A cross-sectional study on biochemical parameters of bone turnover and vitamin d metabolites in healthy dutch children and young adults

AIM: To provide reference data of biochemical markers of bone turnover and vitamin D metabolites for children and young adults. METHODS: Blood samples were taken from 176 healthy Dutch children and young adults (age range 7.6-25.3 years) to assess serum calcium, alkaline phosphatase, inorganic phosphate, osteocalcin, collagen type I cross-linked N-telopeptide, N-terminal propeptide of type I procollagen, 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 levels. Cross-linked telopeptide of type I collagen and carboxy-terminal propeptide of type I procollagen were assessed in 286 subjects (age range 1.4-25.3 years). RESULTS: Calcium and vitamin D levels were independent of age. The peak concentrations for collagen type I cross-linked N-telopeptide, cross-linked telopeptide of type I collagen, carboxy-terminal propeptide of type I procollagen, N-terminal propeptide of type I procollagen, alkaline phosphatase, and osteocalcin were found during puberty, in girls approximately 2.5 years earlier than in boys. Strong correlations were found between the markers of bone turnover, while no correlation was found between the markers of bone turnover and bone mineral density measured by dual-energy X-ray absorptiometry. CONCLUSIONS: Single measurements of bone markers cannot predict bone density. Reference data according to gender, age, and Tanner stage are given which allow calculating standard deviation scores adjusted for age and gender.     

Hormone replacement therapy,calcium and vitamin D<Subscript>3</Subscript> versus calcium and vitamin D<Subscript>3</Subscript>alone decreases markers of cartilage and bone metabolism in rheumatoid arthritis: a randomized controlled trial [ISRCTN46523456]

This study aimed to evaluate the effects of hormone replacement therapy (HRT), known to prevent osteoporosis and fractures, on markers of bone and cartilage metabolism. Furthermore, we assessed whether changes in these markers corresponded to alterations in bone mineral density and radiographic joint destructions in postmenopausal women with rheumatoid arthritis. Eighty-eight women were randomized to receive HRT, calcium, and vitamin D3, or calcium and vitamin D3 alone, for 2 years. Bone turnover was studied by analyzing serum levels of C-terminal telopeptide fragments of type I collagen (CTX-I), C-terminal telopeptide of type I collagen (ICTP), bone sialoprotein, and C-terminal propeptide of type I procollagen (PICP) and cartilage turnover by urinary levels of collagen type II C-telopeptide degradation fragments (CTX-II) and cartilage oligomeric matrix protein (COMP) in serum. Treatment with HRT resulted in decrease in CTX-I (P < 0.001), ICTP (P < 0.001), PICP (P < 0.05), COMP (P < 0.01), and CTX-II (P < 0.05) at 2 years. Reductions in CTX-I, ICTP, and PICP were associated with improved bone mineral density. Of the markers tested, CTX-I reflected bone turnover most sensitively; it was reduced by 53 +/- 6% in the patients receiving HRT. Baseline ICTP (P < 0.001), CTX-II (P < 0.01), and COMP (P < 0.05) correlated with the Larsen score. We suggest that biochemical markers of bone and cartilage turnover may provide a useful tool for assessing novel treatment modalities in arthritis, concerning both joint protection and prevention of osteoporosis.     

Low bone turnover in premenopausal women with type 2 diabetes mellitus as an early process of diabetes-associated bone alterations: a cross-sectional study

Background

Individuals with Diabetes Mellitus (DM) are at increased risk for fracture due to the decrease in bone strength and quality. Serum procollagen type I intact N-terminal (P1NP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX) as markers of bone formation and resorption, respectively, have been reported to be decreased in T2DM. It remains unclear whether diabetes-associated alterations in the bone turnover of T2DM individuals are related to the longer duration of the disease or may occur earlier. Furthermore, previous studies on BTMs in T2DM individuals have mostly been done in postmenopausal women with T2DM, which might have masked the DM-induced alterations of bone turnover with concurrent estrogen deficiency. This study aims to assess the levels of serum P1NP and CTX as markers of bone turnover in premenopausal women with and without T2DM.

