Short-Term Risedronate Treatment in Postmenopausal Women: Effects on Biochemical Markers of Bone Turnover

The development of new biochemical markers has made it possible to assess the effects of therapeutic agents on bone turnover more rapidly and precisely. In this early phase II study, we analyzed the effects of short-term, high-dose treatment with risedronate, a potent pyridinyl bisphosphonate, on markers of bone resorption and formation. Resorption markers included urinary free deoxypyridinoline (D-Pyr) crosslinks, N-terminal telopeptide (NTx) and C-terminal telopeptide (CTx) type I collagen crosslinks. Bone formation markers included osteocalcin (OC), bone-specific alkaline phosphatase (BSAP) and the C-terminal peptide of type I procollagen (PICP). All three resorption markers showed rapid, significant (p<0.05) decreases from baseline following daily administration of 30 mg risedronate for 2 weeks. The mean decreases at 2 weeks were 28% for D-Pyr, 61% for NTx and 73% for CTx, respectively. Over the next 10 weeks after treatment, D-Pyr approached baseline while NTx and CTx remained well below baseline values. The markers of bone formation showed little change during therapy but decreased significantly at 4–10 weeks after therapy – an expected outcome of bisphosphonate therapy. Moreover, there was a significant correlation between the early effects on bone resorption markers and the delayed effects on formation markers. This study demonstrates that the approved dose of risedonate (30 mg/day) for Paget”s disease is effective at decreasing bone turnover after 2 weeks of treatment, as observed by the sensitive response of bone turnover markers. Received: 18 August 1999 / Accepted: 18 January 2000     

Clinical usefulness of cross-linked N-telopeptide of type I collagen (NTx) as a bone metastatic marker in patients with prostate cancer--comparison with serum PICP, PINP and ICTP

Type I collagen cross-linked N-telopeptide (NTx) in urine, the degraded form of type I collagen cross-linked in bone, has been evaluated as a marker of bone resorption. In this study, the clinical usefulness of NTx as a marker of bone metastasis of prostate cancer was compared with that the carboxyterminal propeptide of type I procollagen (PICP), the aminoterminal propeptide of type I procollagen (PINP), and the pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) in serum. We assessed 37 cases of prostatic cancer in which the diagnosis had been confirmed pathologically. The patients were 15 patients with prostatic cancer with bone metastasis (before treatment or during a relapse) (Group 1); 11 patients, with bone metastasis, but for whom treatment was effective and condition had stabilized (Group 2); and 11 patients, with localized prostatic cancer and no evidence of bone metastasis (Group 3). The serum PICP, PINP, and ICTP levels and concentration of NTx in urine were compared among the three groups with the Mann-Whitney U test, with p values less than 0.05 considered significant. Urine NTx concentrations in Groups 1, 2 and 3 were 539.3 +/- 202.9, 160.6 +/- 97.6 and 48.6 +/- 7.6 nMBCE/mMCr, respectively. The differences between the Group 1 and Group 2 and between Group 1 and Group 3 were significant (p < 0.01 and p < 0.001). The differences between Group 1 and Group 3 and between Group 2 and Group 3 were significant for serum PICP, PINP and ICTP concentrations (p < 0.05). The correlation coefficient between urine NTx and each serum bone metabolic marker was 0.8 for PICP, 0.4 for PINP and 0.5 for ICTP. These bone metabolic markers are promising clinical markers of bone metastatic and may be useful for prediction of therapeutic efficacy and recurrence in bone and quantification of the extent of bone metastates.     

Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen as a useful marker for monitoring metastatic bone activity in men with prostate cancer

PURPOSE: We investigated the clinical usefulness of measuring the serum concentrations of pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen (PICP) as markers for monitoring metastatic bone activity in patients with prostate cancer. MATERIALS AND METHODS: Serum levels of ICTP, PICP, alkaline phosphatase, prostatic acid phosphatase and prostate specific antigen (PSA) were analyzed in 104 untreated patients with prostate cancer, including 62 with and 42 without bone metastasis. Serial measurements of ICTP, PICP and PSA were performed during hormonal therapy in 35 of 62 prostate cancer patients with bone metastasis. RESULTS: Serum levels of all markers except prostatic acid phosphatase were significantly higher with than without bone metastasis. The median values of each marker increased according to the extent of bone metastasis. Serial ICTP, PICP and PSA in 19 patients with a partial response or no change in bone scans demonstrated a downward trend after treatment, while in 16 with progression they showed an upward trend after treatment. The rate of detecting bone metastasis and progression using ICTP were highest compared with other markers based on the percent clinical effectiveness and receiver operating characteristic curves. CONCLUSIONS: Measuring serum ICTP may be useful for detecting bone metastasis and prostate cancer progression, and may augment PSA and bone scan monitoring of metastatic bone activity.     

Differences in the Capacity of Several Biochemical Bone Markers to Assess High Bone Turnover in Early Menopause and Response to Alendronate Therapy

We measured bone mineral density (BMD), four markers of bone formation [bone alkaline phosphatase (bAP), osteocalcin (Oc), N- and C-terminal propeptide of type I procollagen (PINP and PICP respectively)] and five markers of bone resorption [serum C-terminal telopeptide of type I collagen (CTx), urinary CTx, N-terminal cross-linked telopeptide (NTx), free and total deoxypyridinoline (fDpd and tDpd respectively)] in 28 healthy premenopausal women (45.7 ± 3.0 years), 15 early (<7 years) healthy menopausal women (53.8 ± 3.1 years) and 20 osteoporotic women (65.3 ± 8.2 years). Bone markers and BMD were also measured in the osteoporotic women 4.1 ± 0.2 and 12.6 ± 1.2 months after the beginning of alendronate therapy (Fosamax, 10 mg/day) respectively (BMD in 16/20). We calculated the intra-individual coefficient of variation (iCV) and the least significant change (LSC) for each bone marker from a subset of 9 healthy premenopausal women (32 ± 5 years) who had a first and a second morning void urine collection (FMV and SMV respectively) and a blood sample on 4 nonconsecutive days (mean interval 14 ± 3 days). None of the bone markers was correlated with BMD (except p= 0.043 between serum Oc and hip BMD). All markers, except fDpd, were increased significantly in early menopausal women when compared with the premenopausal group. Serum CTx presented the highest increase at menopause (+67.8%) and identified the highest rate (11/15) of early menopausal women with bone turnover above the premenopausal range. The iCVs for bone formation markers (7.2–14.4%) were lower than those for bone resorption markers (14.6–22.3%). The iCVs obtained on FMV and SMV were not different. The decrease after 4 months of alendronate was significant for each bone marker but variable from one marker to another. Serum CTx showed the largest decrease (70.8%) and identified the highest number of biologically responding patients (change >LSC; n= 17/20). A significant change in serum CTx after 4 months of alendronate was the best predictor of a significant gain in spine BMD (i.e., ≥27 mg/cm²) after 1 year of therapy, allowing 15 of 16 patients (94%) to be classified correctly (one false-positive). Urinary NTx/Cr was the second best predictor. Despite a moderately high iCV (20.6%), serum CTx appeared the most effective of the markers tested and could be of interest for the detection of high bone turnover and the longitudinal monitoring of alendronate therapy in the individual patient. It must be stressed that serum PINP and urinary NTx and tDpd compared very similarly with serum CTx for monitoring alendronate therapy. Received: 12 April 1999 / Accepted: 13 September 1999     

