Monitoring individual response to hormone replacement therapy with bone markers

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.

Effects of High-Impact Weight-Bearing Exercise on Bone Mineral Density and Bone Metabolism in Middle-Aged Premenopausal Women: A Randomized Controlled Trial

This study examined the effects of high-impact weight-bearing exercise on bone mineral density (BMD) and bone metabolic markers in middle-aged premenopausal women. Forty middle-aged premenopausal women were initially enrolled, but thirty-one participants (40.34 ± 3.69 years) completed in the study. The subjects were randomly divided into two groups including the high-impact weight-bearing exercise group (HWE, n = 14) and control group (CON, n = 17). The HWE group participated in the exercise for 50 min a day, three days per week for four months, while the CON group maintained their regular lifestyle. The HWE program included 10 different high-impact weight-bearing exercises such as jumping and running. BMD was measured using DXA (Hologic, QDR 4500W, Marlborough, MA, USA). The bone metabolic markers including serum 25-(OH) D, intact parathyroid hormone (PTH), osteoprotegerin (OPG), osteopontin (OPN), receptor activator of nuclear factor κB ligand (RANKL), osteocalcin (OC), C-terminal telopeptide of type 1 collagen (CTX), and calcium were analyzed. The results showed that the BMDs of femur, lumbar, and forearm did not significantly change during the intervention period in both the HWE and CON groups. A significant decrease in bone formation markers such as OC (F = 10.514, p = 0.003, ηp2 = 0.266) and an increase in bone resorption marker including CTX (F = 8.768, p = 0.006, ηp2 = 0.232) were found only in the CON group, while these values did not change in the HWE group. There was a significant increase in serum 25-(OH) D (F = 4.451, p = 0.044, ηp2 = 0.133) in the HWE group. Our findings suggest that four months of HWE is not sufficient to improve BMD and bone metabolic markers, but this impact exercise program may prevent the age-associated changes in bone turnover markers in middle-aged premenopausal women.

Reference Intervals for Bone Turnover Markers in Korean Healthy Women

Background

Adequate suppression of bone turnover rate is important to decrease fracture risk without mineralization defect due to oversuppression. This study was performed to determine reference intervals (RIs) for 2 bone turnover markers, serum C-terminal telopeptide of type I collagen (CTX) and osteocalcin, in Korean women.

Methods

A total of 461 Korean women (287 premenopausal and 174 postmenopausal) without any disease or drug history affecting bone metabolism was included. Serum CTX and osteocalcin were measured after overnight fasting. Bone mineral density (BMD) was measured at the 1st to 4th lumbar vertebra using dual energy X-ray absorptiometry. Subjects with normal spinal BMD (T-score ≥-1.0) were included in this study.

Results

After stable concentrations were maintained, both CTX and osteocalcin were abruptly increased in 50 to 59 years, and then decreased with increasing age. Median levels and interquartile range of serum CTX and osteocalcin in all subjects were 0.322 (0.212-0.461) ng/mL and 15.68 (11.38-19.91) ng/mL. RIs for serum CTX and osteocalcin in all subjects were 0.115 to 0.861 ng/mL and 6.46 to 36.76 ng/mL. Those were higher in postmenopausal women (CTX, 0.124-1.020 ng/mL, osteocalcin, 5.42-41.57 ng/mL) than in premenopausal women (CTX, 0.101-0.632 ng/mL, osteocalcin, 6.73-24.27 ng/mL). If we use target reference levels as lower half of premenopausal 30 to 45 years in patients with antiresorptive drugs, those were 0.101 to 0.251 ng/mL and 6.40 to 13.36 ng/mL.

Conclusions

We established RIs for serum CTX and osteocalcin in healthy Korean women with normal lumbar spine BMD. Premenopausal RIs for serum CTX and osteocalcin would be useful to monitor patients with low bone mass using osteoporosis drugs.

Correlation between Bone Turnover Markers and Bone Mineral Density in Patients Undergoing Long-Term Anti-Osteoporosis Treatment: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to evaluate the correlations between the bone turnover markers (BTMs) and the bone mineral density (BMD) in patients treated for primary osteoporosis and to identify promising BTMs for the prediction of future BMD changes. The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for relevant studies that investigated the relationship between the BTMs and the BMD changes in patients treated for osteoporosis. All significant correlation coefficients of the baseline BTMs or changes in BTMs from baseline with the BMD changes from baseline under different interventions from eligible studies were used for systematic review and the subgroup analyses. The correlations were analyzed in terms of bone sites, intervention, time duration of BTMs measurements, and time duration of BMD measurements. Twenty-two records reporting correlation coefficients and the corresponding p-values were included, 13 of which were enrolled in the further subgroup analyses. The combined results from the systematic review and meta-analyses indicated that the changes in osteocalcin (OC), procollagen type I N propeptide (PINP), and urine N-terminal crosslinking telopeptide of type I collagen (U-NTX), or the PINP at baseline tended to be useful in evaluating the long-term BMD changes after drug intervention.

Executive summary of the Japan Osteoporosis Society Guide for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis (2018 Edition)

With the aging of society, the number of osteoporosis-related fractures is increasing. Prevention of osteoporosis and maintenance of the quality of life of osteoporosis patients require early diagnosis, effective treatment, and highly precise treatment monitoring. Although bone biopsy is clinically one of the essential techniques for diagnosis of osteoporosis, it is invasive and difficult to perform in general clinical practice. Bone mineral density measurement is another essential technique available in clinical practice that provides good precision. However, it is not effective for determining the appropriate treatment options or evaluating short-term treatment efficacy. On the other hand, bone turnover markers (BTMs) have gained attention because they provide information that is valuable for both the selection of treatment and short-term monitoring. BTMs are now positioned to become a tool for clinically assessing bone turnover outcomes. Since the Japan Osteoporosis Society issued its Guidelines for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis in 2012, new drugs, drug formulations, and combination drug therapies have been approved; therefore, we updated the 2012 guidelines in the Guide for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis (2018 Edition).

Analysis of Bone Alkaline Phosphatase as a Marker for the Diagnosis of Osteoporosis in Men under Androgen Ablation

The objective of this study was to evaluate the usefulness of serum determination of bone alkaline phosphatase (BAP) in the diagnosis of osteoporosis in men with prostate cancer under androgen ablation. Serum levels of BAP and bone mineral density (BMD) were assessed in 110 patients with non-metastatic, treated prostate cancer. Fifty-eight patients were under androgen deprivation during a period between two and 96 months and 52 had been submitted only to radical prostatectomy. Mean serum BAP was 11.8 ng/mL in patients with normal BMD, 16.7 ng/mL in patients with osteopenia (p. 0.058), and 19.3 ng/mL in patients with osteoporosis (p=0.044). The correlation between serum BAP and BMD was significant (p. 0.006) but with an index of only 0.26. Receiver operating characteristic analysis for the diagnosis of osteoporosis showed an area under the curve of 0.608. None of the cutoff points that provided specificities of 75%, 90% and 95% gave significant distributions. The positive and negative predictive values as well as the odds ratios were not of any clinical usefulness. We conclude that serum BAP should not be considered a good marker for the diagnosis of osteoporosis in men with prostate cancer. Therefore, BAP serum determination cannot replace bone densitometry as a diagnostic tool.

Osteocalcin as a potential risk biomarker for cardiovascular and metabolic diseases

Clear evidence supports a role for circulating and locally-produced osteocalcin (OC) in the pathophysiology of cardiovascular (CV) lesions and CV risk, also in combination with metabolic changes, including type 2 diabetes mellitus (T2DM). Reduced plasma OC levels are associated with greater incidence of pathological CV changes, like arterial and valvular calcification, coronary and carotid atherosclerosis and increased carotid intima-media thickness. The actual relationship between OC levels and incidence of major CV events is, however, still unclear. Moreover, reduced circulating OC levels have been mostly associated with insulin resistance, metabolic syndrome or T2DM, indicating relevant OC actions on pancreatic β-cells and insulin secretion and activity. Based on these observations, this review article will attempt to summarize the current evidence on the potential usefulness of circulating OC as a biomarker for CV and metabolic risk, also evaluating the currently open issues in this area of research.