Methods

This cross-sectional study involves 41 premenopausal women with T2DM, and 40 premenopausal women without DM. Sampling was done consecutively. P1NP and CTX measurement was done using the electrochemi-luminescence immunoassay (ECLIA) method. Other data collected include levels of HbA1C, ALT, creatinine, eGFR and lipid profile.

Results

Median (interquartile range) P1NP in T2DM is 29.9 ng/ml (24.7–41.8 ng/ml), while in non-DM is 37.3 ng/ml, (30.8–47.3 ng/ml; p?=?0.007). Median (interquartile range) CTX in T2DM is 0.161 ng/ml (0.106–0.227 ng/ml), while in non-DM is 0.202 ng/ml (0.166–0.271 ng/ml; p?=?0.0035). Levels of P1NP and CTX in the T2DM group did not correlate with the duration of disease, age, BMI or the levels of HbA1C.

Conclusions

Premenopausal women with T2DM indeed have lower bone turnover when compared with non-DM controls. This significantly lower bone turnover process starts relatively early in the premenopausal age, independent of the duration of DM. Gaining understanding of the early pathophysiology of altered bone turnover may be key in developing preventive strategies for diabetoporosis.

     

Biomarkers for osteoporosis management: utility in diagnosis, fracture risk prediction and therapy monitoring

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue, resulting in an increased risk of fracture. While the level of bone mass can be estimated by measuring bone mineral density (BMD) using dual X-ray absorptiometry (DXA), its measurement does not capture all the risk factors for fracture. Quantitative changes in skeletal turnover can be assessed easily and non-invasively by the measurement of serum and urinary biochemical markers; the most sensitive markers include serum osteocalcin, bone specific alkaline phosphatase, the N-terminal propeptide of type I collagen for bone formation, and the crosslinked C- (CTX) and N- (NTX) telopeptides of type I collagen for bone resorption. Advances in our knowledge of bone matrix biochemistry, most notably of post-translational modifications in type I collagen, are likely to lead to the development of new biochemical markers that reflect changes in the material property of bone, an important determinant of bone strength. Among those, the measurement of the urinary ratio of native (alpha) to isomerized (beta) CTX - an index of bone matrix maturation - has been shown to be predictive of fracture risk independently of BMD and bone turnover.In postmenopausal osteoporosis, levels of bone resorption markers above the upper limit of the premenopausal range are associated with an increased risk of hip, vertebral, and nonvertebral fracture, independent of BMD. Therefore, the combined use of BMD measurement and biochemical markers is helpful in risk assessment, especially in those women who are not identified as at risk by BMD measurement alone. Levels of bone markers decrease rapidly with antiresorptive therapies, and the levels reached after 3-6 months of therapy have been shown to be more strongly associated with fracture outcome than changes in BMD. Preliminary studies indicate that monitoring changes of bone formation markers could also be useful to monitor anabolic therapies, including intermittent parathyroid hormone administration and, possibly, to improve adherence to treatment. Thus, repeated measurements of bone markers during therapy may help improve the management of osteoporosis in patients.     

