Increased bone resorption and decreased bone formation in Chinese patients with hip fracture

The Effect of Clothing on Vitamin D Status, Bone Turnover Markers, and Bone Mineral Density in Young Kuwaiti Females

Many Arab women in the Gulf region cover their bodies for cultural and religious reasons, limiting the skin's exposure to sunlight and therefore its ability to synthesize vitamin D. The aim of this study is to determine whether the clothing style of Kuwaiti premenopausal women affects their vitamin D status, bone marker expression, and bone density. Three groups of healthy unmarried single Kuwaiti females (20-35 years old; n=30 per group) were recruited randomly from the general community: a control group who wear Western-style clothing (unveiled group), a group who wear a hejab that covers the whole body except for the face and hands (hejab group), and a group who wear a black veil with the entire body covered (veiled group). Bone mineral density (BMD), bone markers (procollagen type 1 N-terminal propeptide [P1NP], osteocalcin, and β-CrossLaps), 25-hydroxy vitamin D, intact parathyroid hormone [iPTH], and calcitonin were measured. The bone marker osteocalcin was significantly higher in the hejab group compared to the control group, whereas P1NP and β-CrossLaps were significantly higher in the veiled group compared to the control group. 25-hydroxy vitamin D, iPTH, calcitonin, and BMD were not significantly different across the three groups despite the observed elevation in bone turnover markers. The majority of participants in all three groups exhibited vitamin D deficiency; however, the lowest vitamin D levels were observed among the hejab and veiled participants. These findings suggest that clothing style may contribute to vitamin D deficiency in young Kuwaiti women.

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

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

Biochemical Markers of Bone Turnover and Fracture Prediction

Low bone mineral density is a strong risk factor for fractures in the older woman. Biochemical markers of bone turnover may predict fracture risk independently of bone mineral density. High levels of bone resorption markers are associated with increased risk of fracture in both retrospective and prospective studies, although the evidence for bone formation markers and fracture risk is equivocal. For example, the risk of fracture is increased up to two-fold in women with elevated levels of several markers of bone resorption. Prediction models have been developed to predict the 10–year risk of fracture using bone mineral density and biochemical markers of bone turnover and these could prove very useful in clinical practice.

The Chinese skeleton: insights into microstructure that help to explain the epidemiology of fracture

Osteoporotic fractures are a major public health problem worldwide, but incidence varies greatly across racial groups and geographic regions. Recent work suggests that the incidence of osteoporotic fracture is rising among Asian populations. Studies comparing areal bone mineral density and fracture across races generally indicate lower bone mineral density in Asian individuals including the Chinese, but this does not reflect their relatively low risk of non-vertebral fractures. In contrast, the Chinese have relatively high vertebral fracture rates similar to that of Caucasians. The paradoxically low risk for some types of fractures among the Chinese despite their low areal bone mineral density has been elucidated in part by recent advances in skeletal imaging. New techniques for assessing bone quality non-invasively demonstrate that the Chinese compensate for smaller bone size by differences in hip geometry and microstructural skeletal organization. Studies evaluating factors influencing racial differences in bone remodeling, as well as bone acquisition and loss, may further elucidate racial variation in bone microstructure. Advances in understanding the microstructure of the Chinese skeleton have not only helped to explain the epidemiology of fracture in the Chinese, but may also provide insight into the epidemiology of fracture in other races as well.

Bone remodeling markers: assessment of fracture risk and fracture risk reduction

There is an increasing repertoire of laboratory tests available for assessing the bone remodeling process. Biochemical markers of bone remodeling can be measured in serum or urine, and have a number of potential roles in the management of fracture risk. Differences in remodeling between individuals might be related to fracture risk and could be used to target therapy. Change in remodeling with therapy could be related to fracture risk reduction and the choice of therapy could be influenced by knowledge of bone remodeling. Biochemical therapeutic monitoring may improve patient understanding and therapeutic adherence. The rate of bone remodeling is weakly predictive of fracture risk in individuals who are not receiving therapy; however, it is not clear whether this is independent of other risk factors. There is increasing evidence that change in bone mineral density does not explain fracture risk reduction with antiresorptive therapies, and that therapeutic benefit might be explained by change in bone turnover. Additional studies and information are required to allow these scientific advances to be translated into cost-effective and validated clinical protocols. Optimizing the precision and accuracy of bone turnover assessment remains an important priority.