Biochemical markers for assessment of calcium economy and bone metabolism: application in clinical trials from pharmaceutical agents to nutritional products

Nutrition plays an important role in osteoporosis prevention and treatment. Substantial progress in both laboratory analyses and clinical use of biochemical markers has modified the strategy of anti-osteoporotic drug development. The present review examines the use of biochemical markers in clinical research aimed at characterising the influence of foods or nutrients on bone metabolism. The two types of markers are: (i) specific hormonal factors related to bone; and (ii) bone turnover markers (BTM) that reflect bone cell metabolism. Of the former, vitamin D metabolites, parathyroid hormone, and insulin-like growth factor-I indicate responses to variations in the supply of bone-related nutrients, such as vitamin D, Ca, inorganic phosphate and protein. Thus modification in bone remodelling, the key process upon which both pharmaceutical agents and nutrients exert their anti-catabolic or anabolic actions, is revealed. Circulating BTM reflect either osteoclastic resorption or osteoblastic formation. Intervention with pharmacological agents showed that early changes in BTM predicted bone loss and subsequent osteoporotic fracture risk. New trials have documented the influence of nutrition on bone-tropic hormonal factors and BTM in adults, including situations of body-weight change, such as anorexia nervosa, and weight loss by obese subjects. In osteoporosis-prevention studies involving dietary manipulation, randomised cross-over trials are best suited to evaluate influences on bone metabolism, and insight into effects on bone metabolism may be gained within a relatively short time when biochemical markers are monitored.

Cathepsin K in treatment monitoring following intravenous zoledronic acid

Cathepsin K (CatK) is mainly expressed by osteoclasts and plays an important role in bone resorption. As CatK is expressed and secreted by osteoclasts during active bone resorption, it may be a useful and specific biochemical marker of osteoclastic activity. Therefore, CatK serum levels were studied for monitoring the treatment of females with postmenopausal osteoporosis by zoledronic acid. The serum CatK levels were determined in nine postmenopausal females before and after 3, 6 and 12 months of treatment. The levels were significantly reduced after 3 and 6 months (P<0.05), whereas they returned to baseline after 1 year. Taken together, the serum level of CatK may be suitable for monitoring anti-osteoporotic therapy in association with treatment response.

Bone turnover markers in patients with type 1 Gaucher disease

Bone complications occur frequently in Gaucher disease (GD) and reduce the quality of life of these patients. Skeletal involvement is an important indication for treatment to ameliorate symptoms and reduce the risk of irreversible and debilitating disease. Bone biomarkers have been used to assess disease status and the response to therapy in a number of bone disorders. Here, we examine the literature for evidence of abnormalities in bone turnover markers in patients with type 1 GD to assess whether they might be useful for the assessment of bone involvement in GD. We have found that bone biomarkers in GD show highly variable results which do not currently support their routine use for clinical assessment of bone status, as an indication for therapy initiation, or for monitoring the response to therapy. A greater understanding of bone markers and their relation to the bone manifestations of GD is required.

Reference intervals of bone turnover markers in healthy premenopausal women: results from a cross-sectional European study

Robust validated reference intervals for bone turnover markers (BTMs) are required to assess fracture risk and effectiveness of therapy. However, there are currently limited reference intervals for BTMs in premenopausal women, especially comparing manual and automated assays. This study determined the BTM reference intervals using automated and manual assays, compared the results obtained from two different assays, and evaluated the factors that may affect BTM levels. This was a cross-sectional registry study in 194 healthy, premenopausal, European Caucasian women aged 35 to 39years from France (n=98) and Denmark (n=96). Two independent specialized laboratories, one in France (Synarc) and the other in Denmark (Nordic Bioscience), analyzed blood and urine samples from each woman for BTM levels. The type of assay used in this study significantly affected the reference intervals obtained for serum cross-linked C-terminal telopeptide of type I collagen (sCTX) and urinary cross-linked N-terminal telopeptides of type I collagen (uNTX/Cr; both P<0.001), but not for serum procollagen type I amino-terminal propeptide (PINP; P=0.28). The Serum Crosslaps® ELISA; Microtitre-plate based ELISA; Metra BAP EIA; and UniQ® PINP RIA assays yielded higher BTM reference values. The reference intervals for the BTMs, as measured with Serum β-Crosslaps, Elecsys® 2010 Systems; VITROS® ECI System; Ostase®, Access® Immunoassay System; and Total PINP, Elecsys® 2010 Systems assays, were 0.111-0.791ng/mL for sCTX, 12.3-59.7nmol BCE/mmol creatinine for uNTX/Cr, 5.8-17.5ng/mL for bone alkaline phosphatase (ALP), and 17.3-83.4ng/mL for PINP, respectively. When measured with Serum Crosslaps® ELISA, Microtitre-plate based ELISA, Metra BAP EIA, and UniQ® PINP RIA, the reference intervals were 0.177-0.862ng/mL for sCTX, 22.6-95.7nmol BCE/mmol creatinine for uNTX/Cr, 14.8-38.8U/L for bone ALP, and 19.5-75.2ng/mL for PINP, respectively. The clinical interpretation of the BTMs of a subject should be based on comparison with a BTM reference interval, measured with the same assay method.

Responses of urinary N-telopeptide and renal calcium handling to PTH infusion after treatment with estrogen, raloxifene, and tamoxifen

This prospective, randomized, placebo-controlled study investigated whether estrogen, tamoxifen, and raloxifene protect the skeleton from the acute catabolic effects of continuous PTH(1-34) infusion. It was infused over 24 h in 25 postmenopausal women both before and while on medication for 16-20 weeks (estrogen n = 7, raloxifene n = 5, tamoxifen n = 7, placebo n = 6). Blood and urine samples were collected at baseline and every 4 h during the PTH(1-34) infusion and analyzed for calcium homeostasis, bone remodeling, and specific cytokines. Data for the premedication PTH(1-34) infusions were pooled. During the premedication PTH(1-34) infusions, serum calcium and urine phosphorus increased, while serum phosphorus and urine calcium declined. Osteocalcin decreased (mean 18%), while urine NTX increased (mean 315%). Serum IL-6 increased 260%, but there were no other cytokine changes as a result of the PTH(1-34) infusion. On medication, the mean peak change in NTX with PTH(1-34) infusion was less (77, 59, and 31 nM/mM with raloxifene, tamoxifen, and estrogen, respectively). The reduction in urine calcium excretion was prolonged with each agent but only significantly with estrogen. There was no reduction in the IL-6 elevation induced by PTH(1-34) with any medication. The differential skeletal resorption response to PTH(1-34) infusion after the treatments may reflect different potencies of these agents or variability in interaction with the estrogen receptor. Renal calcium conservation and the blunted response of bone resorption to PTH(1-34) infusion may be mechanisms by which estrogen and estrogen agonist/antagonist agents preserve bone mass.

An old friend in a new light: the role of osteocalcin in energy metabolism

Accumulating evidence suggests interactions between bone and energy metabolism, which may affect the risk of cardiovascular disease. Recent animal studies indicate that osteocalcin (OC) plays a key role in the coordinated regulation of glucose and insulin metabolism while insulin receptors on osteoblasts may regulate bone turnover and circulating OC levels. Association studies, weight loss interventions, and observational data lend some support to the existence and relevance of these mechanisms in humans. However, corroborating evidence from pharmacologic interventions in either bone or glucose metabolism is limited by the number, design, and complex pharmacological effects of the drugs used. Furthermore, such clinical trials are complicated by the alteration of metabolic feedback mechanisms in the insulin resistant state. Purpose-designed studies are needed to further establish the existence and significance of the role of OC and its subfractions in human insulin metabolism. In this review we summarize existing animal evidence regarding the role of OC and its subfractions in bone and energy metabolism and assess current clinical trial evidence relating to the significance and consequences of this relationship in humans.