Long-Term Bioavailability of Single Doses of Intramuscular Vitamin D2

Objective: We sought to determine the long-term bioavailability of single doses of intramuscular (IM) vita-min D₂ (D₂) in healthy adults.Methods: Forty healthy volunteers with hypovitaminosis D received a single dose of 200,000, 400,000, or 600,000 IU intramuscular D₂ or no treatment. Levels of 25-hydroxyvitamin D₂ (25&lsqb;OH]D₂) and 25-hydroxyvitamin D₃ (25&lsqb;OH]D₃) in serum were measured by liquid chromatography-tandem mass spectrometry. Vitamin D binding protein (DBP) and intact parathyroid hormone (iPTH), bone turnover markers (BTMs), and serum and urinary calcium were also measured.Results: After a single dose of D₂ injection, the level of 25(OH)D₂ increased slowly and reached a plateau at 8 weeks. The plateau remained stable for 12 weeks. The mean increase in 25(OH)D₂ was 6.8, 9.6, or 15.6 ng/mL after injection of 200,000 IU, 400,000 IU, or 600,000 IU D₂. Although endogenous 25(OH)D₃ levels were reduced by IM D₂, the total 25(OH)D levels increased by 5.0, 7.0, or 10.3 ng/mL in average after injection of 200,000 IU, 400,000 IU, or 600,000 IU D₂. The iPTH levels were also decreased by IM D₂. However, levels of serum calcium, BTMs, and DBP and urinary calcium were not altered by IM D₂.Conclusion: A single dose of 200,000 IU, 400,000 IU, or 600,000 IU IM D₂ raises total 25-hydroxyvitamin D levels by 5.0, 7.0, or 10.3 ng/mL on average for at least 12 weeks and reduces iPTH and endogenous 25(OH)D₃ levels without affecting levels of serum calcium, BTMs, DBP, and urinary calcium.     

Adamts1 is highly induced in rachitic bones of FGF23 transgenic mice and participates in degradation of non-mineralized bone matrix collagen

Transgenic mice overexpressing fibroblast growth factor 23 (FGF23) in osteoblasts have a rachitic bone phenotype. These mice display hypomineralized bones, increased expression of osteoblast markers, but osteoclast numbers are unaltered or slightly reduced. Paradoxically, they show increased serum levels of the bone resorption marker CTX, a type I collagen degradation fragment. Here we analyzed a matrix metalloproteinase- (MMP-) like secreted protease, Adamts1, that has previously been associated with osteoblastic type I collagen breakdown in vitro. Bones from FGF23 transgenic (tg) mice displayed increased Adamts1 protein upon both immunohistological staining and Western blotting. We further found Adamts1 protein together with excessively degraded type I collagen in the non-mineralized bone fraction of FGF23 tg mice. A similar degradation pattern of type I collagen was noticed upon forced expression of Adamts1 in osteoblastic cells in vitro. Importantly, these Adamts1-expressing osteoblastic cells exhibited increased release of CTX fragments when cultured on demineralized bone discs. Together, these results demonstrate for the first time that Adamts1 can be highly induced in bone tissue and that this MMP-like protease can increase osteoblastic release of CTX fragments from non-mineralized bone. Thus, Adamts1 potentially contributes to the increased serum levels of CTX in rickets/osteomalacia.     

Characteristics of bone tissue metabolism in adolescents with undifferentiated connective tissue dysplasia

Biochemical markers of bone metabolism, including osteocalcin, total aminoterminal propeptide type I collagen (PINP), and the product of degradation of carboxy-terminal telopeptide type I collagen (β-CrossLaps) were studied in 17 adolescents 11–14 years of age with undifferentiated connective tissue dysplasia (UDCT). Decreased serum concentrations of bone formation markers (PINP and osteocalcin) against the background of normal levels of the bone resorption marker (β-CrossLaps) indicated that the processes of bone remodeling were disturbed and characterized by low-intensity bone-tissue formation with the relative predominance of resorption. The detected bone metabolism disturbances contributed to the development of osteopenia, which gives us grounds to include adolescents with UDCT to the risk group for early-onset osteoporosis.     

Allogeneic hematopoietic stem cell transplantation for acute leukemia with Gilbert's syndrome