Biochemical markers of bone remodeling

Because of the aging population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to everyday clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis, and follow-up of such pathologies has markedly grown. Together with clinical and imaging techniques, laboratory tests play an important role in the assessment and differential diagnosis of metabolic bone disease.

Comparison of biochemical markers of bone turnover and bone mineral density between hip fracture and vertebral fracture

Bone density and the biochemical markers of bone turnover were compared between 26 hip-fracture patients and 41 vertebral-fracture patients after age adjustment to investigate whether or not type of osteoporosis differs between hip fracture and vertebral fracture. C-Terminal propepides of type I collagen (PIPC) was lower in hip fracture than vertebral fracture. The other bone formation markers (bone-specific alkaline phosphatase [ALP], osteocalcin) tended to be lower, and bone resorption markers (deoxypyridinoline, C-telopeptide crosslinking of type I collagen [CTX] tended to be higher in hip fracture compared to vertebral fracture. Mean of Z-scores of spine bone mineral density (BMD) in hip fracture and vertebral fracture were -0.461 and -0.919, respectively. Mean of Z-scores of femoral neck BMD in hip fracture and vertebral fracture were -0.994 and -0.361, respectively. All Z-scores were negative values, which means reduction of BMD compared to decade-matched controls. Z-scores of bone formation markers, such as bone-specific ALP, osteocalcin, and PIPC, were positive values in vertebral fracture, which means an increase against decade-matched controls, whereas those were negative values in hip fracture. Z-scores of bone resorption markers, such as deoxypyridinoline and CTX, were greater in hip fracture than in vertebral fracture. To express bone balance between formation and resorption in hip fracture and vertebral fracture, we calculated an uncoupling status index (USI) by the values of biochemical markers. USI of hip fracture showed a great negative value (-1.29), which indicates excess of bone resorption over formation, whereas that of vertebral fracture showed a small positive value (0.23). In conclusion, bone formation markers increase in vertebral fractures, but decrease in hip fracture. Bone resorption markers increase in both fracture, but greater increase in hip fracture.

Biochemical markers of bone turnover

BACKGROUND

Osteoporosis in many countries has reached epidemic proportions. This has stimulated the development of biochemical markers to assist in the assessment of osteoporotic risk and in monitoring the efficacy of treatment. Biochemical markers of bone turnover are products released from osteoblasts and osteoclasts or collagen breakdown products.

MARKERS

Markers of bone formation include bone-specific alkaline phosphatase (BAP), osteocalcin (OC) and procollagen peptides. All of these can be measured easily by immunoassay techniques. Of these markers, OC has been extensively studied. However, OC undergoes in vitro degradation, thus, assay results are variable. BAP, on the other hand, is much more stable and shows less within-person biological variation. Bone resorption markers include tartrate-resistant acid phosphatase (TRAP) and collagen breakdown products, such as pyridinium cross-links, galactosyl hydroxylysine and cross-linked telopeptides, such as CTx and NTx. Of these, deoxypyridinium (DPD) has been extensively studied. DPD shows diurnal variation and the within-individual biological variation is large. Of the newer assays, NTx appear to show large differences at menopause.

CONCLUSIONS

Thus, serum BAP and DPD or NTx are the current choice of bone markers.

Biochemical markers to survey bone turnover

Molecular markers of bone turnover have gained increasing relevance in the evaluation of patients with metabolic bone diseases. Their clinical applications include the assessment of future osteoporotic fracture risk, complementation of bone density measurements, diagnosis of certain metabolic osteopathies, therapeutic decision making, and monitoring of therapeutic efficacy and patient compliance. One should be aware, however, that the results from large epidemiologic or clinical trials are sometimes difficult to translate into the everyday clinical situation. The individual patient often has more than one disease that might affect either bone turnover or the handling of the parameters mentioned (or both). Analytic and biologic variability of bone markers can be significant and also needs to be considered when using these indices. In the scientific setting, conventional and new markers of bone turnover can help to elucidate formerly unknown mechanisms and pathways. Because the development of ever more specific and sensitive markers of bone metabolism is progressing rapidly, we are likely to witness new insights into the pathophysiology of bone diseases in the near future.

