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Context Collagen type I C-telopeptide (CTX) and procollagen type I N-terminal propeptide (PINP) are reference bone resorption and formation markers, respectively. Objective To characterize CTX and PINP trajectories across the menopause transition (MT). Methods This 18-year longitudinal analysis of a community-based cohort from the Study of Women's Health Across the Nation included 541 women (126 Black, 90 Chinese, 87 Japanese, 238 White) who transitioned from pre- to postmenopause. Multivariable mixed effects regression fit piecewise linear models of CTX or PINP relative to years from final menstrual period (FMP); covariates were race/ethnicity, body mass index (BMI), and age at FMP. In the referent participant (White, 52.46 years at FMP, BMI 27.12 kg/m2), CTX and PINP were stable until 3 years pre-FMP (premenopause). During the MT (3 years before to 3 years after the FMP), CTX and PINP increased 10.3% (P <.0001) and 7.5% (P <.0001) per year, respectively; MT-related gains totaled 61.9% for CTX and 45.2% for PINP. Starting 3 years post-FMP (postmenopause), CTX and PINP decreased 3.1% (P <.0001) and 2.9% (P <.0001) per year, respectively. Compared with the White participants, during the MT, Chinese participants had larger gains in CTX (P =.01), and Japanese women experienced greater increases in CTX (P <.0001) and PINP (P =.02). In postmenopause, CTX (P =.01) and PINP (P =.01) rose more in Japanese relative to White women. Conclusion CTX and PINP are stable in premenopause, increase during the MT, and decrease in postmenopause. During the MT and postmenopause, bone turnover change rates vary by race/ethnicity. [ABSTRACT FROM AUTHOR]

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 factors (eg, age, gender, ethnicity) and controllable factors, particularly relating to collection conditions (eg, 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. [ABSTRACT FROM AUTHOR]

Higher selenium status has been associated with lower bone turnover markers (BTM) in epidemiological studies. However, the long‐term impact of selenium supplementation on BTMs has not been studied. We investigated the effects of selenium supplementation on BTMs including osteocalcin (OC), procollagen type I N‐terminal propeptide (PINP), collagen type I cross‐linked C‐telopeptide (CTX), and bone alkaline phosphatase (BALP) in the short (6 months) and long term (5 years). A total of 481 Danish men and women (60–74 years) were randomized to receive placebo‐yeast versus 100, 200, or 300 μg selenium as selenium‐enriched yeast daily for 5 years. Plasma selenium concentration was measured using inductively coupled plasma mass spectrometry, and BTMs were measured in nonfasted samples at baseline, 6 months, and 5 years. Data were analyzed by ANCOVA to investigate the shape of the dose‐response relationships. Covariates included age, body mass index, baseline selenium status, baseline BTM, smoking, alcohol, supplement use, and medication. Plasma selenium concentration (mean 86.5 μg/d at baseline) increased significantly with increasing selenium supplementation to 152.6, 209.1, and 253.7 μg/L after 6 months and remained elevated at 5 years (158.4, 222.4, and 275.9 μg/L for 100, 200, and 300 μg supplemental selenium/d, respectively (p < 0.001)). There was no change in plasma selenium concentration in the placebo‐treated group. There was no significant effect of selenium supplementation on OC (6 months p = 0.37; 5 years p = 0.63), PINP (6 months p = 0.37; 5 years p = 0.79), CTX (6 months p = 0.91; 5 years p = 0.58) or BALP (6 months p = 0.17; 5 years p = 0.53). The relatively replete baseline selenium status in the study participants may explain this lack of effect. Testing in more deficient populations may provide further insights into the impact of selenium supplementation on bone health. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). [ABSTRACT FROM AUTHOR]

Summary: Objectives: It is well established that UK Asians typically have lower vitamin D levels than Caucasians. It is also known that vitamin D binding protein (DBP) is lower in some races than Caucasians. To investigate how ethnicity, skin colour and genetic variation affect the response to vitamin D (15000 IU) administered to young Asian and Caucasian men. Design: Prospective, single‐centre clinical trial. Participants: Sixty young men (18‐25 year) of Asian (n = 30) and Caucasian (n = 30) origin. Measurements: We measured serum calcium, phosphate, magnesium, alkaline phosphatase, albumin, parathyroid hormone; total 25 hydroxyvitamin D (25OHD); calculated and directly measured free 25OHD; DBP at baseline and 4 weeks; DBP genotype, skin colour (Fitzpatrick scale), dietary vitamin D and calcium intake at baseline; and urine calcium:creatinine ratio at baseline, 1 and 4 weeks. Results: At baseline, Asians had lower serum total 25OHD (26.4 [13.7] vs 34.1 [12.3] nmol/L P = 0.0272) and DBP (6.7 [3.4] vs 9.6 [4.4] nmol/L; P = 0.0065) but similar free 25OHD (16.7 [10.4] vs 17.8 [7.5] pmol/L P = 0.6530). After dosing, total 25OHD rose similarly in each group (≈56 nmol/L), but measured free 25OHD rose more in Asians (18.1 [9.4] vs 12.2 [13.3] pmol/L P = 0.0464). Lower DBP at baseline, possibly reflecting genotype differences, was associated with a greater change in measured free 25OHD in Caucasians, but not in Asians. Conclusions: Asian compared with Caucasian males had a larger increment in measured free 25OHD following 150 000 units vitamin D3, possibly reflecting differences in DBP affinity for 25OHD. Ethnicity should be considered when devising guidelines for the treatment of vitamin D deficiency. [ABSTRACT FROM AUTHOR]

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