The matrix protein osteopontin has been shown to be a marker of osteoclastic activity in multiple myeloma patients, as well as a regulator of angiogenesis. We measured serum levels of osteopontin in 50 untreated multiple myeloma patients (in 25, also after treatment) and examined the relation to markers of osteolytic and angiogenic activity. The median (range) of serum osteopontin was 85 (5-232) in the patient group vs. 36 (2-190) ng/ml in the control group. Serum osteopontin levels were significantly higher in patients with advanced stage or grade of myeloma disease. All patients with serum osteopontin levels >100 ng/ml had advanced stage (II or III) or high grade bone disease, whereas stage I or low grade patients had serum osteopontin levels <100ng/ml. Serum osteopontin levels significantly decreased after treatment. There was a positive correlation of osteopontin with the bone turnover marker N-terminal propeptide of procollagen type I (NTx) and the angiogenic markers vascular endothelial growth factor (VEGF) and bone marrow microvessel density (r: 0.35, 0.47 and 0.30 respectively, p < 0.05). These results support osteopontin as a dual marker of bone destruction and angiogenic activity in myeloma patients. Osteopontin represents a useful biomarker for monitoring myeloma disease activity.     

Comparison of bone metabolic markers between maternal and cord blood

We studied 41 normal pregnant women and their neonates in order to compare bone metabolism between them. We examined more specific bone formation markers (intact osteocalcin, bone-specific alkaline phosphatase) and a recently developed and more sensitive bone resorption marker (C-telopeptide of type I collagen; CTX) than previously available in maternal and umbilical cord venous blood taken at delivery. The concentrations of all markers of bone turnover, including CTX, in cord serum were significantly higher than those in maternal serum. There was no significant correlation between maternal and cord serum levels for any marker. These results indicate that fetal bone turnover is markedly enhanced compared with maternal bone turnover and is independent of maternal bone metabolism in late pregnancy.     

Does Baseline PTH Influence Recovery of Bone Mineral Density,Trabecular Bone Score and Bone Turnover Markers? A Prospective Study Following Curative PArathyroidectomy in Primary Hyperparathyroidism

Objective: This prospective study was carried out to assess trabecular bone score, bone mineral density (BMD), and bone biochemistry in Indian subjects with symptomatic primary hyperparathyroidism (PHPT), and to study the influence of baseline parathyroid hormone (PTH) on recovery of these parameters following curative surgery.Methods: This was a 2-year prospective study conducted at a tertiary care centre in southern India. Baseline assessment included demographic details, mode of presentation, bone mineral biochemistry, BMD, trabecular bone score (TBS), and bone turnover markers (BTMs). These parameters were reassessed at the end of the first and second years following curative parathyroid surgery.Results: Fifty-one subjects (32 men and 19 women) with PHPT who had undergone curative parathyroidectomy were included in this study. The mean (SD) age was 44.6 (13.7) years. The TBS, BTMs, and BMD at lumbar spine and forearm were significantly worse at baseline in subjects with higher baseline PTH (≥250 pg/mL) when compared to the group with lower baseline PTH (<250 pg/mL). At the end of 2 years, the difference between high versus low PTH groups (mean ± SD) persisted only for forearm BMD (0.638 ± 0.093 versus 0.698 ± 0.041 g/cm²; P =.01). However, on follow-up visits in the first and second year after curative parathyroidectomy, there was no significant difference in BTMs, BMD at the femoral neck, lumbar spine, and TBS between the 2 groups stratified by baseline PTH.Conclusion: The BMD at the forearm remained significantly worse in individuals with high baseline PTH even at 2 years after surgery, while other parameters including TBS improved significantly from baseline.Abbreviations: 25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; BMI = body mass index; BTMs = Bone turnover markers; CTX = C-terminal telopeptide of type 1 collagen; DXA = dual energy X-ray absorptiometry; P1NP = N-terminal propeptide of type 1 procollagen; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; TBS = trabecular bone score     

Effects of growth hormone replacement therapy on bone markers and bone mineral density in growth hormone-deficient adults

