Measurement Of Bone Alkaline Phosphatase Research Articles

SUN-LB73 Is It Possible to Optimize Resources in Bone-Alkaline Phosphatase Medical Request?

INTRODUCTION: Bone metabolism assessment includes total alkaline phosphatase (ALP) and more specifically the bone-alkaline phosphatase (BAP) as markers of bone formation. Its measurement is important for diagnosis and in bone pathology treatment following-up. In our setting, a ten-fold price for BAP has raised the necesity to review in how many cases its request has been justified. AIM: Establish through an appropiate statistical analysis, cut-off values of ALP that could guarantee to perform BAP measurements. Its analysis would allow us to make a demand adequacy. MATERIALS AND METHODS: A retrospective study was carried out on laboratory analysis orders of 405 adult women. We separate them into the following groups: (G1): 48 premenopausal womens (pre) and 357 post menopausal women (pos): (G2)133 <60 years-old, (G3)135: 60-69 years-old and (G4)89: >70 years-old. All patients had measurements of both analytes; ALP (colorimetric method, Roche Cobas, Reference value (RefV)=40-130 UI/L) and BAP (QLIA, Liaison Diasorin, RefV pre=3-19 ug/mL, pos=6-26 ug/mL). Statistic analysis: ROC-Plot to define cut-off value (we define as true positive BAP values over RefV). Kruskal Wallis, Dunn test to compare all the groups. RESULTS: (median and range): ALP(UI/L) G1: 81(38-265) G2: 88(47-211)*, G3: 85(39-213) y G4: 80(40-138) (*p<0.05 G2vsG4). BAP (ug/L) G1: 13.6(5.1-106), G2: 14.3(3.5-61.5)*, G3: 13.9(2.9-52.5) and G4: 11.6(2.0-29.6), (*p<0.05 G2vsG4). We observe that 73% of G1, 93.5% of G2, 92.6% of G3, 97.7% of G4 has showed normal values. The ROC plot analysis showed the best cut-off for ALP in G1=87 (S=92%,Sp=85%,AUC=0.955). If, using this cut off we had processed 18 BAP which 6 patients would have been normal (33.4%). In G2=127 (S=100%, Sp=97.6%, AUC=0.996) using this cut off we had processed 13 BAP, which 4 patients would have been normal (30.8%). Meanwhile in G3=102(S=100%, Sp=85.6%, AUC=0.97) we had processed 30 BAP and G4=120 (S=100%, Sp=96.5%, AUC=0.966) we had processed only 6 BAP. CONCLUSIONS: Application of the calculated cut-off allowed us to investigate 97% of the pathological BAPs. The measurement of ALP first, would guarantee to process only 17% of the requested BAPs. This suggestion would result in a significant saving of our resources, maintaining the quality of care. It is necessary to apply cut-off according to age to justify the BAP assesment. Physicians must define the appropriate exceptions.

Age- and sex-matched reference curves for serum collagen type I C-telopeptides and bone alkaline phosphatase in children and adolescents: An alternative multivariate statistical analysis approach

IntroductionThe availability of pediatric age- and sex-matched reference curves for bone markers is essential for appropriate assessment of bone turnover and treatment follow-up of bone disorders. The aim of this work was to obtain updated reference equations for collagen type I C-telopeptides (CTX-1) and bone alkaline phosphatase (BAP) by using an alternative statistical approach.The study included 1502 Italian pediatric subjects from 6months to 16years of age (686 females and 816 males) subjected to CTX-1 and BAP measurement during a six-year period. MethodsThe unselected population of patients was used for the calculation of age- and sex-matched reference curves by using a multivariate statistical analysis after an appropriate validation with a selected population of 184 healthy subjects (6months-16years; 88 females and 96 males). The effect of age, sex, puberty based on Tanner stage evaluation and anthropometrics on the variations of the two bone markers was then studied. ResultsPediatric reference curves were obtained for CTX-1 and BAP from 3465 results retrieved by our Laboratory Information System. The equations for the calculation of reference values were obtained for boys and girls. The two bone markers markedly varied according to age, sex and pubertal stage with females displaying higher values during Tanner stages II and III and males during stages III and IV. ConclusionsThe application of a novel statistical approach provided reference curves for CTX-1 and BAP. This method, moreover, could be applied in pediatrics to obtain reference intervals for other biomarkers.