Bone turnover markers and bone mineral density response with risedronate therapy: relationship with fracture risk and patient adherence

Surrogate markers of fracture risk--bone turnover markers (BTMs) and bone mineral density (BMD)--can be used to monitor treatment response. We assessed whether changes in these markers greater than the least significant change (LSC) were associated with fracture risk reduction and greater adherence. This secondary analysis of the Improving Measurements of Persistence on ACtonel Treatment (IMPACT) study--a multinational prospective, open-label, cluster-randomized study of postmenopausal women on oral risedronate 5 mg/d for 52 weeks-assessed adherence by electronic monitors. Urinary N-terminal cross-linked telopeptide of type 1 collagen (uNTX) and serum C-terminal cross-linked telopeptide of type 1 collagen (sCTX) levels were assessed at baseline and weeks 10 and 22, and BMD at baseline and week 52. Fractures were recorded as adverse events. In 2302 women, responses beyond LSC in BTMs (uNTX and sCTX) and BMD (spine only) were associated with a reduced risk of nonvertebral fractures (NVFs) and all fractures. NVF incidence was about 50% lower in patients with 30% or more of uNTX reduction at week 22 (1.6%) than in those with less than 30% reduction (3.2%, p = .015). NVFs also were reduced in patients with more than 3% spine BMD increase at 52 weeks than those with 3% or less. Responses greater than LSC in BTMs and BMD were associated with greater adherence, but there was no association between adherence and fracture outcomes at 52 weeks. Changes greater than the LSC in BTMs and BMD reflect better treatment adherence, were associated with fracture risk reduction, and identify differences in individual responsiveness to risedronate.

Reference intervals of biochemical bone turnover markers for Saudi Arabian women: a cross-sectional study

Biochemical bone turnover markers (BTMs) provide important information on the diagnosis, therapy and monitoring of metabolic bone diseases including osteoporosis. One goal of antiresorptive therapy in women is to decrease biochemical BTMs to the lower half of reference intervals for healthy pre-menopausal counterparts, using newly developed automated assays of such markers. The main objectives of the present study were to: (1) establish reference interval values for the following biochemical BTMs: serum osteocalcine (s-OC), bone alkaline phosphatase (s-bone ALP), procollagen type 1 N-terminal propeptide (s-PINP), crosslinked C-terminal telopeptide of Type 1 collagen (s-CTX), tartarate-resistant acid phosphatase isoform 5b (s-TRACP-5b) and urinary: CTX (u-CTX), N-telopeptides of type 1 collagen (u-NTX), pyridinoline (u-PYD) and deoxypyridinoline (u-DPD) in randomly selected Saudi healthy pre-menopausal women; (2) study the changes in biochemical BTMs in relation to age in pre- and post-menopausal women and the factors reported to influence bone turnover and (3) determine the effect of menopausal status on BTMs. A total of 2125 women were studied [including (n=1557) pre-, and (n=568) post-menopausal women, respectively, aged 20-79 years]. A total of 765 healthy pre-menopausal women (aged 35-45 years) were used to establish reference intervals for biochemical BTMs. All women studied were medically examined and had their bone mineral density (BMD) values obtained for the lumbar spine (L(1)-L(4)) and femoral neck according to detailed inclusion criteria. In all women, values of biochemical BTMs, decreased with increasing age up to the age of 45 years, increased steeply among women in their 50s and remained increased in post-menopausal women. Significant increases were evident in all biochemical BTMs in post-menopausal women with >5 years since menopause with the exception of s-OC, u-DPD, and u-PYD. Using stepwise multiple linear regression analysis, several variables were identified (depending on the BTM) as determinants of BTMs including age, BMI, parity, FSH, LH, PTH, s-Ca, s-Mg, s-PO(4) and 25(OH)D. In the reference intervals group, there are no significant correlations between any of the biochemical BTMs and age of menarche, day of menstrual cycle, physical activity, total daily dietary calcium and caffeine intakes and parity. It is recommended that the age range 35-45 years should be used when establishing biochemical BTMs reference intervals in Saudi Arabian pre-menopausal women.

Correlation of bone mineral density with biochemical markers in post menopausal women

To evaluate the magnitude of bone loss in postmenopausal women and to study the effect of a selective estrogen Receptor Modulator, raloxifene, on bone loss by quantitative ultrasound of calcaneus and serum bone specific alkaline phosphatase (BAP). Postmenopausal women with ostesopenia/osteoporosis were assigned randomly to receive placebo (n=30) or raloxifene (60mg/d, n=30) with calcium (500mg/day) and vitamin D (250 IU/day). The bone mineral density (BMD) and BAP levels were measured at the beginning of therapy and six months later. They were subjected to statistical analysis (t test, p value) using SPSS statistical package. 70% of postmenopausal women suffered from osteopenia/osteoporosis. After raloxifene therapy, there was improvement in the BMD but this was not statistically significant (p>0.05). There was a fall in the value of serum BAP by 26.6% (p<0.05). Raloxifene has a favourable effect on bone turnover as evident from changes in BMD and a significant fall in serum BAP.

Prediction of changes in bone mineral density in postmenopausal women treated with once-weekly bisphosphonates

BACKGROUND

In clinical practice, bone mineral density (BMD) determined by dual-energy x-ray absorptiometry is used to monitor response to osteoporosis therapy. However, 1 to 2 yr are usually required to assess patients' BMD responses. The possibility of earlier indicators of a response or nonresponse to treatment, such as changes in bone turnover markers (BTMs), is of interest to physicians and patients.

METHODS

In this post hoc analysis of women treated with once-weekly bisphosphonates, we examined the association of tertile percentage change from baseline in BTMs at 3 or 6 months and association of several baseline clinical characteristics with 24-month percentage change from baseline in BMD and with percentage of patients showing BMD nonresponse (defined as BMD loss at two or more of four sites) at 24 months. Multivariable analysis was performed to determine which factors were independently associated with BMD nonresponse.

RESULTS

Patients in the tertile with the greatest decrease in each of the BTMs had the greatest mean increase in BMD and the lowest percentage of BMD nonresponders at 24 months. Several characteristics were independently associated with BMD nonresponse, including smaller 3-month reductions from baseline in serum C-terminal telopeptide of type 1 collagen, bone-specific alkaline phosphatase, and N-terminal propeptide of type 1 procollagen; younger age of menopause; a family history of osteoporosis; and higher baseline trochanteric BMD. Baseline BTMs were not predictive of 24-month BMD response to therapy. The strongest associations were for changes in BTMs with treatment.

CONCLUSION

In groups of patients, short-term changes in markers of bone turnover appear to be predictors of longer term BMD response and nonresponse to bisphosphonate therapy.

Management of atrophic maxilla in severe osteoporosis treated with bisphosphonates: a case report

Studies investigating whether osteoporosis is a risk factor for using implants have revealed no correlation between possible implant failure and the severity of osteoporosis. However, osteoporotic patients frequently require bone regeneration techniques, because they do not fulfil optimum conditions for implant placement owing to the diminished bone structure and rapid resorption of the alveolar bone. We present a successful case of advanced implant therapy using platelet-rich plasma in a patient with severe osteoporosis who had been previously treated with bisphosphonates. We are not aware that this technique has been previously described in literature.