During the 1990s, interest in the effects of growth hormone deficiency (GHD) in adults increased, and several studies were performed to evaluate the effects of growth hormone (GH) substitution therapy in these patients. Because adults with GHD have reduced bone mineral density (BMD) and an increased risk of fractures, the effects of GH replacement therapy on bone metabolism have been evaluated in long-term studies. A universal finding is that the serum and urinary levels of biochemical bone markers increase during GH substitution therapy, and these increases are dose dependent. After years of GH substitution therapy, the levels of biochemical bone markers remain elevated, according to some studies, whereas other studies report that these levels return to baseline. BMD of the spine, hip and forearm increase after 18-24 months of treatment. Bone mineral content (BMC) increases to a greater extent than BMD, because the areal projection of bone also increases. This difference could be caused by increased periosteal bone formation, but a measurement artefact resulting from the use of dual-energy X-ray absorptiometry cannot be excluded as a possible explanation. One study of GH-deficient adults found that, after 33 months of GH treatment, BMD and BMC increased to a greater extent in men with GHD than in women. There is also a gender difference in the increases in serum levels of insulin-like growth factor I and biochemical bone markers during GH treatment. The reason for these findings is unknown, and the role of sex steroids in determining the response to GH therapy remains to be fully elucidated.     

Serum BAP as the clinically useful marker for predicting BMD reduction in diabetic hemodialysis patients with low PTH

With decrease of serum PTH in hemodialysis (HD) patients, other factors besides parathyroid hormone (PTH) become important in regulating bone metabolism. We investigated which serum bone metabolic marker is the best to predict the bone mineral density (BMD) reduction in HD patients with serum PTH<180 pg/ml. The bone formation markers, bone alkaline phosphatase (BAP), intact osteocalcin (OC), and N-terminal propeptide of type I collagen (PINP), and the bone resorption markers, deoxypyridinoline (DPD), pyridinoline (PYD), and beta-crossLaps (beta-CTx) were measured in serum from 137 HD patients. BMD of all patients was measured twice, approximately 1.5 years before and 1.5 years after measurement of their markers of bone metabolism. In all 137 HD patients, serum BAP was the only marker significantly higher in those with BMD reduction than in those without. In 42 diabetes mellitus (DM) HD patients with serum PTH<180 pg/ml, hypothetically low bone turnover state, serum BAP was again the only marker to discriminate those with BMD reduction from those without. At serum PTH<60 pg/ml, serum BAP retained tendency toward higher value. These findings suggest that serum BAP might be the most sensitive to identify small changes of bone metabolism in low bone turnover state. Retrospective study confirmed the usefulness of serum BAP in clinical practice by significantly higher values in those with bone loss at PTH<180 pg/ml even in under routine sample handling. In conclusion, serum BAP is a clinically useful bone formation marker to predict the BMD reduction in DM HD patients with low level of PTH.     

Inhibition of PPARgamma prevents type I diabetic bone marrow adiposity but not bone loss

Diabetes type I is associated with bone loss and increased bone adiposity. Osteoblasts and adipocytes are both derived from mesenchymal stem cells located in the bone marrow, therefore we hypothesized that if we could block adipocyte differentiation we might prevent bone loss in diabetic mice. Control and insulin-deficient diabetic BALB/c mice were chronically treated with a peroxisomal proliferator-activated receptor gamma (PPARgamma) antagonist, bisphenol-A-diglycidyl ether (BADGE), to block adipocyte differentiation. Effects on bone density, adiposity, and gene expression were measured. BADGE treatment did not prevent diabetes-associated hyperglycemia or weight loss, but did prevent diabetes-induced hyperlipidemia and effectively blocked diabetes type I-induced bone adiposity. Despite this, BADGE treatment did not prevent diabetes type I suppression of osteoblast markers (runx2 and osteocalcin) and bone loss (as determined by micro-computed tomography). BADGE did not suppress osteoblast gene expression or bone mineral density in control mice, however, chronic (but not acute) BADGE treatment did suppress osteocalcin expression in osteoblasts in vitro. Taken together, our findings suggest that BADGE treatment is an effective approach to reduce serum triglyceride and free fatty acid levels as well as bone adiposity associated with type I diabetes. The inability of BADGE treatment to prevent bone loss in diabetic mice suggests that marrow adiposity is not linked to bone density status in type I diabetes, but we cannot exclude the possibility of additional BADGE effects on osteoblasts or other bone cells, which could contribute to preventing the rescue of the bone phenotype.     