Sclerostin and DKK-1: two important regulators of bone metabolism in HIV-infected youths.

Reduced bone mineral density (BMD) and altered bone metabolism are common findings in HIV-infected patients. Increased bone formation has been described both in HIV-infected adults and children. Wnt ligands promote bone formation by stimulating osteoblast differentiation and their survival. Sclerostin and dickkopf factor 1 (DKK-1), Wnt antagonists, are important negative regulators of bone formation. We studied 86 HIV-infected patients whose ages ranged from 5.7 to 27.9 years. Patients were all on antiretroviral therapy, but seven who were naïve to treatment. Bone alkaline phosphatase (BAP), sclerostin, and DKK-1 were measured in serum by enzyme immunoassay. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine and in the whole skeleton. Biochemical indexes were also measured in 143 healthy controls (age range 4.5-27.4 years). HIV-infected patients had lower than normal BMD (spine P < 0.005, and whole skeleton P < 0.03). BAP measurements were significantly higher in HIV-infected patients than controls (P ≤ 0.05). Sclerostin and DKK-1 concentrations were markedly lower than in controls (P ≤ 0.0006, and P ≤ 0.03, respectively). The serum concentration of both analytes of patients naïve to antiretroviral treatment was not different from that of treated patients. No correlations were found between sclerostin, DKK-1, and bone mineral measurements. Our data confirm the alteration of bone metabolism pathways in HIV-infected individuals. The lower concentration of Wnt antagonists is consistent with the increased bone formation markers.

Inter-method variability in bone alkaline phosphatase measurement: Clinical impact on the management of dialysis patients

BackgroundBone-specific alkaline phosphatase (BAP) is now recommended to assess bone turnover in hemodialysis (HD) patients. However, little is known about potential variability between methods available to measure BAP. MethodsWe measured BAP in 76 HD patients with six different assays (Beckman-Coulter Ostase IRMA, Beckman-Coulter Ostase Access, IDS iSYS Ostase, IDS Ostase enzyme immunoassay, DiaSorin Liaison Ostase and Quidel MicroVue BAP). ResultsWe observed a high correlation between all the assays ranging from 0.9948 (IDS iSYS vs. IDS EIA) to 0.9215 (DiaSorin Liaison vs. Quidel MicroVue). However, using the regression equations, the equivalent concentration of a Beckman-Coulter Access value of 10μg/L can range from 7.7 to 14.4μg/L and of 20μg/L can range from 16.9 to 27.9μg/L with other assays. According to Beckman-Coulter Access, 13%, 50% and 37% of the patients presented BAP values ≤10, between 10 and 20 and ≥20μg/L, respectively. Discrepancies are observed when other assays are used (concordance from 10 to 100%). ConclusionsAnalytical problems leading to inter-method variation should be overcome to improve the usefulness of this marker in clinical practice. According to correlation results, recalibration of BAP assays is necessary but should not be a major issue.

P-0264 Carboxy-Terminal Telopeptide of Type I Collagene and Tartrate-Resistant Acid Posphatase Measurement in Patients with Colorectal Cancer and Bone Metastases