Bone ultrasonometry and turnover markers in primary hyperparathyroidism

Quantitative ultrasound (QUS) of bone and new markers of bone remodeling have been poorly investigated in mild primary hyperparathyroidism (PHPT). In this study 26 patients (20 females and 6 males) were evaluated. BUA and SOS were measured by QUS at the heel. Markers of bone remodeling assessed were bone alkaline phosphatase (BAP), osteocalcin (OC), procollagen type I N- and C-terminal propeptides (PINP et PICP), and procollagen type I C-terminal telopeptide in blood and urine (ICTP and CTX). Bone mineral density (BMD) was measured at the lumbar spine (LS), femoral neck (FN), and Ward's triangle (WT). The control group comprised 35 sex- and age-matched subjects. The statistically significant variables between the two groups were (P < 0.05) BUA, BMD_LS, BMD_FN, BMD_WT, BAP, and OC. Corresponding z-scores were −0.55 ± 0.75, −0.66 ± 0.77, −0.66 ± 0.71, −0.67 ± 0.52, 1.87 ± 3.87, and 1.93 ± 3.53, respectively. Although PICP and PINP levels were higher in PHPT patients as compared with controls, the difference was not significant. Several markers of bone turnover were moderately correlated with both QUS (r =−0.39 to −0.55) and BMD (r =−0.48 to 0.63). In conclusion QUS seems to be a relevant tool in the assessment of bone status for patients with mild PHPT. Received: 1 October 1998 / Accepted: 1 July 1999     

Bone density change and biochemical indices of skeletal turnover

Although biochemical markers of skeletal turnover cannot replace bone density scanning for the diagnosis of osteoporosis, it is thought that they may help add to prediction of fracture risk and help determine adequacy of osteoporosis therapy. Nevertheless, whether biochemical markers in the serum or urine can predict individual rates of bone loss in the spine or hip region is unknown. We studied a heterogeneous group of women (n=81) who were premenopausal, untreated postmenopausal, and estrogentreated postmenopausal with baseline determination of body mass index (BMI), calcium intake, biochemical measurements, and serial bone densitometry over 3 years. Serum assays included bone Gla protein (BGP), total and bonespecific specific included bone Gla protein (BGP), total and bone-specific alkaline phosphatase (AP, BSAP), carboxyterminal propeptide of type I procollagen (PICP), carboxyterminal telopeptide of type I collagen (ICTP) and tartrate-resistant acid phosphatase (TRAP). Urine assays included hydroxyproline (OHP), calcium, total pyridinoline, and total deoxypyridinoline. Individual biochemical markers and calcium intake were modestly correlated with bone density changes but were inconsistent regarding the spine versus the hip. All of the formation variables were significantly correlated to spine density change (r=−0.24 to −0.49) whereas the only resorption variable that correlated was urine OHp/Cr (r=−0.31). The only formation variable that correlated with hip density change was serum PICP whereas all of the resorption variables except serum TRAP were correlated (r=−0.23 to −0.35). “High turnover” individuals were defined as those with levels of biochemical variables at least 1 SD above the mean young normal for each variable. Higher bone loss rates were seen in this group for several of the turnover markers compared with bone loss rates in all other individuals. However, the sensitivity of this “high turnover” status for identifying high bone losers did not exceed 60% for any of the variables. In untreated postmenopausal women, a model using urine OHp, serum ICTP, serum BSAP, and calcium intake was able to predict 42% of the variance of change in BMD of the lumbar spine. A model using BMI, serum ICTP, and serum BGP could predict 32% of the variance of change in BMD of the femoral neck. No combination of markers could predict variance in bone density change at either site in estrogenized women (premenopausal and estrogen-treated postmenopausal). We conclude that measuring individual serum and urine markers of bone turnover cannot accurately predict bone loss rates in the spine and hip; however, combinations of demographic and biochemical variables could predict some of the variance in untreated postmenopausal women. Biochemical markers cannot replace serial bone densitometry for accurate determination of change in bone mass at the most clinically relevant sites.     