Biomarkers of bone healing induced by a regenerative approach based on expanded bone marrow–derived mesenchymal stromal cells

BackgroundSafety and feasibility of a regenerative strategy based on the use of culture-expanded mesenchymal stromal cells (MSCs) have been investigated in phase 2 trials for the treatment of nonunion and osteonecrosis of the femoral head (ONFH). As part of the clinical study, we aimed to evaluate if bone turnover markers (BTMs) could be useful for predicting the regenerative ability of the cell therapy product.Materials and MethodsThe bone defects of 39 patients (nonunion: n = 26; ONFH: n = 13) were treated with bone marrow–derived MSCs, expanded using a clinical-grade protocol and combined with biphasic calcium phosphate before implantation. Bone formation markers, bone-resorption markers and osteoclast regulatory proteins were measured before treatment (baseline) and after 12 and 24 weeks from surgery. At the same time-points, clinical and radiological controls were performed to evaluate the bone-healing progression.ResultsWe found that C-Propeptide of Type I Procollagen (CICP) and C-terminal telopeptide of type-I collagen (CTX) varied significantly, not only over time, but also according to clinical results. In patients with a good outcome, CICP increased and CTX decreased, and this trend was observed in both nonunion and ONFH. Moreover, collagen biomarkers were able to discriminate healed patients from non-responsive patients with a good diagnostic accuracy.DiscussionCICP and CTX could be valuable biomarkers for monitoring and predicting the regenerative ability of cell products used to stimulate the repair of refractory bone diseases. To be translated in a clinical setting, these results are under validation in a currently ongoing phase 3 clinical trial.     

The luteinising hormone-releasing hormone analogue triptorelin with or without the aromatase inhibitor formestane in premenopausal breast cancer: effects on bone metabolism markers

BACKGROUND: the combination of a luteinising hormone-releasing hormone (LH-RH) analogue and an aromatase inhibitor (AI) induces greater oestrogen suppression than the analogue alone in premenopausal breast cancer. However, very few data on the biological effects of such a combination are currently available. AIM OF THE STUDY: the short-term effects of treatment with the LH-RH analogue triptorelin alone or in association with the AI formestane on bone metabolism were investigated in premenopausal breast cancer. Circulating levels of the bone formation markers carboxy-terminal and amino-terminal propeptides of type I procollagen (PICP and PINP) and the bone resorption marker cross-linked carboxy-terminal telopeptide of type I collagen (ICTP) were assessed. In addition, serum levels of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and interleukin 6 (IL-6) were evaluated. PATIENTS AND METHODS: twenty-one patients with advanced breast cancer were randomly given triptorelin monthly alone (n=10, arm A) or in combination with formestane fortnightly (n=11, arm B). Blood samples were collected over a 3-month period. RESULTS: serum PICP and PINP levels increased significantly over time (P=0.0065 and 0.0197 in arm A and B, respectively); no change in ICTP levels was observed. A rise in IGF-I and IGFBP-3 levels was seen in each treatment group, but only the increase in IGF-I was significant (P=0.0138, always). The on-treatment levels of the bone turnover markers and IGF-system components were inversely correlated with serum oestrogens. Neither treatment modalities significantly affected serum IL-6 levels over time. No difference in the behaviour of any of the assessed biomarkers was observed between patients with or without skeletal metastases. CONCLUSION: it is worth noting that complete oestrogen depletion, at least in our case series, seems to increase only osteoblastic activity markers. The observed modifications appear to be related to oestrogen depletion per se rather than the degree of oestrogen suppression or the different therapeutic regimen administered.     

Combined Oral Administration of Bovine Collagen Peptides with Calcium Citrate Inhibits Bone Loss in Ovariectomized Rats

Purpose

Collagen peptides (CPs) and calcium citrate are commonly used as bone health supplements for treating osteoporosis. However, it remains unknown whether the combination of oral bovine CPs with calcium citrate is more effective than administration of either agent alone.