The amino- and carboxyterminal cross-linked telopeptides of collagen type I, NTX-I and CTX-I: a comparative review

Bone diseases such as osteoporosis or bone metastases are a continuously growing problem in the ageing populations across the world. In recent years, great efforts have been made to develop specific and sensitive biochemical markers of bone turnover that could help in the assessment and monitoring of bone turnover. The amino- and carboxyterminal cross-linked telopeptides of type I collagen (NTX-I and CTX-I, respectively) are two widely used bone resorption markers that attracted great attention due to their relatively high sensitivity and specificity for the degradation of type I collagen, and their rapid adaptation to automated analyzers. However, the clinical performance of both markers differs significantly depending on the clinical situation. These differences have caused considerable confusion and uncertainty. If used correctly, both markers have great potential to improve the management of many bone diseases. We here review the biochemistry, analytical background and clinical performance of NTX-I and CTX-I, as documented in the accessible literature until March 2008.

Increases in BMD correlate with improvements in bone microarchitecture with teriparatide treatment in postmenopausal women with osteoporosis

Increases in BMD are correlated with improvements in 2D and 3D trabecular microarchitecture indices with teriparatide treatment. Therefore, improvements in trabecular bone microarchitecture may be one of the mechanisms to explain how BMD increases improve bone strength during teriparatide treatment.

INTRODUCTION

Bone strength is determined by BMD and other elements of bone quality, including bone microarchitecture. Teriparatide treatment increases BMD and improves both cortical and trabecular bone microarchitecture. Increases in lumbar spine (LS) BMD account for approximately 30-41% of the vertebral fracture risk reduction with teriparatide treatment. The relationship between increases in BMD and improvements in cortical and trabecular microarchitecture has not yet been studied.

MATERIALS AND METHODS

The relationship between increases in BMD and improvements in cortical and trabecular microarchitecture after teriparatide treatment was assessed using data from a subset of patients who had areal BMD measurements and structural parameters from transiliac bone biopsies in the Fracture Prevention Trial. 2D histomorphometric and 3D microCT parameters were measured at baseline and 12 (n = 21) or 22 (n = 36) mo. LS BMD was assessed at baseline and 12 and 18 mo, and femoral neck (FN) BMD was measured at baseline and 12 mo. Pearson correlation was performed to assess the relationship between actual changes in BMD and actual changes in microarchitectural parameters.

RESULTS

Changes in LS BMD at 12 mo were significantly correlated with improvements in trabecular bone structure at 22 mo: 2D bone volume (r = 0.45, p = 0.02), 2D mean wall thickness (r = 0.41, p = 0.03), 3D bone volume (r = 0.48, p = 0.006), 3D trabecular thickness (r = 0.44, p = 0.01), 3D trabecular separation (r = -0.37, p = 0.04), 3D structural model index (r = -0.54, p = 0.001), and 3D connectivity density (r = 0.41, p = 0.02). Changes in LS BMD at 18 mo had similar correlations with improvements in bone structure at 22 mo. Changes in FN BMD at 12 mo were significantly correlated with changes in 2D mean wall thickness (r = 0.56, p = 0.002), 3D bone volume (r = 0.51, p = 0.004), 3D trabecular thickness (r = 0.44, p = 0.01), 3D trabecular separation (r = -0.46, p = 0.01), and 3D structural model index (r = -0.55, p = 0.001).

CONCLUSIONS

Increases in BMD are correlated with improvements in trabecular microarchitecture in iliac crest of patients with teriparatide treatment. Therefore, improvements in trabecular bone microarchitecture may be one of the mechanisms to explain how BMD increases improve bone strength during teriparatide treatment.

Interrelationships between bone microarchitecture and strength in ovariectomized monkeys treated with teriparatide

Bone microarchitecture measured at the iliac crest at 6 mo was confirmed to be a reasonable surrogate for, and a predictor of, architecture and strength of the femoral neck and lumbar vertebra after 18 mo of teriparatide treatment. However, the data taken together showed the importance of cortical bone volume for vertebra to assess pharmacological effects on bone quality.

INTRODUCTION

Improvements in bone architecture with teriparatide treatment are suggested to contribute to fracture risk reduction in osteoporotic patients. Teriparatide significantly improves microarchitecture in the iliac crest of humans by stimulating bone modeling and remodeling processes that differ dramatically from those induced by antiresorptives. The relationship between improvements of bone microarchitecture and improvements of bone strength with teriparatide treatment has not yet been fully studied.

MATERIALS AND METHODS

Ovariectomized monkeys were administered vehicle (n = 20); teriparatide 1.0 microg/kg/d (n = 19); or teriparatide 5.0 microg/kg/d (n = 21) for 18 mo. Iliac crest biopsies were obtained at 6 and 15 mo after initiation of treatment. Animals were killed after 18 mo of treatment, and adjacent vertebrae or contralateral proximal femora were processed for biomechanical or histomorphometric analyses. Pearson correlation analyses were performed to assess the relationship between biomechanical and static histomorphometric parameters of lumbar vertebra, femoral neck, and iliac crest biopsies.

RESULTS

Static histomorphometric parameters of the 6- and 15-mo biopsies were significantly correlated with the vertebral and femoral neck parameters obtained at 18 mo of teriparatide treatment. Iliac crest biopsy parameters at 6 and 15 mo also correlated with vertebral and femoral neck strength at 18 mo. Static histomorphometry of the lumbar vertebra and femoral neck at 18 mo also significantly correlated with strength at these sites. However, cortical bone volume of the lumbar vertebrae had the strongest correlation with vertebral and femoral neck strength (r = 0.74 and 0.71, respectively).

CONCLUSIONS

Teriparatide dose dependently improved cortical and trabecular microarchitecture of vertebra and femoral neck, as well as trabecular microarchitecture of the iliac crest. Bone microarchitecture at all sites was significantly correlated with lumbar vertebra and femoral neck strength. Cortical bone volume of vertebra had the strongest correlation with vertebral and femoral neck strength. Therefore, structural improvement seemed to be part of the mechanism for improved strength observed with teriparatide treatment. Trabecular bone architecture of the iliac crest at 6 mo also correlated with vertebral and femoral neck strength, as did femoral neck (cortical and trabecular) histomorphometry and trabecular histomorphometry of vertebra after 18 mo of treatment. Because clinical assessment of cortical bone volume is not readily possible for vertebra noninvasively, these findings confirm the importance of iliac crest biopsies to monitor skeletal health and show that biopsies are a reasonable surrogate to assess spine and femoral neck structure and function.

Fracture risk reduction during treatment with teriparatide is independent of pretreatment bone turnover

INTRODUCTION

Teriparatide is a bone formation agent that increases bone turnover and mass, resulting in an increase in bone strength and a decrease in fracture risk.

METHODS

The primary purpose of this analysis was to evaluate the association between pretreatment bone turnover marker (BTM) concentrations and the absolute and relative fracture risks after adjusting for baseline femoral neck BMD, number of prevalent vertebral fractures, and age. Because femoral neck BMD is commonly attained in the assessment of patients at risk for osteoporosis, we examined the ability of a multivariate assessment including pretreatment BTM concentration and femoral neck BMD to predict future fracture risk after adjusting for the number of prevalent vertebral fractures. We examined data from the Fracture Prevention Trial, a study designed to determine the effect of teriparatide 20 mcg/day and teriparatide 40 mcg/day on vertebral and nonvertebral fracture risk in postmenopausal women with osteoporosis. BTM were analyzed in two subsets of women within the Fracture Prevention Trial, and included serum bone-specific alkaline phosphatase (BSAP), serum carboxy-terminal extension peptide of procollagen type I (PICP), serum amino-terminal extension peptide of procollagen type I (PINP), urinary free deoxypyridinoline (DPD), and urinary N-terminal telopeptide (NTX).

