], 14.1 [11.2, 16.3] ng/mL). Multivariate logistic regression showed that a higher serum osteocalcin level was associated with worse handgrip strength (OR: 3.89, 95% CI: 1.66-9.10) after adjusting for body mass index (adiposity), skeletal muscle mass index (muscle), and medication with dipeptidyl peptidase-4 inhibitor. Further sex stratification revealed a more significant association between serum osteocalcin level and impaired handgrip strength in women but not in men. The female groups showed increases in the risk of impaired handgrip strength: 4.84-fold in the osteocalcin T2 group (11.4 ≤ osteocalcin <15.0 ng/mL) and 4.54-fold in the osteocalcin T3 group (osteocalcin ≥15.0 ng/mL). Moreover, after adjusting for various confounders, 8.41-fold and 8.03-fold increases in the risk of impaired handgrip strength were observed in the osteocalcin T2 group (11.4≤ osteocalcin <15.0 ng/mL) and osteocalcin T3 group (osteocalcin ≥14.5 ng/mL), respectively.

CONCLUSION

Higher serum osteocalcin is associated with increased risks of impaired handgrip strength and impaired physical performance. Dose-dependent associations were found especially in postmenopausal women but not in men.

Bone Turnover Markers: Basic Biology to Clinical Applications

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

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Bone mineral density, bone microstructure, and bone turnover markers in females with temporomandibular joint osteoarthritis

OBJECTIVE

The pathogenesis of the temporomandibular joint osteoarthritis (TMJ OA) has not been clearly revealed. This study aimed to investigate the pathogenesis of TMJ OA based on bone metabolism.

METHODS

Fifty-nine young (mean age 23.4 ± 3.4 years) and 41 post-menopausal females (mean age 57.2 ± 4.6 years) were enrolled. Areal bone mineral density (aBMD) was measured via dual-energy X-ray absorptiometry of the lumbar spine, femoral neck, total hip, and ultradistal radius. Levels of four bone resorption markers, serum ionized calcium and C-telopeptide of type I collagen (CTx) and urinary N-telopeptide of type I collagen and deoxypyridinoline, two bone formation markers, serum bone alkaline phosphatase and osteocalcin, and serum 25-dihydroxyvitamin D were analyzed at baseline and after 12 months. Condylar bone quality was assessed by 3D reconstructed CT images.

RESULTS

Significant differences in condylar bone quality and aBMDs of the lumbar spine in accordance with TMJ OA stages were observed in young and post-menopausal females. The level of CTx was significantly associated with the development and progression of TMJ OA only in young females, whereas 25-dihydroxyvitamine D demonstrated significant associations in young and post-menopausal females. Progression of TMJ OA was accompanied by reduced condylar bone quality and concomitant with lower lumbar spine aBMDs in young and post-menopausal females.

CONCLUSION

Bone metabolism and condylar quality might be involved in the development and progression of TMJ OA.

CLINICAL RELEVANCE

CTx could be considered as a potential diagnostic and monitoring marker in young females, and vitamin D showed a therapeutic potential for TMJ OA.

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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