Methods

Forty 12-week-old Sprague-Dawley rats were randomly divided into five groups (n = 8) for once-daily intragastric administration of different treatments for 3 months at 3 months after ovariectomy (OVX) as follows: sham + vehicle; OVX + vehicle; OVX + 750 mg/kg CP; OVX + CP-calcium citrate (75 mg/kg); OVX + calcium citrate (75 mg/kg). After euthanasia, the femurs were removed and analyzed by dual energy X-ray absorptiometry and micro-computed tomography, and serum samples were analyzed for bone metabolic markers.

Results

OVX rats supplemented with CPs or CP-calcium citrate showed osteoprotective effects, with reductions in the OVX-induced decreases in their femoral bone mineral density. Moreover, CP-calcium citrate prevented trabecular bone loss, improved the microarchitecture of the distal femur, and significantly inhibited bone loss with increased bone volume, connectivity density, and trabecular number compared with OVX control rats. CP or CP-calcium citrate administration significantly increased serum procollagen type I N-terminal propeptide levels and reduced serum bone-specific alkaline phosphatase, osteocalcin, and C-telopeptide of type I collagen levels.

Conclusions

Our data indicate that combined oral administration of bovine CPs with calcium citrate inhibits bone loss in OVX rats. The present findings suggest that combined oral administration of bovine CPs with calcium citrate is a promising alternative for reducing bone loss in osteopenic postmenopausal women.     

Combining information from multiple bone turnover markers as diagnostic indices for osteoporosis using support vector machines

Context: Osteoporosis (OP) is a progressive systemic bone disease. Dual-energy X-ray absorptiometry (DXA) is routinely employed and is considered the gold standard method for the diagnosis of OP.

Objective: We aimed to investigate the potential use of combined information from multiple bone turnover markers (BTMs) as a clinical diagnostic tool for OP.

Materials and methods: A total of 9053 Chinese postmenopausal women (2464 primary OP patients and 6589 healthy controls) were recruited. Serum levels of six common BTMs, including BAP, BSP, CTX, OPG, OST and sRANKL were assayed. Models based on support vector machine (SVM) were constructed to explore the efficiency of different combinations of multiple BTMs for OP diagnosis.

Results: Increasing the number of BTMs used in generating the models increased the predictive power of the SVM models for determining the disease status of study subjects. The highest kappa coefficient for the model with one BTM (BAP) compared to DXA was 0.7783. The full model incorporating all six BTMs resulted in a high kappa coefficient of 0.9786.

Conclusion: Our findings showed that although single BTMs were not sufficient for OP diagnosis, appropriate combinations of multiple BTMs incorporated into the SVM models showed almost perfect agreement with the DXA.     

Analysis of bone mineral density and turnover in patients with cystic fibrosis: associations between the IGF system and inflammatory cytokines

BACKGROUND: Cystic fibrosis (CF) patients present an increased risk of osteoporosis, and increased fracture rate. Several factors have been identified as modulators of bone metabolism and bone mineral density (BMD). AIMS: To evaluate BMD and serum markers of bone turnover and establish their relationships with serum concentrations of interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha, IGF-I, IGF-II, IGF binding protein (IGFBP)-2, IGFBP-3, and parathyroid hormone (PTH) in young adult CF patients. METHODS: Seventeen young adult CF patients (4 M, 13 F; mean age: 26.6 +/- 1.1 years) were enrolled in the study and analysed as a whole and as two subgroups according to the Shwachman-Kulczycki score. BMD was assessed at the lumbar spine (L1-L4) by dual energy X-ray absorptiometry (DXA Hologic QDR 2000). Bone turnover was assessed by measuring serum levels of osteocalcin (OC) and serum carboxyterminal propeptide of type I collagen (PICP) as markers of bone formation, and serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) as a marker of bone resorption. Serum IGFs, IGFBPs, and cytokines were assayed using special commercial kits. Daily calcium intake and weekly physical activity were estimated by questionnaires. Forced expiratory volume in one second was used to assess pulmonary function. RESULTS: Lumbar BMD was normal, although there was a tendency to be lower in the patients with a lower clinical score. Both OC and PICP were increased, whereas ICTP was normal. Lumbar BMD was positively correlated with pulmonary function. IL-6 and C-reactive protein (markers of inflammation) were inversely correlated with PICP. Serum ICTP levels were correlated with serum IGF-I levels.No significant relationship was detected among lumbar BMD, markers of bone turnover and PTH, IGF-I, IGF-II, IGFBP-2, IGFBP-3, TNF-alpha, IL-1beta, and body mass index Z-score. CONCLUSIONS: Bone turnover is abnormal in CF patients. Young adult CF patients with satisfying clinical status and nutritional conditions have normal BMD and increased serum OC and PICP levels.     