RESULTS

Teriparatide significantly reduced the risk of fracture [four BTM subset (n = 520), placebo = 14.3%, teriparatide = 5.8%, P < 0.05; PINP subset (n = 771), placebo = 17.7%, teriparatide = 5.5%, P < 0.05]. Subjects with the highest pretreatment BTM concentrations had the greatest fracture risk. Teriparatide-mediated absolute risk reduction was greatest for women with high pretreatment bone turnover; however, the relative fracture risk reduction was independent of pretreatment bone turnover. After adjusting for pretreatment BTM and number of prevalent vertebral fractures, baseline femoral neck BMD was not a significant predictor of fracture risk.

CONCLUSION

Teriparatide-mediated relative fracture risk reduction was independent of pretreatment bone turnover, demonstrating that this therapy offers clinical benefit to patients across a range of disease severity.

Effect of soy protein/animal protein ratio on calcium metabolism of the rat

OBJECTIVE

This study examined the effects of a ratio of soy protein to animal protein on bone metabolism of rats.

METHODS

Experimental groups were a high soy protein group (200 g of soy protein and 0 g of casein per kilogram of diet; HSoy), a middle soy protein group (100 g of soy protein and 100 g of casein per kilogram of diet; MSoy), a low soy protein group (50 g of soy protein and 150 g of casein per kilogram of diet; LSoy), and a no soy protein group (0 g of soy protein and 200 g of casein per kilogram of diet; NSoy). Calcium excretion and retention, biochemical parametrically related calcium metabolism, and bone mineral density were measured. Statistical analysis was performed with SAS software.

RESULTS

Urinary excretion of calcium was significantly high in the LSoy and NSoy groups, and there was no difference in absorption of calcium across experimental groups. Calcium retention was significantly higher in the HSoy and MSoy groups than in the LSoy and NSoy groups. Experimental groups showed no differences in the activity of alkaline phosphatase. The casein group (NSoy) showed a remarkably lower degree of serum osteocalcin concentration. The concentration of deoxypyridinoline in urine showed an increasing tendency, i.e., HSoy and MSoy < LSoy < NSoy, indicating that at a higher degree of animal protein/soy proteins, its concentration increases. Wet weight of the femur appeared to be significantly greater in the MSoy and LSoy groups than in the NSoy group. Ash content of the femur and bone density were highest in the MSoy group, with the ratio of 1:1 between soy protein and animal protein.

CONCLUSIONS

This study indicated that deoxypyridinoline concentration was lower and the density of osteocalcin was higher in the MSoy group than in the NSoy group, and that calcium retention was high and bone mineral density was the highest in the MSoy group. The ratio of soy to animal protein that seemed to have the most positively significant effect on calcium metabolism was 1:1.

Comparing raloxifene with continuous combined estrogen-progestin therapy in postmenopausal women: Review of Euralox 1

OBJECTIVES

To review the main findings of the Euralox 1 study - a multicentre, randomised, double-blind study conducted in 1008 healthy postmenopausal women allocated to raloxifene (n = 495) or continuous combined estrogen-progestin therapy (ccEPT; n = 513) for 6 months -- and provide an overview of the risks and benefits of raloxifene and ccEPT.

METHODS

A review is provided of previously published findings on uterine safety (bleeding rates and changes in endometrial thickness and uterine volume), gynaecological adjudication, cardiovascular risk (lipids, fibrinogen), adverse events, compliance, treatment satisfaction and quality of life. New data on biochemical markers of bone turnover (serum N-telopeptides and C-terminal telopeptides of type I collagen; NTX and CTX) assessed before and after 6 months' treatment are presented.

RESULTS

Raloxifene caused less uterine bleeding than ccEPT and, unlike ccEPT, did not alter endometrial thickness or uterine volume. Serum CTX and NTX levels were reduced in both treatment groups, but the reduction was significantly greater with ccEPT. The two treatments had differential effects on lipids and fibrinogen levels; raloxifene had more favourable effects on serum HDL, the LDL/HDL ratio, and plasma fibrinogen. Raloxifene was associated with fewer adverse events or discontinuations, and this was associated with higher treatment satisfaction and better self-reported compliance.

CONCLUSIONS

The clinical risk-benefit profile of raloxifene derived from the intermediate endpoints of this study suggests that it may be a better alternative to ccEPT for preventing long-term postmenopausal health risks in healthy postmenopausal women who are not suffering from vasomotor symptoms.

Biochemical Markers of Bone Turnover in the Clinical Development of Drugs for Osteoporosis and Metastatic Bone Disease

Biochemical markers of bone turnover are used increasingly during the clinical development of drugs for the treatment of metabolic bone diseases such as Paget's disease, osteoporosis and cancer that has metastasised to the bone. However, assessing the optimal value of these markers is often complicated, and such an assessment is an obvious prerequisite for rational use of the markers and, consequently, potential improvement of clinical drug development. Biochemical markers of bone turnover are substances in the blood or urine that are produced or released during bone remodelling. They provide semiquantitative information on bone remodelling, and are often the most adequate tool to describe the pharmacodynamics of the drug. Their use has increased considerably because of dose-effect relationships that have been seen with certain drugs, but also because they have proven relationships with clinical outcomes in several metabolic bone diseases. However, there is a lack of information on the kinetics of these markers, and the immunoassays that are frequently used in their monitoring often measure a mixture of fragments rather than a single molecular entity. For drug development it should also be realised that different markers, but also different assays for the same marker, may provide different results, considerably limiting the ability to compare results. In postmenopausal osteoporosis, relationships have been shown between several biochemical markers of bone turnover, and either fracture risk and/or the antifracture efficacy of drugs. Such relationships can be used for the development of drugs with similar mechanisms of action, but also for the development of these drugs for closely related indications, such as corticosteroid-induced osteoporosis. In both of these instances, data on effects on biochemical markers of bone turnover are usually employed in combination with information about effects on bone mineral density. However, the relationships of these parameters with clinical outcomes may be remarkably different for drugs with alternative mechanisms of action, challenging the use of the markers for the development of new drugs for the treatment of patients with osteoporosis. At present, the pharmacological treatment of cancer that has metastasised to the bone is limited to several bisphosphonates. Recent studies have shown relationships between the normalisation of levels of biochemical markers of bone turnover and clinical outcomes, and prospective studies investigating the application of such relationships are ongoing. The markers may play an important role in the optimisation of registered bisphosphonate treatments. However, their role in the development of new drugs is still limited to dose selection, and potential relationships with clinical outcomes remain to be investigated in instances of new mechanisms of action. Biochemical markers of bone turnover are a valuable asset for drug development, but their rational use is determined by a number of variables. Correctly manipulating these may improve clinical development of drugs for the treatment of patients with metabolic bone diseases such as osteoporosis and cancer metastatic to the bone.

Hyperbilirubinemia is not a major contributing factor to altered bone mineral density in patients with chronic liver disease

Reduced bone density is commonly encountered in patients with chronic liver disease. Prior studies have shown that unconjugated bilirubin inhibits osteoblast activity and function in vitro and in animal models of bone mineralization. To determine whether hyperbilirubinemia promotes the development of hepatic osteodystrophy, bone mineral density (BMD) was measured by dual energy X-ray absorptiometry in a cohort of 86 consecutive patients with chronic liver disease referred for liver transplant evaluation. The mean age of the study population was 52 years (range, 22-73), in which 52% were female and 90% were white. Average bone density values were significantly lower than expected for age, race, and sex, with Z-scores for the femoral neck and spine of -0.50 (95% confidence interval [CI] -0.63 to -0.37; p=0.0003) and -0.69 (95% CI -0.85 to -0.52; p=0.0001), respectively. Sixty-one subjects (71%) exhibited reduced BMD (T-score of femoral neck or spine<or=-1 standard deviation [SD] below the young-adult mean), and 18 subjects (21%) met criteria for osteoporosis (T-score<-2.5 SD). Stepwise logistic regression analyses identified significant associations between BMD and serum creatinine, alkaline phosphatase, age, and gender. On the other hand, neither unconjugated, nor conjugated, nor total serum bilirubin levels were found to predict diminished BMD. The lack of association between serum unconjugated bilirubin levels and bone mineralization was validated in hyperbilirubinemic Gunn rats, in which BMD and serum osteocalcin levels were no different than in wild-type rodents. In conclusion, the finding that serum bilirubin levels do not correlate with reduced BMD in patients with end-stage liver disease, and that chronic unconjugated hyperbilirubinemia does not lead to alterations in bone mineralization in Gunn rats, suggests that bilirubin is not a major contributing factor to hepatic osteodystrophy.