ABSTRACT Introduction Despite significant advances in detection and treatment, colorectal cancer (CRC) still remains one of the most prevalent cancers, and one of the leading causes of mortality due to malignancy. In patients with stage I-II CRC surgical resection usually represents the sole treatment, while in those with metastasized tumor (stage IV) any therapy is rarely successful. Unfortunately, up to 60% of patients with CRC undergoing primary surgery with curative intention die from metastatic disease. Thus, occult tumor cells, not detected preoperatively, likely colonize and remain vital in different tissues of these patients, such as lymph nodes, blood, and bone marrow. Usually, CRC metastasizes to the liver and lungs more frequently than to bone. Isolated bone metastasis (BM) is considered truly rare, but it has been observed that the improved survival for patients with metastatic CRC following expanded treatment options is associate with an increased incidence of BMs. Because metastases in uncommon sites often indicates the terminal phase of CRC, clinicians should be more vigilant about possible BMs. For this purpose, several serum biomarkers have been tested for early detection of BMs, such as carboxy-terminal telopeptide of type I collagen (ICTP), a cross-link product of collagen I degradation, and tartrate-resistant acid phosphatase 5b (TRACP), specifically derived from osteoclasts. Recent studies showed that TRACP activity and ICTP were increased in up to 90% of patients with breast cancer and BM. The aim of this study was to evaluate the usefulness of TRACP, ICTP, and bone alkaline phosphatase (BAP) measurements in patients with CRC and BM. Methods Fourteen patients (9 men, 5 women, mean age 56.1±4.8, range 49-63 years) with CRC and confirmed BMs (cases), and a group of 15 age- and gender matched (10 men, 4 women, age 57.1±4.9 years, p=0.08) patients (controls) without BM (negative F-18 FDG PET/CT) underwent serum TRACP, ICTP, and BAP measurements. Written informed consent was obtained from all the participants. TRACP and BAP were measured by two-site enzyme-linked immunosorbent assay (ELISA), while ICTP was measured by commercially available radioimmunoassay. The sensitivity and specificity of serum TRACP, ICTP, and BAP as a marker for BM were estimated by receiver operator characteristic (ROC) curves. Results The mean levels of TRACP, ICTP, and BAP (cases vs. controls) were: 5.9±1.6 vs. 4.8±1.3 U/L (95% CI 0.11-2.11, p=0.08), 6.9±1.4 vs. 5.9±1.3 U/L (95% CI 0.94-3.04, p=0.0003), and 82.6±18.2 vs. 79.3±16.2 (95% CI 9.81-16.39, p=0.59). ROC analysis established a cutoff value for ICTP of 4.51 U/mL to identify patients with extensive BM with a specificity of 97% and a sensitivity of 92% (area under the curve=0.97; 95% CI=0.95-0.98). A strong relationship was found only between TRACP and ICTP (R=0.95, p Conclusion Serum ICTP is a useful diagnostic marker in the detection of BMs in patients with CRC, more accurate than TRACP and BAP.

Evaluation of the IDS-iSYS Bone Alkaline Phosphatase (BAP) assay

Evaluation of the IDS-iSYS Bone Alkaline Phosphatase (BAP) assay

Efficacy of ONO-5334, a cathepsin K inhibitor, on bone mass and strength in ovariectomized cynomolgus monkeys

Efficacy of ONO-5334, a cathepsin K inhibitor, on bone mass and strength in ovariectomized cynomolgus monkeys

Analytical validation of serum bone alkaline phosphatase (BAP OSTASE) on Liaison

The goal of this study was to validate the DiaSorin Liaison BAP OSTASE, a new method for measurement of bone alkaline phosphatase (BAP), and to compare this method with the Beckman-Coulter Access Ostase. We also wanted to establish the reference range for BAP in adults and children. We determined the precision, functional sensitivity, recovery, linearity and measurement uncertainty, accuracy profile and beta-expectation limits. We defined an adult reference interval using individuals with 25-OH vitamin D >80 nmol/L, parathormone <58 ng/L, and normal calcium, phosphorous and estimated glomerular filtration rate. Each adult subclass (men/non-menopausal women/menopause women) contained 120 individuals. We also determined the 2.5th and 97.5th percentiles from a population of 450 children, stratified according to age and gender. The results of the validation showed: precision <6%, functional sensitivity <0.74 microg/L, mean recovery 98.8+/-4.2% and good linearity. Relative uncertainty ranged from 9.0% to 12.9%, and the risk of one result falling out of the +/-15% acceptance limits was <5% for concentrations between 7 and 94 microg/L. The Bland-Altman plot showed no systematic bias between the two methods. In adults, we did not find any statistical difference between the different subclasses. The upper limit of normality observed in the entire population (n=360) was 21.3 microg/L (90% CI: 18.3-24.2 microg/L). The Liaison BAP OSTASE is a robust method, and is completely validated between 7 and 93 microg/L: in this range, 95% of the values obtained will be within +/-15% of the true value.

