The predictive role of bone turnover markers for BMD in middle-aged men

Could procollagen type I N-terminal propeptide (PINP) and bone alkaline phosphatase (B-ALP) be valid alternative diagnostic markers to dual X-ray absorptiometry (DEXA) in elderly females with osteoporosis? An Egyptian radiological and laboratory monocentric study

Background

Osteoporosis is a major health problem of elders. Dual X-ray absorptiometry (DEXA) is the commonly used modality for diagnosis osteoporosis; serum markers have been suggested for predicting osteoporosis and discriminate osteoporotic from healthy subjects. We aimed to analyze the status of some bone turnover biochemical markers namely PINP, B-ALP, estrogen, and progesterone in the elderly osteoporotic and osteopenic women as probable markers for the discrimination between patients and healthy individual in diagnosing osteoporosis, and also, to detect the impact of osteoporosis on quality of life of patients using assessment of the quality of life for osteoporosis (ECOS-16). Post-menopausal 108 females were involved in the current study, divided into two groups (osteoporotic group (60 with BMD˂-2.5), osteopenic group (48 with BMD between − 1 and − 2.5)), and 60 healthy elderly females as control group were involved in the study. Serum levels of procollagen type I N-terminal propeptide (PINP), bone alkaline phosphatase (B-ALP), estrogen, and progesterone were measured by ELISA technique.

Results

PINP and B-ALP significantly differ between studied groups. Also, PINP and B-ALP levels had high sensitivity and specificity to discriminate osteoporotic patients from healthy individuals. PINP and B-ALP significantly correlated with bone mineral density (BMD) and with ECOS-16. Estrogen differs significantly between osteoporotic and osteopenic groups and significantly correlated with bone mineral density of femur (BMD-F) and bone mineral density of spine (BMD-S) in the osteopenic group. Progesterone differed significantly between patients and controls and significantly correlated with BMD-F in the osteoporotic group.

Conclusion

We can consider PINP and B-ALP as biomarkers for early detection then monitoring of osteoporosis. Measuring these serum markers can replace the assessment of BMD if not available. Also, it could replace the gap between BMD subsequently spaced assessment or could be of value in cases with severe spondylosis, DISH syndrome, old spondylarthritis, and/or previous spinal surgery. Sex hormones could not differentiate the normal from the osteoporotic/osteopenic patients, so they cannot be used as diagnostic or prognostic markers. Validation of this assumption needs large and longitudinal studies.

Status of circulating bone turnover markers in elderly osteoporosis/osteopenia patients in comparison with healthy subjects

Background

In the aging individuals, osteoporosis is a major health problem. Due to the various limitations of dual X-ray absorptiometry (DEXA) for diagnosis osteoporosis, serum-based biochemical markers have been suggested for the discrimination between the patients and healthy subjects.

Objective

To investigate the serum levels of bone turnover markers in elderly osteoporosis patients.

Methods

The serum samples from elderly subjects (osteoporosis (n = 28), osteopenia (n = 28), and healthy ones (n = 28) were collected from Amirkola Health and Ageing Project study. Furthermore, serum levels of bone formation and bone resorption markers as well as estrogen and progesterone were measured by enzyme-linked immunosorbent assay. Kruskal–Wallis test and receiver operating characteristic curve analysis were used for statistical analysis using SPSS.

Results

Levels of bone alkaline phosphatase (B-ALP) and procollagen type I N-terminal propeptide (PINP) differed between groups (P = 0.003 and 0.009, respectively). Furthermore, PINP and B-ALP levels had the best area under the curve, sensitivity, and specificity for the discrimination between patients with osteoporosis and healthy individuals.

Conclusion

In conditions in which we are not able to assess the bone mineral density by DEXA, analysis of the B-ALP and PINP levels may be a helpful tool.