Serial markers of bone turnover in men with metastatic prostate cancer treated with zoledronic Acid for detection of bone metastases progression

OBJECTIVES: This study assessed the usefulness of serial measurements of bone turnover markers in men with metastatic prostate cancer treated with zoledronic acid to detect disease progression. METHODS: Serum measurements of total alkaline phosphatase (tALP), bone-specific alkaline phosphatase (bALP), cross-linked N-terminal (NTx) and cross-linked C-terminal (CTx) telopeptides of type I collagen, amino-terminal procollagen propeptides of type I collagen (PINP), C-terminal telopeptides of type I collagen (ICTP), and prostate-specific antigen (PSA) were performed in 77 prostate cancer patients suffering from bone metastases and treated with zoledronic acid up to 15 mo. Fifty patients were with and 27 patients without objective evidence of metastatic bone progression during the administration of zoledronic acid. RESULTS: The baseline bone marker concentrations were not significantly different between the groups. After administration of zoledronic acid all bone markers except of ICTP decreased compared with baseline. CTx showed the greatest decrease. In patients with metastatic bone progression PINP, tALP, bALP, and ICTP were significantly higher at weeks 24, 36, 48, and 60 after starting treatment with zoledronic acid compared with patients without progression. In addition to the information of prostate-specific antigen as a monitoring parameter, the bone formation marker showed a better distinction between patients with and without disease progression. CONCLUSIONS: Selected bone turnover markers provide valuable information regarding progression of bone metastasis in men with metastatic prostate cancer under bisphosphonate therapy. The clinical impact should be confirmed in prospective randomised studies.     

The effects of brisk walking on markers of bone and calcium metabolism in postmenopausal women

Weight-bearing exercise has been shown to maintain or increase bone mass in younger as well as older individuals but the mechanisms by which mechanical loading affects bone metabolism are not known in detail. Twelve postmenopausal women participated in a single bout of brisk walking (50% of VO_{2 max}) for 90 minuttes. Calciotropic hormones and markers of type I collagen formation (PICP) and degradation (ICTP) were measured before the exercise, and 1, 24, and 72 hours following the exercise. Total body bone mineral content (BMC) and density (BMD) were measured by dual energy X-ray absorptiometry (DXA). Brisk walking did not induce any significant changes in the concentrations of ionized calcium, parathyroid hormone (PTH), calcitonin, or osteocalcin. A significant increase of PICP was noted 24 and 72 hours (P<0.01) after exertion and a significant decrease in the concentration of serum ICTP at 1 hour (P<0.05) was followed by an increase at 72 hours (P<0.001). There was no significant difference between the increases in the concentrations of PICP and ICTP at 72 hours. Strong inverse correlations between the basal levels of PTH and BMD (r=−0.78;P<0.01) as well as between osteocalcin and BMD (r=−0.83;P<0.01) were noticed. The changes in serum levels of bone collagen markers indicate an altered bone collagen turnover due to this moderate endurance exercise. The results also support the fact that serum levels of PTH as well as those of osteocalcin are associated with total body BMD in postmenopausal women.     

The serum level of the amino-terminal propeptide of type I procollagen is a sensitive marker for prostate cancer metastasis to bone

OBJECTIVE: To assess the level of a bone-formation marker, the amino-terminal propeptide of type I procollagen (PINP), for its utility in indicating bone metastasis in patients with prostate cancer. PATIENTS AND METHODS: Several bone formation markers, i.e. PINP, the carboxy-terminal propeptide of type I procollagen (PICP), bone-specific alkaline phosphatase (BALP), and bone Gla protein (BGP), a bone resorption marker (pyridinoline cross-linked carboxy-terminal telopeptide, ICTP), and prostate specific antigen (PSA) were measured in 40 patients without and 25 patients with bone metastasis. No patient had undergone previous treatment, except for six who developed bone metastasis while undergoing hormone therapy. RESULTS: All markers except BGP were significantly higher in patients with bone metastasis than in those without. The levels of PINP correlated best with the extent of disease, although the levels of PSA, BALP and ICTP also correlated well. While PINP had the largest area under the receiver-operator characteristic curve, PSA, BALP and ICTP also produced useful curves. CONCLUSION: The bone formation marker PINP seems to be useful for discriminating patients with and without bone metastasis. PINP may help in the early and accurate diagnosis of bone metastasis in such patients.     