Biochemical markers of bone turnover. A look at laboratory tests that reflect bone status

Chemicals in serum and urine can serve as markers for monitoring bone loss, bone reformation, and the effectiveness of therapy in patients with osteoporosis. Although not yet well recognized or readily available, tests for these markers may prove preferable to densitometry in some settings or for some patients. In the future, biochemical markers may provide important information on fracture risks as well.

Vitamin D and bone mineral density

Bone mineral density (BMD) at the lumbar spine and the neck of femur and serum concentrations of 25-hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), alkaline phosphatase, calcium, albumin, creatinine and phosphate were measured in a group of 166 postmenopausal women (30-79 years) attending a bone clinic for bone density measurements. Four subjects with suspected primary hyperparathyroidism were excluded from analysis. BMD at the lumbar spine was correlated with body mass index (BMI) (r = 0.278, p = 0.0003), age (r = -0.194, p = 0.0134) and serum 25OHD (r = 0.188, p = 0.0167). BMD at the neck of femur correlated with BMI (r = 0.391, p < 0.0001), age (r = -0.356, p < 0.0001), PTH (r = -0.156, p = 0.047) and serum 25OHD (r = 0.231, p = 0.0031). Stepwise multiple regression analysis showed that age, BMI and serum 25OHD contributed to the variation in BMD at lumbar spine. At the neck of femur, PTH was an additional contributor. We conclude that serum 25OHD makes a contribution to BMD a lumbar spine and neck of femur.

Relationship of bone turnover to bone density and fractures

To assess the influence of bone turnover on bone density and fracture risk, we measured serum levels of osteocalcin (OC), bone alkaline phosphatase (BAP), and carboxy-terminal propeptide of type I procollagen (PICP), as well as 24-h urine levels of cross-linked N-telopeptides of type I collagen (NTx) and the free pyridinium cross-links, pyridinoline (Pyd) and deoxypyridinoline (Dpd), among 351 subjects recruited from an age-stratified random sample of Rochester, Minnesota women, PICP, NTx, and Dpd were negatively associated with age among the 138 premenopausal women. All of the biochemical markers were positively associated with age among the 213 postmenopausal women, and the prevalence of elevated turnover (> 1 standard deviation [SD] above the premenopausal mean) varied from 9% (PICP) to 42% (Pyd). After adjusting for age, most of the markers were negatively correlated with bone mineral density (BMD) of the hip, spine, or forearm as measured by dual-energy X-ray absorptiometry, and women with osteoporosis were more likely to have high bone turnover. A history of osteoporotic fractures of the hip, spine, or distal forearm was associated with reduced hip BMD and with elevated Pyd. After adjusting for lower BMD and increased bone resorption, reduced bone formation as assessed by OC was also associated with prior osteoporotic fractures. These data indicate that a substantial subset of elderly women has elevated bone turnover, which appears to adversely influence BMD and fracture risk. Combined biochemical and BMD screening may provide better prediction of future fracture risk than BMD alone.

Evaluation of bone turnover in postmenopause, vertebral fracture, and hip fracture using biochemical markers for bone formation and resorption

The purpose of this study is to evaluate bone turnover in postmenopausal status and established osteoporosis with vertebral fracture and hip fracture by assessing bone biochemical markers. Subjects were 50 healthy premenopausal subjects, 44 healthy postmenopausal subjects, 30 osteoporotic patients with vertebral fracture, and 31 osteoporotic patients with hip fracture. Alkaline phosphatase, osteocalcin, PICP, ICTP, NTx, free deoxypyridinoline, total pyridinoline and deoxypyridinoline were measured. In postmenopause, both Z-scores of bone formation markers and resorption markers were around 1-2. In osteoporosis, although Z-scores of bone formation markers were 0.4-2.8, resorption markers were 2.3-9.5. Moreover, Z-scores of resorption markers were higher in hip fracture than in vertebral fracture. These results indicate that bone formation and resorption increased and balanced in postmenopausal status. However, bone resorption increased more than bone formation and did not balance at all in osteoporosis. This imbalance is greater in hip fractures than in vertebral fractures.