Joint dependent concentrations of bone alkaline phosphatase in serum and synovial fluids of horses with osteochondral injury: an analytical and clinical validation

Validate use of a commercially available immunoassay for measurement of bone alkaline phosphatase (BAP) in equine serum and synovial fluid (SF), and investigate the effects of osteochondral (OC) injury in horses on BAP concentrations in serum and SF. SF was collected from 37 joints of 34 Thoroughbred (TB) racehorses undergoing arthroscopic surgery for the removal of OC fragments from either the carpal joints (n=18) or the metacarpo-/metatarsophalangeal (MP) joints (n=19). SF was also obtained from 52 joints of 16 normal TB horses, collected bilaterally from carpal joints of 10 horses (n=40), and MP joints of six horses (n=12). Blood was obtained from all 50 horses. A commercially available immunoassay was validated and subsequently used to determine equine serum and SF BAP concentrations. Correlations to radiographic and arthroscopic scores were assessed. BAP concentrations were significantly lower in serum from horses with OC injury in their carpal or MP joints than in serum from normal horses. SF BAP concentrations in normal and OC injured carpal joints were significantly higher than MP joints. BAP concentrations were significantly higher in SF from OC injured carpal joints than normal. BAP concentrations were affected by joint sampled, with age having a significant interaction. Concentrations of BAP in the serum (<30U/L), SF (>22U/L) and a ratio of SF to serum > or = 0.5 were predictive of OC injury. Radiographic and arthroscopic scores significantly correlated with serum BAP concentrations, and SF:serum BAP correlated with arthroscopic scores. Determination of serum and SF BAP concentrations may be beneficial in the investigation of early joint injury. Joint and injury dependent differences in BAP concentrations allowed the estimation of predictive value for identifying OC injury.

Measurement of bone alkaline phosphatase and relative study with osteosarcoma

The objective of this paper is to explore the value of bone alkaline phosphatase (BALP) for diagnosing osteosarcoma, evaluating the effect of the chemotherapy, judging the prognosis and supervising the relapse and metastasis. The immunoassay was used to check the BALP of the blood serum that was from 42 primary osteosarcoma patients. Alkaline phosphatase (ALP) in blood serum was checked with auto biochemistry equipment. The biopsy tissue and the lesion resected in operation were treated with pathology and histological response was counted. The patients were followed up from five months to 49 months with an average of 24.3 months. Eighteen cases relapsed and transferred, among which, 16 of them were dead, and others were survival to the end of the follow-up. BALP was more sensitive than ALP in diagnosing osteosarcoma (P = 0.015). Fifteen cases decreased to normal value in ALP after preoperative chemotherapy, and 34 cases decreased in BALP. Both ALP and BALP in all cases decreased to normal value in post-operative. There was significant difference in positive correlation between the decrease of BALP and the increase of histological response (P = 0.001, r = 0.642). In the follow-up, there was significant difference in BALP between the group of relapse and transfer and the group of free disease survival (P = 0.000). As a check marker in blood serum, BALP, reflecting the process of ossification, has a higher sensitivity than ALP. It has applied value in the diagnosis of osteosarcoma, reflection of the effect of chemotherapy and forecast the prognosis.

Is deoxypyridinoline a good resorption marker to detect osteopenia in phenylketonuria?

Objectives: To evaluate deoxypyridinoline as a resorption marker in phenylketonuria (PKU) and to search for a relationship between deoxypyridinoline, calcium/creatinine index (Ca/Cr I), osteocalcin and bone alkaline phosphatase (BAP). Methods: This was a transversal analytical study of 46 PKU patients [17.5 (4–38) years]. Deoxypyridinoline and osteocalcin were measured with a chemiluminescent assay and BAP was measured with an immunoradiometric assay. Results: Deoxypyridinoline was significantly increased in patients aged 7–14 and >18 years old, being associated with age ( r = −0.724, P < 0.001). Adult patients showed significantly higher Ca/Cr I, which correlates with Phe values for the year prior to the study ( P = 0.014). Serum BAP was significantly increased in pediatric patients (9–13 years), while it was decreased in adult patients ( P = 0.003). Decreased osteocalcin levels were found in patients >15 years ( P = 0.028). Altered deoxypyridinoline and BAP values were related ( P = 0.042). Conclusion: PKU patients excreted increased D-Pyr, suggesting high bone resorption. Bone formation seems active in childhood but deteriorates in adult PKU patients. Periodic measurement of D-Pyr and BAP may be useful in the prevention of osteopenia in PKU patients.

A study of bone turnover markers in prepubertal children with phenylketonuria.