Evaluation of bone loss and the serum markers of bone metabolism in patients with hyperparathyroidism

Bone loss and the serum markers of bone metabolism were studied in 22 patients with primary hyperparathyroidism and 108 patients with renal hyperparathyroidism. The parameters of bone loss were bone mineral density in the distal radius and lumbar vertebrae, measured by dual energy X-ray absorptiometry, and bone mass index (GS/D) and the metacarpal index, in the second metacarpal bone, measured by the digital image processing method. Alkaline phosphatase (AIP), intact osteocalcin (OC), and the carboxyterminal propeptide of type I procollagen (PICP) were measured as serum markers of bone formation, while tartrate-resistant acid phsophatase (TRACP) and the carboxyterminal pyridinoline cross-linked telopeptide of type I collagen (ICTP) were measured as serum markers of bone resorption. Bone loss and elevated markers of bone metabolism were observed both in patients with skeletal symptoms and in those without. Furthermore, the decrease in the cortical bone mass was more predominant than that of the trabecular bone. As markers of bone formation, AIP and OC seemed to be more sensitive than PICP, and as markers of bone resorption, ICTP appeared to be more sensitive than TRACP. Thus, a close correlation was observed between bone loss and the markers of bone formation and resorption.     

Short-term effects of glucocorticoid therapy on biochemical markers of bone metabolism in Japanese patients: a prospective study

Glucocorticoid (GC) therapy induces rapid bone loss, but the early changes in calcium and bone metabolism in patients treated with GC have not been clarified. To investigate the changes in calcium and bone metabolism during the early stage of GC therapy, we analyzed various biochemical markers of bone metabolism. The serum levels of calcium (Ca), phosphorus, parathyroid hormone (PTH), osteocalcin (OC), bone alkaline phosphatase (BAP), and type I collagen cross-linked N-telopeptide (NTx), as well as the urinary levels of Ca, creatinine, and NTx, were measured on days 0, 3, 7, and 28 of GC therapy. The subjects were divided into the following four groups: 9 patients receiving pulse therapy (P), 18 patients receiving prednisolone (PSL) at doses ≥40 mg/day (H), 9 patients receiving PSL at doses ≥20 mg/day (M), and 11 patients receiving PSL at doses ≤10 mg/day (S). The serum OC level showed a marked decrease on day 3 of GC therapy (−41.2% ± 6.6%, P < 0.01), while the BAP level decreased gradually. Both serum and urinary NTx levels significantly increased on day 7 of GC therapy (9.9% ± 4.5%, P < 0.05, and 42.2% ± 10.6%, P < 0.01, respectively). Urinary Ca excretion was increased on day 3 of GC therapy and continued to increase until 4 weeks, while intact PTH showed an increase on day 3 and then remained constant until 4 weeks. In groups P and H, there were significant early changes in OC, BAP, NTx, and intact PTH levels, as well as urinary Ca excretion. Even a PSL dose of <10 mg/day caused a decrease in the serum OC level. In conclusion, the biochemical markers of Ca and bone metabolism showed different kinetics depending on the dose of GC, and it is important for patients on high-dose GC therapy to receive prophylaxis for bone loss from the start of GC treatment.     

Biochemical Markers as Predictors of Bone Mineral Density Changes After GnRH Agonist Treatment