Heterogeneity of biological bone markers in idiopathic male osteoporosis

In men with idiopathic osteoporosis, histomorphometric studies reported both increased resorption and decreased remodeling. We aimed at examine bone remodeling in these patients by biological marker measurement. We compared pre-treatment carboxy-terminal cross-linking telopeptide of type I collagen (CTX) and bone alkaline phosphatase (bALP) levels in 49 men, mean age 59 ± 14 year, with idiopathic osteoporosis with fractures (40 patients) or osteoporosis diagnosed by densitometry (9 patients) with 50 age-matched controls. The influence of baseline remodeling level on alendronate efficacy was studied. Bone remodeling markers (CTX and bALP) did not significantly differ between patients and controls and were correlated in both groups. There was no correlation between these markers, vitamin D and PTH levels. Twenty-one patients underwent repeat densitometry after 1 year of alendronate (70 mg/week). Mean annual BMD increase, spine +4.1 ± 3.9%, and hip +1.5 ± 1.2% showed no correlation with baseline CTX. Bone remodeling is very heterogeneous and formation and resorption remain biologically coupled in both idiopathic male osteoporosis and controls. Baseline remodeling level does not affect the action of alendronate on BMD.

Dynamic bone quality: a noninvasive measure of bone's biomechanical property in osteoporosis

We describe a novel approach to characterize bone quality noninvasively, a measurement that quantifies aggregate shock-absorption capacity of load-bearing bones as a measure of mechanical structural integrity during exposure to real-time self-induced in vivo loading associated with heel strike. The outcome measure, damping factor, was estimated at 5 load-bearing anatomical sites: ankle, tibial tuberosity, femoral condyle, lower back (at 3rd lumbar vertebra), and upper back (7th thoracic vertebra) plus the forehead in 67 patients with postmenopausal osteoporosis with and without documented vertebral fractures. The damping value was significantly lower in patients with vertebral fractures compared with those without a fracture (range: -36% to -72%; median: -44%). In these women with osteoporosis, damping factor was able to discriminate between patients with and without vertebral fractures, whereas traditional measures of bone density and biomechanical measures obtained from bone geometry were not significantly different between the groups.

Bone resorption in stroke and institutionalized subjects

Stroke increases the risk of hip fracture on the affected side. Although bone is lost by 1 year, rapidity of onset and relationship with immobility are uncertain. Using the bone resorption marker urinary cross-linked N telopeptide of type I collagen (uNTx), we examined bone resorption in the first 4 weeks after stroke, relating uNTx with bone density and mobility in subjects over 60 years. Two separate control groups acted as comparators, healthy (HC) and institutionalized (IC) controls, the latter to control for the effects of institutionalization. uNTx, urinary calcium (both related to creatinine and log-transformed), heel bone mineral density (BMD), Tinetti scores, and Barthel scores for prestroke function were measured. Log uNTx/Cr was lower in males compared with females, but this difference was not evident in stroke or IC subjects. Log uNTx/Cr was inversely related with BMD in females from both control groups and in male stroke subjects. Tinetti scores were divided into tertiles and were lower in stroke than IC subjects (P < 0.01). Log uNTx/Cr was similar in stroke and IC subjects in the lowest Tinetti tertile. Log uNTx/Cr was higher in stroke subjects of both sexes in the lowest tertile compared with the higher two tertiles combined (P < 0.05) and higher in all tertiles compared with HC subjects (P < 0.05). Subjects with a prestroke Barthel index of < or = 17 had higher log uNTx/Cr compared with HCs. Log uCa/Cr was higher only in male stroke patients. Bone resorption in stroke starts early, and measures to reduce this are merited.

Cathepsin K predicts femoral neck bone mineral density change in nonosteoporotic peri- and early postmenopausal women

OBJECTIVE

Cathepsin K is a cysteine protease that plays an essential role in organic bone matrix degradation. The aim of our study was to seek correlation of serum cathepsin K levels and a change in bone mineral density (BMD) over a 3-year period in a population of healthy nonosteoporotic women. The secondary end points were the correlations of serum cathepsin K with cross-sectional BMD and with other serum bone turnover markers and age.