The effect of calcitonin on biochemical markers and zinc excretion in postmenopausal osteoporosis

OBJECTIVES

A double-blind, randomized, placebo-controlled trial was conducted in women with postmenopausal osteoporosis to evaluate effects on biochemical markers and urinary excretion of zinc (Zn) of calcitonin therapy.

METHODS

Patients were required to have a bone mineral density (BMD) of 2.5 S.D. or more below the young adult mean either at the postero-anterior lumbar spine or at the femoral neck. Subjects were eligible for our study if they were 50 years or older, with at least 5 years of menopause, and in good general health as determined by medical history and a routine clinical blood analysis. The patients were randomly assigned to receive intranasal salmon calcitonin (200 IU/day; 50 patients) or placebo (50 patients). All patients received supplemental calcium (1000 mg/day). Additionally, 40 age-matched, demographically similar, healthy postmenopausal women were also selected as controls. Measurements of cross-linked N-telopeptides of type I collagen (uNTx), osteocalcin (sOC), and urinary zinc concentration were done. All parameters were measured before therapy and again after 1, 3 and 6 months.

RESULTS

After 3 and 6 months of treatment, a higher decrease of most indices was observed in the calcitonin group. A statistically significant decrease occurred in the levels of sOC, uNTx and uZn after 3 and 6 months in patients receiving calcitonin therapy (P<0.05). Levels of sOC and uNTx in calcitonin group were significantly different after 3 and 6 months from both placebo and baseline values of calcitonin group (P<0.05). Levels of sOC, uNTx and uZn decreased about 40, 46 and 37%, respectively, in calcitonin group at 6 months after the start of treatment.

CONCLUSIONS

Our study suggests that values of uNTx, uZn and sOC were significantly lower in the patient group than those in control group and in postmenopausal women with osteopororsis, calcitonin reduces the concentrations of uNTx, uZn and sOC.

Early changes in biochemical markers of bone formation predict BMD response to teriparatide in postmenopausal women with osteoporosis

The relationship between early changes in biochemical markers of bone turnover and the subsequent BMD response to daily teriparatide therapy in women with postmenopausal osteoporosis was studied. Changes in five biochemical markers, obtained from a subset of women enrolled in the Fracture Prevention Trial, were examined. Early increases in the PICP and the PINP were the best predictors of BMD response to teriparatide in this analysis.

INTRODUCTION

Early reductions in biochemical markers of bone turnover with antiresorptive therapy negatively correlate with subsequent increases in BMD. We undertook this analysis to determine if early changes in biochemical markers with teriparatide therapy predict subsequent increases in BMD.

MATERIALS AND METHODS

In the Fracture Prevention Trial, 1637 postmenopausal women with osteoporosis were randomized to receive daily, self-administered, subcutaneous injections of placebo, teriparatide 20 microg/day, or teriparatide 40 microg/day. Serum concentrations of two bone formation markers (bone-specific alkaline phosphatase [bone ALP] and the carboxy-terminal extension peptide of procollagen type 1 [PICP]) and urinary concentrations of two bone resorption markers (free deoxypyridinoline [DPD] and N-terminal telopeptide [NTX]) were assessed in a trial population subset (n = 520) at baseline and at 1, 3, 6, and 12 months. We also assessed serum concentrations of another bone formation marker, the amino-terminal extension peptide of procollagen type 1 (PINP), in a subset of 771 women at baseline and 3 months. Lumbar spine (LS) BMD was measured by DXA at baseline and 18 months. Femoral neck BMD was measured at baseline and 12 months.

RESULTS AND CONCLUSION

Baseline bone turnover status correlated positively and significantly with BMD response. The highest correlations occurred for the LS BMD response to teriparatide 20 microg/day. Among all studied biochemical markers, increases in PICP at 1 month and PINP at 3 months correlated best with increases in LS BMD at 18 months (0.65 and 0.61, respectively; p < 0.05). The relationships between these two biochemical markers and the LS BMD response were stronger than the corresponding relationships for the femoral neck BMD response. Using receiver operator curve analysis, we determined that the increases in PICP at 1 month and PINP at 3 months were the most sensitive and accurate predictors of the LS BMD response.

Bone response to treatment with lower doses of conjugated estrogens with and without medroxyprogesterone acetate in early postmenopausal women

Lower doses of conjugated estrogens (CE) alone or combined with lower doses of medroxyprogesterone acetate (MPA) increase mean bone mineral density (BMD) from baseline at the spine and hip in early postmenopausal women. However, not all women on therapy gain BMD. The incidence of continued bone loss (defined as a loss of BMD of > 2% from baseline) among women using lower doses of CE and CE/MPA is unknown. This randomized, double-blind, placebo-controlled, multicenter substudy of the Women's Health, Osteoporosis, Progestin, Estrogen (Women's HOPE) trial investigated the incidence of continued bone loss with lower-dose CE and CE/MPA. Eight hundred twenty-two healthy postmenopausal women with intact uteri received CE 0.625, CE 0.625/MPA 2.5, CE 0.45, CE 0.45/MPA 2.5, CE 0.45/MPA 1.5, CE 0.3, CE 0.3/MPA 1.5 (all doses in mg/day), or placebo for 2 years along with 600 mg/day of calcium. Changes from baseline in spine and total hip BMD were compared among treatment groups in an intent-to-treat analysis. At 12 months, < 10% of women on active treatment lost > 2% of spinal BMD (except CE 0.3/MPA 1.5 [15.6%]), compared with 41.2% of women on placebo. At 24 months, the percentages of women on active treatment who lost > 2% of spine BMD ranged from 4.5% with CE 0.45/MPA 1.5-15.6% with CE 0.3/MPA 1.5, compared with 55.2% of women taking placebo. More than 85% of women on active treatment did not experience continued BMD loss at the hip at 12 months and 24 months, in contrast to 30.6% of women on placebo at 12 months and 36.5% at 24 months. Women receiving active treatment who lost > 2% of spine or hip BMD also had a lesser reduction in biochemical markers of bone turnover. In summary, continued bone loss among early postmenopausal women treated with lower doses of CE or CE/MPA is uncommon.

Drugs used to treat osteoporosis: the critical need for a uniform nomenclature based on their action on bone remodeling

There continues to be uncertainty about the classification of available drugs for treating osteoporosis. We find that grouping them into anti-catabolic and anabolic classes based on the mechanisms of their action on bone remodeling and fracture reduction removes ambiguities and provides a relatively straightforward classification. The recent introduction of teriparatide into clinical practice initiated the era of anabolic therapy for osteoporosis, but it is still unclear how to define an anabolic drug. All drugs that increase bone mass do so by affecting bone remodeling. When their mechanisms of action on bone remodeling and on fracture reduction are considered, we find that anti-osteoporotic drugs fall naturally into either anti-catabolic or anabolic classes. Anti-catabolic drugs increase bone strength and reduce fractures mainly by decreasing the number of bone multicellular units (BMUs). This reduces perforative resorption and preserves skeletal microarchitecture (by preventing further structural damage to trabecular bone and increased porosity in cortical bone induced by high bone remodeling). Reduction in bone remodeling by anti-catabolic drugs may increase bone mass moderately during the interval in which previously initiated BMUs are completing mineralization. Some anti-catabolic drugs may also enhance the formation phase of the remodeling cycle, but their major action is to reduce overall bone turnover (i.e., the number of BMUs in bone). In contrast, anabolic drugs increase bone strength and reduce fractures by substantially increasing bone mass as a result of an overall increase in the number of BMUs combined with a positive BMU balance (the magnitude of the formation phase is greater than that of the resorption phase). Some anabolic drugs also induce renewed modeling, increase periosteal apposition and repair of trabecular microstructure. We hope that this classification will serve as a starting point for continued discussion on the important issue of nomenclature.