To evaluate bone biochemical markers as predictors of the efficacy of a hormone replacement therapy (HRT), we studied the bone changes induced by the cessation and return of ovarian function in 28 patients treated for 6 months with a GnRH agonist. This model reproduced the effects observed in postmenopausal women with high bone turnover treated with HRT. At the end of the treatment, Z scores were 1.8 ± 0.3 for Crosslaps (CTx) and deoxypyridinoline (D-Pyr), and 1.1 ± 0.2 for bone alkaline phosphatase (B-ALP) and osteocalcin (OC). This indicated an imbalance in bone remodeling with a high bone resorption. Bone mineral density (BMD) fell by 4.2 ± 2.5%. The changes in BMD between the 6th and 12th months were 0.34 ± 2.24 and −1.73 ± 3.25% at the lumbar spine and the femoral neck, respectively. Biochemical markers except urinary calcium and hydroxyproline measured at 6 months were positively correlated with the BMD changes at the lumbar spine. After the resumption of menstruation, 13 of 28 women displayed positive spine BMD changes between the 6th and 12th months; in this group, bone biochemical markers measured at 6 months were significantly higher (P= 0.02). Stepwise regression analysis showed that the association of B-ALP and D-Pyr measured at 6 months explained 40% of BMD variance and the association of B-ALP, PTH, and estradiol 56%. We conclude that measuring individual biochemical bone markers can help to predict the bone effect of an increase in the circulating estradiol in women with ovarian deficiency. Received: 16 January 1997 / Accepted: 17 June 1997     

Collagen type I metabolism after bone surgery

This study follows the postoperative course of serum collagen type I metabolites in patients after uncomplicated implantation of a cemented total hip endoprothesis (TEP; n = 12, mean age: 69.3 years), a cemented hemiendoprothesis (HEP; n = 13, mean age 79.7 years), a dynamic condylar or hip screw (DCS/DHS; n = 12, mean age 75.1 years) and osteosynthetic treatment of a Weber B or C fracture (OS; n = 17, mean age 54.3 years). The course of the propeptide of human type I procollagen (PICP) as an anabolic marker as well as of I-carboxyterminal telopeptide (ICTP) as a catabolic marker of bone metabolism was characterized. Measurements were done preoperatively and weekly for 3 weeks after surgery. The concentrations of both markers increased and reached a maximum in the 2nd or 3rd week after surgery. However, the PICP values differed, depending on the kind of surgical intervention and the type of bone healing. Secondary fracture healing with formation of callus occurred in the DCS/DHS group, which developed the highest median PICP concentrations (initial 83 μ g/l, second week 337 μg/l; P < 0.001). In contrast, the primary bone healing in the OS group showed increasing ICTP but unchanged PICP concentrations. Patients in the cemented TEP and HEP groups as a kind of artificial bone healing had comparable concentrations. To consider the effective metabolism of collagen type I, the PICP/ICTP ratio was calculated. Although the median PICP and ICTP concentrations of the studied groups differed, the PICP/ICTP ratios were similar. In comparison to 54 young and healthy volunteers (median PICP/ICTP ratio: 37), the ratios of the studied groups were still normal but low (median ratios: < 20). This could be an effect of decreasing collagen type I metabolism with age. Although the results are in agreement with animal studies and histomorphometric investigations, the clinical use of PICP and ICTP determination as a tool for the detection of complicated bone healing is limited by the marked interindividual variability and the uncertain bone specificity. Received: 2 April 1998     

Variable efficacy of bone remodeling biochemical markers in the management of patients with Paget’s disease of bone treated with tiludronate

The aim of this work was to evaluate the response of different biochemical bone markers to tiludronate administration in Paget’s disease of bone. Ten patients (five men and five women), 56–77 years old (67 ± 6.5), were treated for 3 months with tiludronate tablets (400 mg/day). Bone formation markers: alkaline phosphatase (AP), bone alkaline phosphatase (bAP), osteocalcin (BGP), and procollagen I carboxyterminal propeptide (PICP) in serum; and bone resorption markers: serum cross-linked carboxyterminal telopeptides of type I collagen (ICTP), urinary hydroxyproline/creatinine (Hyp/Cr), pyridinoline/Cr (Pyr/Cr), and alpha-1 collagen chain products degradation (CrossLaps) were assessed. Samples were taken before and at monthly intervals for 3 months after treatment began. The results of the present work show that serum AP and bAP are sensitive and reliable biochemical markers of bone formation in the follow-up of tiludronate in this disease. Serum PICP shows less sensitivity than serum AP, and serum BGP is not indicated as biochemical marker in these types of studies. Urinary hydroxyproline seems to be the most reliable biochemical marker of bone resorption. More studies should be performed with urinary Pyr and CrossLaps determinations. Serum ICTP is not adequate for the follow-up of tiludronate treatment in Paget’s disease of bone.     