Relationships of serum leptin levels with biochemical markers of bone turnover and with growth factors in normal weight and overweight children

Objective: To examine the hypothesis of an influence of leptin on growth factors and on biochemical markers of bone turnover of prepubertal overweight children. Design and Methods: 395 prepubertal children, 6-13 years of age, were selected and the relationships between circulating serum levels of leptin and insulin-like growth factor I (IGF-I), insulin growth factor binding protein-3 (IGFBP-3) and some biochemical markers of bone turnover (osteocalcin, OC; carboxyterminal propeptide of type I procollagen, PICP, and carboxyterminal propeptide of type I collagen, ICTP) were analyzed. The subjects were subdivided into normal weight (NW, n = 163) and weight excess (WE, n = 232) subjects. Results and Conclusions: Significant differences between the two groups were found for leptin (p < 0.01), IGF-I (p < 0.01) and IGFBP-3 (p < 0.01), with higher values in WEs, and for OC (p < 0.01) with higher values in NWs. A significant reduction of leptin (p < 0.01) and IGFBP-3 (p < 0.01) serum values and an increase of those of OC (p < 0.01) and PICP (p < 0.05), but not of ICTP, were registered in 103 WEs who showed a drop in weight excess during a weight-excess reduction program. No variations were observed in 26 non-responsive subjects. In a multivariate analysis in which leptin, corrected by BMI and sex, was the independent variable, a significant negative correlation was found with PICP (beta = -0.235, p < 0.01), IGF-I (beta = -0.180, p < 0.01) and height velocity (beta = -0.155, p < 0.01). There was no correlation with OC, ICTP and IGFBP-3. The results demonstrate that nutritional status and leptin levels are involved in the regulation of growth factors and biochemical markers of bone formation.     

The Role of PINP in Diagnosis and Management of Metabolic Bone Disease

Serum procollagen type I N-propeptide (PINP) is designated the reference marker of bone formation in osteoporosis; the reference marker for resorption is C-terminal telopeptide of type I collagen (CTX). PINP has very low circadian and biological variation, is not affected by food intake, and is very stable in serum after venepuncture. The two automated commercial assays for PINP provide similar results in subjects with normal renal function, allowing reference intervals to be used interchangeably. Bone turnover markers (BTM) are currently not recommended for fracture risk assessment and therefore not included in fracture risk calculators. In the management of osteoporosis, the main utility of BTM including PINP is for monitoring therapy, both antiresorptive as well as anabolic agents; monitoring is thought to help improve adherence. PINP as well as CTX may also be used in assessing offset of drug action following a pause in bisphosphonate therapy, to help decide when to re-instate therapy, or following cessation of denosumab therapy to assess efficacy of follow-on bisphosphonate therapy. PINP may also be used in the diagnosis of Paget’s disease of bone as well as in monitoring response to therapy and for recurrence. Although BTM other than bone alkaline phosphatase are currently not recommended for use in metabolic bone disease of chronic kidney disease, PINP measured by assays specific to the intact molecule has potential in this condition. Further studies are needed to examine this area, as well as in malignant bone disease.