DESIGN

In 43 healthy women aged 42 to 57 years, blood samples for determination of cathepsin K, osteocalcin, bone alkaline phosphatase, C-terminal cross-linking telopeptide of type I collagen, osteoprotegerin, and nuclear factor kappaB ligand were collected at the time of the first BMD measurement. BMD measurements were repeated after 3 years.

RESULTS

We found a moderate negative correlation of serum cathepsin K levels with change in femoral neck BMD, but none with change in spinal BMD. There were no significant correlations between cross-sectional BMD of the spine or femoral neck and serum levels of cathepsin K. Serum levels of cathepsin K were not significantly correlated with any bone turnover markers studied or with age.

CONCLUSIONS

Serum cathepsin K does not seem to represent a surrogate for bone turnover markers used at present, but it might be useful as a predictor of cortical bone loss.

Atrial extracellular matrix remodelling in patients with atrial fibrillation

Atrial fibrillation (AF) is the most frequent clinical arrhythmia. Atrial fibrosis is an important factor in initiating and maintaining AF. However, the collagen turnover and its regulation in AF has not been completely elucidated. We tested the hypothesis that the extracellular matrix changes are more severe in patients with permanent AF in comparison with those in patients in sinus rhythm (SR). Intraoperative biopsies from the right atrial appendages (RAA) and free walls (RFW) from 24 patients with AF undergoing a mini-Maze procedure and 24 patients in SR were investigated with qualitative and quantitative immunofluorescent and Western blot analyses. As compared with SR, all patients with AF exhibited dysregulations in collagen type I and type III synthesis/degradation. Tissue inhibitors of metalloproteinases (TIMP2) was significantly enhanced only in RAA-AF. As compared with SR, collagen VI, matrix metalloproteinases MMP2, MMP9 and TIMP1 were significantly increased while TIMP3 and TIMP4 remained unchanged in all AF groups. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a newly discovered MMPs inhibitor, was elevated in RFW as compared to RAA-AF (P<0.05) and RFW-SR (P<0.05). The level of transforming growth factor (TGF)-β1 was higher in AF than SR. Smad2 and phosphorylated Smad2 showed an elevation in RFW-AF as compared to RFW-SR, RAA-AF, and RAA-SR groups (P<0.05). Conclusions: Atrial fibrosis in AF is characterized by severe alterations in collagen I and III synthesis/degradation associated with disturbed MMP/TIMP systems and increased levels of RECK. TGF-β1 contributes to atrial fibrosis via TGF-β1-Smad pathway by phospho-rylating Smad2. These processes culminate in accumulations of fibrillar and non-fibrillar collagens leading to excessive atrial fibrosis and maintainance of AF.

Advances in the diagnosis and treatment of osteoporosis

Although severely low bone density is relatively rare in the pediatric population, it can be a significant problem in many patients with chronic illness. As peak bone formation occurs during adolescence, it is crucial that pediatricians and other care providers for this patient population recognize the significance of attainment of adequate bone. Dietary intake of vitamin D and calcium should be optimized, and correction of underlying causes of poor bone density should occur whenever possible. Assessment of bone density is difficult, as each technology available has problems, and none of the technologies are well-associated with fracture risk in pediatric patients. Once diagnosis of severely low bone density is established, treatment options are limited and poorly studied. The benefits of bisphosphonate therapy appear to outweigh the risks in patients with low bone density and frequent fragility fractures, and it appears that most improvement with bisphosphonates occurs within the first 2 to 4 years. Evidence, however, is emerging that once off therapy, bone turnover remains decreased for at least several years. During that time, improvements in bone density are decreased. Many questions remain regarding duration of therapy with bisphosphonate therapy and the long-term effects on the children who receive this medication. Anabolic therapies may become important in the future, but there is currently extremely limited information regarding their use in pediatrics.