To investigate the effect of low-phenylalanine diets onbone mineralisation status, we compared biochemicalbone formation and resorption markers in prepubertalchildren with phenylketonuria with those of age-mat-ched healthy controls.Dietary phenylalanine (Phe) restriction is the onlyknown strategy of preventing neurological impairmentand mental retardation in patients with phenylketonuria(PKU). In general, most phenylketonuric patients on alow-Phe diet can achieve normal growth and intellectualdevelopment. It is suggested, however, that this form ofdiet may influence bone metabolism, especially inchildhood and adolescence when growth and boneturnover are at their most intensive. Some authors havedescribed decreased bone mineral density and osteope-nia in patients suffering from PKU [1, 2, 3,5].Measurements of bone mineral density (BMD) reflectonly bone mineral status but not the dynamics of boneturnover. Non-invasive biochemical markers whichshow global skeletal activity have lately been developedand validated for the assessment of bone formation andbone resorption processes. Among them, osteocalcin(OC), bone alkaline phosphatase (BALP) and collagentype 1 cross-linked C-telopeptide (CTX) are consideredto be clinically useful. Recently, the novel cytokineosteoprotegerin (OPG), belonging to the tumournecrosis factor receptor family has been established asan endogenous inhibitor of osteoclastogenesis andresorption processes.Our study population consisted of 37 childrenwith PKU under surveillance at the Department ofPaediatrics at the Institute of Mother and Child inWarsaw. Patients were divided into two groups. Thosein group A (n =12; median age 4.5 years; range 3–10years) followed their therapeutic diet strictly and hadmean serum Phe concentrations close to the referencerange (189.4±64.2 lmol/l) and those in group B(n =25; median age 6.0 years; range 3–10 years) did notadhere to their diet and had increased Phe concentra-tions (649.2±140.6 lmol/l). The mean serum Pheconcentration was calculated for the last 3 years of thelife of each patient. Children with PKU were fed with anaminoacid mixture PAM, Milupa-PKU 2 or Phenyl-free. These patients have normal values for calcium andphosphate. Healthy children sent to our laboratory forroutine analytical control (n =27; median age 5.9 years;range 4–9 years) were the reference group. The wholegroup of investigated children was ethnically homoge-nous. Venous blood samples were collected after anovernight fast, centrifuged and serum levels of Phe,calcium and phosphate were determined. Remainingserum samples were frozen and collected for measure-ment of BALP, OC, CTX and OPG. Phe was assayedfluorometrically according to McCaman and Robbins;calcium and phosphate by standard procedures with aCobas Integra analyser (Roche, Switzerland). Serum OCand CTX were measured by immuno-enzymatic ELISAassays (Osteometer, Denmark). For determination ofBALP, the Alkphase-B kit from Metra Biosystems(USA) and for OPG, the kit from Biomedica (Austria)were used. The differences were evaluated by ANOVAwith Bonferroni correction. The significance was set atP <0.05.We observed lower levels of bone formation andbone resorption markers in group A than in group B,but these differences are not statistically significant(Table 1). However, OC, CTX and OPG concentrationswere significantly lower in both groups of PKU childrenin comparison to the healthy age-matched controls.There are only a few papers presenting values of boneturnover markers in PKU subjects. Perez-Duenas et al.[6] observed the same levels of OC and BALP in a groupof younger patients and significantly lower serum BALP

Clinical observations with a new specific assay for bone alkaline phosphatase: a cross-sectional study in osteoporotic and pagetic subjects and a longitudinal evaluation of the response to ovariectomy, estrogens, and bisphosphonates.