Marcadores bioquímicos de remodelado en el estudio de la masa ósea en la mujer con menopausia reciente sin osteoporosis

BACKGROUND AND OBJECTIVE

To date, there have not been performed enough studies in Spain to analyze the usefulness of biochemical bone markers in postmenopausal and non-osteoporotic women.

POPULATION AND METHOD

We studied several groups of women, ages between 17 and 30 years, 30-45 years, premenopausal and recently postmenopausal in order to know the reference values of some biochemical bone markers along 2 years in premenopausal and postmenopausal women (postmenopausal divided in 2 groups: those under treatment with ordinary hormonal replacement therapy [HRT], and those without it).

RESULTS

Values of biochemical bone markers were higher in postmenopausal and in 17-30 years group than in premenopausal and 30-45 years group (p < 0.05). Absolute values and the change in bone markers (%) were higher in postmenopausal and non-osteoporotic women under HRT than in those without HRT (% change: OC, 35,72 vs 4.45 [p < 0.01]; ALPo, 13,13 vs 27.06 [p < 0.01]; NTx, 42.74 vs 10.93 [p < 0.01]; fDPD, 21.07 vs 28.49 [p < 0.05]; betaCrossLaps, 50,17 vs 23.04 [p < 0.01]).

CONCLUSIONS

We have defined reference values in our region and have proved that biochemical bone markers (absolute values and their change from the basal value) represent a useful tool in monitoring hormonal replacement therapy in recently postmenopausal and non-osteoporotic women.

Requirements for improving quality in the measurement of bone markers

BACKGROUND

A number of biochemical assays readily detect molecules released from the bone matrix and collagen degradation in both serum and urine specimens. The variability of bone biochemical markers is still an issue of practical concern limiting their wider clinical use, and compromising the management of the individual patient. The aim of the present study was to define quality specifications of bone markers measurement in the total testing process.

METHODS

The different sources of biological variability of biochemical bone marker were assessed according to the current knowledge and categorized as pre-analytical, intra-analytical and post-analytical.

RESULTS

The identification of factors influencing bone marker measurements allowed recommendations to be made for decreasing pre- and intra-analytical variation in order to improve laboratory performance. The assessment of post-analytical sources of variation, moreover, involves the practical use of bone markers in identifying individual women at risk of fractures and the identification of non-responders, providing adequate limit value, least significant change value or optimal threshold of bone marker change.

CONCLUSIONS

Laboratory services may improve the potential clinical applications of biochemical markers of bone remodeling by improving method standardization, defining and reducing pre-analytical and analytical variables and providing reports that specify analytical and biological variation or cut-off values, thus facilitating data interpretation or reports.

Reference database of biochemical markers of bone turnover for the Japanese female population. Japanese Population-based Osteoporosis (JPOS) Study

The present study was conducted as a part of the Japanese Population-based Osteoporosis (JPOS) Study to establish reference values on the biochemical markers of bone turnover in the general Japanese female population over an applicable age range. The study recruited 3250 women aged 15-79 years, randomly selected from five municipalities throughout Japan, and obtained measurements of serum osteocalcin (OC) and bone-specific alkaline phosphatase (BAP); free and total forms of immunoreactive deoxypyridinoline, free pyridinolines and type I collagen cross-linked C-terminal telopeptide (CTx) in urine; serum intact parathyroid hormone (PTH) and 1,25 dihydroxy vitamin D (1,25 (OH)2D); and bone density at the spine, hip and distal forearm. After excluding subjects with apparent or suggested abnormalities affecting bone mass, 2535 (78%) subjects were further analyzed. The authors presented 5-year age-specific mean values of the markers and mean marker levels derived from women aged 30-44 years with normal bone density as a healthy young adult reference. Values of the markers decreased with increasing age before the age of 40, increased steeply among subjects in their 50s, and remained elevated in the elderly. Serum calcium, phosphorus, PTH and 1,25 (OH)2D levels were higher in postmenopausal women than in premenopausal women. However, 1,25 (OH)2D was lower among early postmenopausal subjects. The levels of OC, BAP, CTx, PTH and 1,25(OH)2D were significantly greater for women with osteoporosis than for those without. The diagnostic value of the markers was limited as the sensitivity and specificity ranged from 55% to 60%. These findings will aid health professionals in the correct assessment of bone turnover status in Japanese women over a wide range of age.

Hormone replacement therapy: controversies, pros and cons

Hormone replacement therapy (HRT) is a complicated clinical issue that requires an in-depth risk/benefit assessment. The term HRT includes both oestrogen plus progestin therapy (OPT) and oestrogen-only therapy (OT). Much research has been done with the former, but additional research is still needed for the latter. This chapter aims to provide a comprehensive overview of the key risks and benefits in order to assist clinicians and patients confronting this issue. In approaching the vast amount of data on HRT a caveat is in order: many of the issues involved are not black and white. The clinical data are often conflicting and careful analysis is required. Despite the discrepancies between the various HRT studies, there is much to be gleaned from a close examination of the data. The primary risks associated with HRT use are related to breast cancer and cardiovascular health. Recent clinical trial data have pointed to a slight increase in the number of breast cancers among women using HRT compared to placebo. With regard to cardiovascular health, the data have shown an increase in stroke and (VTE) but there is also evidence of a possible cardioprotective effect. The major benefits include relief of menopausal symptoms (including vasomotor instability, sexual dysfunction, mood, fatigue and skin issues) and a decrease in fracture risk.

What information on quality specifications should be communicated to clinicians, and how?

BACKGROUND

Quality specifications, the level of performance required to facilitate clinical decision-making, not only have a central role in quality management in the laboratory but are also essential for assuring the interpretation and utilization of laboratory data by physicians. Consensus has been reached on the hierarchy of criteria for quality specifications. However, the information on quality specifications that should be communicated to clinicians, and the way in which this information should be given, is still widely debated.

METHODS

Laboratory tests have been grouped into four categories including uni-modal, and bi-modal distributions, tests used in patients monitoring and in evaluating the response to therapy (serial measurements), and, finally, tests that require interpretive comments. The most suitable and informative ways to communicate quality specifications to clinicians have been proposed for each category.

RESULTS

For tests with a uni-modal distribution, the decision limits should replace traditional reference values in the report. For tests with a bi-modal distribution, in addition to traditional reference values, some flags based on the uncertainty (i.e., analytical and biological variability) of laboratory data, can be included to help clinicians interpret laboratory data. For tests used in monitoring patients and in evaluating the response to therapy (serial measurements), the reference change value or the most effective threshold of the difference between two consecutive results should be indicated. For tests/test batteries that require interpretive comments, these should be added to the report and discussed in multidisciplinary meetings and interpretive rounds to promote knowledge of a more objective evaluation of laboratory data.

CONCLUSIONS

A proposal has been made to improve the way laboratory results are communicated to clinicians, with practical information derived from quality specifications. By providing clinicians with information on quality characteristics and the degree of uncertainty, a more objective interpretation of laboratory data may be possible, and data may be more appropriately utilized for diagnosis and monitoring.

A comparative review of the risks and benefits of hormone replacement therapy regimens

The Women's Health Initiative (a large, randomized, placebo-controlled trial) investigated the effect of conjugated equine estrogens combined with medroxyprogesterone acetate on specific potential long-term benefits and risks. A review of the clinical studies that have investigated different types and regimens of estrogens combined with progestins was conducted to assess how applicable the results of the Women's Health Initiative are to hormone replacement therapy regimens in general. The studies that were reviewed were limited to randomized clinical trials and observational studies that have been published over the last 15 years (1987-2002) and to meta-analyses and reviews that may have included the literature before 1987. The increased risks for venous thromboembolism, stroke, coronary heart disease, and breast cancer that were identified in the Women's Health Initiative trial have also been reported with postmenopausal hormone therapies that contain a variety of estrogen and progestin products. The beneficial effects that were noted in the Women's Health Initiative, with respect to reductions in fractures and colorectal cancer, have not been evaluated in large, randomized controlled trials that use different estrogen/progestin combinations; however, observational trials that used a variety of estrogen or hormone replacement therapy products and randomized clinical studies that evaluated bone mineral density (an excellent predictor of fracture risk) with different estrogen/hormone replacement therapy regimens would suggest that results would be similar to those found in the Women's Health Initiative. Although the relief of menopausal symptoms, the primary reason women seek treatment, was not included in the overall benefit/risk analysis of the Women's Health Initiative, numerous trials suggest that all therapies are effective. Overall, these data indicate that the benefit/risk analysis that was reported in the Women's Health Initiative can be generalized to all postmenopausal hormone replacement therapy products.

Relationship between changes in biochemical markers of bone turnover and BMD to predict vertebral fracture risk

The change in BMD is a poor predictor of vertebral fracture risk after raloxifene treatment. One-year percent change in bone turnover and BMD was used to predict vertebral fracture risk. The percent change in osteocalcin was determined to be a better predictor of vertebral fracture risk than BMD.

INTRODUCTION

The association between baseline BMD and fracture risk is well understood. However, the relationship between changes in BMD and fracture risk is not well defined. It has previously been demonstrated that BMD change was a poor predictor of vertebral fracture risk in raloxifene-treated women, whereas bone turnover markers were significantly associated with fracture risk. In the current analysis, we explore the prediction of vertebral fracture risk using changes in both BMD and bone turnover.

MATERIALS AND METHODS

The Multiple Outcomes of Raloxifene Evaluation (MORE) trial was a randomized, placebo-controlled trial of 7705 women with osteoporosis treated with raloxifene 60 or 120 mg/day for 3 years. Markers of bone turnover were measured in one-third of the study population (n = 2503), and the present analyses include these women. Logistic regression models were constructed using one-year percent changes in BMD and bone turnover and relevant baseline demographics to predict the risk of vertebral fracture with pooled raloxifene therapy at 3 years. All covariates were standardized before modeling to facilitate direct comparisons between changes in BMD and bone turnover.

RESULTS AND CONCLUSION

Prevalent vertebral fracture status (p < 0.0001), baseline lumbar spine BMD (p < 0.0001), and number of years postmenopausal (p = 0.0005) were independent predictors of fracture risk in raloxifene-treated patients. Therapy-by-change in femoral neck BMD (p = 0.02) and therapy-by-change in osteocalcin (OC; p = 0.01) were also significant for all treatment groups, indicating that changes in BMD and OC have different effects on fracture risk for the placebo and pooled raloxifene groups. The final model included significant baseline variables and change in OC (p = 0.01), whereas change in femoral neck BMD was not significant. After adjustment of each significant baseline variable, the percent change in OC was better able to predict the reduction in vertebral fracture risk than the percent change in femoral neck BMD in patients treated with raloxifene.

Pulsed estrogen therapy in prevention of postmenopausal osteoporosis. A 2-year randomized, double blind, placebo-controlled study

The aim of this study was to evaluate the efficacy of pulsed estrogen therapy (intranasal 17beta-estradiol) in the prevention of postmenopausal bone loss. A total of 386 women (40-65 years old), less than 5 years past menopause, were randomized to intranasal placebo, 17beta-estradiol 150 micro g, or 300 micro g daily for 2 years. Women with an intact uterus received micronised progesterone 200 mg per day, 14 days of each 28-day cycle. Women randomised to placebo-treatment received placebo progesterone. The primary endpoints were changes in BMD at the spine (L2-L4) and femoral neck. Secondary endpoints were changes in bone turnover markers: serum osteocalcin (sOC) as a marker of bone formation and urinary C-terminal telopeptides (uCTX) as a marker of bone resorption. BMD increased at all measured sites in women receiving active treatment in a dose-related manner, the difference compared to placebo being 5.2% and 6.7% at the spine, and 3.2% and 4.7 % at the hip, respectively, with 150 microg and 300 microg ( P<0.001). On the other hand, a decrease versus baseline of -3.2% and -3.3% at the spine and hip, respectively, was observed in women receiving placebo ( P<0.001). In the patients with at least one risk factor for osteoporotic fracture, the difference between placebo and 150 microg or 300 micro g was even higher at the spine (5.4% and 7.4%, respectively), and at the femoral neck (4.0% and 5.2%, respectively). Correspondingly, uCTX decreased from baseline by 39% and 46 %, and sOC by 22% and 27%, in the 150 micro g group and 300 micro g group (all P<0.001 versus placebo). A strong correlation was found between variations of bone turnover markers after 1 year and BMD after 2 years, emphasizing that bone markers can predict BMD response during hormonal treatment. Acceptability and general tolerance were good. This study demonstrates that pulsed estrogen therapy at the dose of 150 microg and 300-microg per day prevents bone loss in a dose-dependant manner at each site studied, and normalizes bone turnover markers to premenopausal levels.

[Comparison of changes in biochemical markers of bone turnover after 6 months of hormone replacement therapy with either transdermal 17 beta-estradiol or equine conjugated estrogen plus nomegestrol acetate]

OBJECTIVE

To compare changes in biochemical markers of bone turnover in postmenopausal women who received sequential discontinuous hormone replacement therapy (HRT) with either transdermal 17 beta-estradiol gel (group 1) or oral equine sulfoconjugated estrogen (group 2), plus nomegestrol acetate.

PATIENTS AND METHOD

Prospective, open, randomized, controlled trial, conducted on 3 parallel groups of 106 postmenopausal women. All treated groups received estrogen therapy for 25 consecutive days every month. The estrogen used was either 1.5 mg/day of transdermal 17 beta-estradiol gel (group 1) [N = 42, average age (AA) = 51.6 years, average duration of menopause (ADM = 21.5 months)], or 0.625 mg/day of oral equine sulfoconjugated estrogen (group 2) [N = 39, AA = 51.3 years, ADM = 16.8 months]. In all cases nomegestrol acetate 5 mg/day was added for 12 consecutive days every month. The control group comprised 25 patients, [AA = 53.4 years, ADM = 33.7 months]. Two bone resorption markers: urinary cross-linked N-telopeptide and C-telopeptide of type I collagen (U-NTX/Cr, U-CTX/Cr), and a bone formation marker: serum bone specific alkaline phosphatase activity were measured before and 6 months after treatment start.

RESULTS

Significant decreases from baseline values were observed for the 3 biochemical markers in both treated groups compared with control (P < 0.001). There were no significant differences in changes between the 2 treated groups for the 3 biochemical markers. The mean percentage change in the 3 biochemical markers was: from -9.3 to -45.5% in group 1, from -20.5 to -39% in group 2, and from -3.3 to 2% in control group. In group 1, the mean percentage decreases in U-CTX reached optimal threshold of bone turnover change (-45%) which is considered by the International Osteoporosis Foundation as clinically relevant because it predicts an increase in BMD greater than 3% when treatment is maintained over a long term.

DISCUSSION AND CONCLUSION

Both treated groups induced a significant comparable decrease of bone turnover markers after 6 months of intervention, compared with control. The group treated with cyclic administration of transdermal 17 beta-estradiol (1.5 mg/day) and nomegestrol acetate (5 mg/day) showed a bone resorption markers decrease corresponding to the threshold of clinical relevance described in the international literature and predictive of positive BMD response in long term.