The purpose of this study was to examine the serum levels of bone alkaline phosphatase (BALP) measured with a new assay in normal and in osteoporotic women, and to evaluate prospectively its responsiveness to changes of bone metabolism. The following groups of subjects were studied: (1) 95 healthy women (44-75 years) (22 pre- and 73 postmenopausal) and 35 osteoporotic women [vertebral bone mineral density (BMD) more than 2.5 SD below the normal adult mean]; (2) 10 women (44-50 years) ovariectomized (OVX) for benign uterine diseases, examined before and 12 months after surgery; (3) 16 OVX women (36-54 years), examined before and after 12 months of transdermal estrogen replacement therapy (50 microg/day); (4) 12 previously untreated pagetic patients (4 women and 8 men, 50-80 years), examined before and 3 months after the I.V. administration of clodronate (600 mg) or alendronate (5 mg) for 2 consecutive days. The median BALP value was 11.6 U/liter (25-75th percentiles: 10.5-12. 7; range 7.7-19.3) in healthy premenopausal (PreMP) women and significantly higher (median: 16.8 U/liter; 25-75th percentile: 13. 8-21.8; P < 0.01) in postmenopausal (PostMP) women. There was a clear age-related increase in normal subjects (r = 0.43; P < 0.001). In the osteoporotic group, BALP levels, as well as other biochemical parameters of bone turnover, were not significantly different from those of normal women when adjusted for age. In OVX women, BALP levels showed a marked increase 12 months after surgery (median: 113%; 25-75th percentile: 87-139%), significantly higher than the increase of total ALP (median: 43%; 25-75th percentile: 25-66%; P < 0.001), and similar to the increases of serum osteocalcin and urinary hydroxyproline. Transdermal estrogen treatment prevented the BALP increase, even if no reduction was observed; total ALP showed a similar behavior. The basal levels of BALP were significantly elevated in pagetic patients (median: 91 U/liter; range 18-610 U/liter) and correlated to the scintigraphic extent of the disease (r = 0.76; P < 0.01). Three months after the I.V. administration of bisphosphonates, the decrease of BALP was more marked than that of total ALP (median: -54% versus -41%; P < 0.05). In conclusion, these results suggest that BALP measurement with this immunoassay may be clinically useful, and more sensitive than total ALP, in the assessment of bone turnover during changes of the estrogen status as well as in monitoring the effects of treatments that modify the metabolic activity of the skeleton.

Bone Alkaline Phosphatase in Paget's Disease

The measurement of bone proteins and peptides and their derived products has been very useful in the diagnosis and management of patients with skeletal disease. This group of assays includes alkaline phosphatase (AP) and bone Gla protein (BGP). We here describe the comparison of a new immunoassay that is specific for bone alkaline phosphatase (BAP) to measurements of total alkaline phosphatase (TAP) and BGP in Paget's disease. In our studies, we demonstrated that BAP was increased in the serum of patients with Paget's disease. Comparisons with the other measurements revealed that BAP correlated better with total AP (r = 0.92) than with BGP (r = 0.51); the lowest correlation occurred between BGP and total AP (r = 0.26). In patients with liver disease, the BAP was indistinguishable from normal whereas the TAP was elevated. These studies indicate that BAP assesses different aspects of bone cell function than BGP in Paget's disease. This discordancy also exists between BGP and total serum AP activity. BAP measurements by immunoassay offer a novel method of assessing skeletal status. Thus, the information that measurement of different bone-specific proteins provides should be separately useful in assessing the skeleton for a variety of metabolic bone diseases.

Biochemical Markers of Bone Turnover for the Clinical Assessment of Metabolic Bone Disease

There is not yet an ideal marker of bone formation, but circulating BGP is the most satisfactory at present. New developments include the use of sheep BGP64 and human BGP85 as an immunogen and monoclonal antibodies, which may recognize fragments of BGP released during resorption. The specific measurement of bone alkaline phosphatase and the assay of procollagen fragments and of other noncollagenous bone-related proteins will allow a more precise assessment of the complex osteoblastic functions in normal and pathologic conditions. Finding a sensitive and specific marker of resorption is a challenge because all constituents of bone matrix are likely to be degraded into minute peptides during osteoclastic bone resorption. The measurement of pyridinium crosslinks and possibly of tartrate-resistant acid phosphate by a bone-specific monoclonal antibody are the most tangible improvements in this area. These markers need to be validated by comparison with data obtained by direct measurement of bone turnover on iliac crest biopsy. It should be remembered, however, that circulating markers reflect the overall activity of the whole skeleton, including the cortical, subcortical, and trabecular envelopes, which have different remodeling rates in normal and abnormal states. A circulating marker will not detect a specific defect of the cellular activity of one compartment of bone if the summated turnover of the skeleton is unchanged. Conversely, bone histomorphometry is limited to a small area of the trabecular envelope but allows detection of a specific defect at the cellular level. These differences should be kept in mind, as there is growing evidence that, for example, bone mass and bone turnover of osteoporotic patients before and during treatment vary in different appendicular/axial and cortical/trabecular compartments. Finally, a single marker might be valuable in some diseases and not in others (such as serum BGP in Paget's disease of bone). Despite these difficulties, significant advances have been made in the last few years in the bone marker field. In the future, the development of a battery of several bone-specific markers that indicate various aspects of the complex mechanisms of bone formation, resorption, and mineralization is likely to provide new tools for the diagnosis and management of bone diseases.