Levels of bone collagen markers in preterm infants: relation to antenatal glucocorticoid treatment

Although the beneficial effects of antenatally administered glucocorticoids are well documented, data on the potential of adverse consequences are limited. The objective of this study was to determine the effects of antenatally administered glucocorticoids on biochemical markers of bone metabolism of 55 preterm infants with a gestational age of 24–34 weeks who were enrolled in the study. Neonates were divided into two groups according to antenatal exposure to corticosteroids. There were no significant differences between the groups in clinical characteristics and anthropometric variables. We studied blood levels of osteocalcin (OC), carboxy-terminal propeptide of type I procollagen (PICP), and carboxy-terminal telopeptide of type I collagen (ICTP) at the time of delivery, on postnatal day 10, and at 2 and 4 months of life. Comparing the groups, we found statistically significant reduction in PICP levels at birth in corticosteroid-exposed neonates (P < 0.05). The levels of bone markers increased progressively on the first days of life. There were no significant differences between groups in bone markers at 10 days or at 2 and 4 months of life. We found no significant difference for bone markers between groups of infants exposed to single or repeated maternal corticosteroid treatments. In summary, antenatal glucocorticoid treatments are suggested to have a negative impact on fetal bone formation as reflected by low PICP levels at birth. However, this negative effect on bone markers seems to be a temporary effect that subsides on the first days of life and afterward.     

Leptin and bone turnover in monochorionic twins complicated by twin–twin transfusion syndrome

Introduction To test the hypothesis that the bone metabolism of a growth-restricted foetus is regulated by genetic, placental and/or foetal factors through leptin, we investigated the foetal bone turnover in monochorionic pregnancies complicated with or without twin–twin transfusion syndrome (TTTS). Methods Maternal and cord bloods were collected from gestational-age-matched monochorionic twins with (n = 15) and without (n = 15) TTTS. The samples were assayed for leptin, cross-linked carboxyl terminal telo-peptide (ICTP, a marker of bone resorption) and pro-peptide (PICP, a marker of bone formation) of type I collagen by radioimmunoassay (RIA). Results In the growth-restricted donor twin, the plasma concentration of leptin (P < 0.001), PICP (P < 0.001) was lower, while that of ICTP (P < 0.001) was higher than the recipient twin of the TTTS group. In contrast, leptin, PICP and ICTP were comparable in non-TTTS twins. In the recipient twin of TTTS and non-TTTS twins, leptin was positively associated with PICP (r = 0.73; n = 45, P < 0.001) and negatively with ICTP (r = −0.68; n = 45; P < 0.001). No such association was found between leptin and bone marker in the growth-restricted donor twin of the TTTS group. Conclusion Our data suggest that, in AGA twins, leptin maintains bone metabolism by inhibiting resorption and enhancing bone formation. In contrast, growth-restricted donor twins have high bone turnover and this does not seem to be due to leptin deficiency.     

Quantitative Ultrasound in the Assessment of Skeletal Status in Uremic Patients

Renal osteodystrophy (ROD) can be characterized by both high (HT) and low (LT) bone turnover states. Although bone biopsy remains the "gold standard" to diagnose ROD, noninvasive tools for the diagnosis and follow-up of such bone disease are desirable. Recently, ultrasound (US) techniques, proposed to assess skeletal status, have been shown to be correlated not only with bone density but also with bone quality. We have investigated 98 patients on chronic hemodyalisis (HD) and 98 healthy, sex- and age-matched subjects. Amplitude-dependent speed of sound (AD-SOS) and ultrasound bone profile score (UBPS) at phalanxes and speed of sound (SOS), broadband ultrasound attenuation (BUA), and a quantitative ultrasound index (QUI/stiffness) at the heel were performed in both groups. In all subjects intact parathyroid hormone (PTH), total alkaline phosphatase (T-ALP), bone isoenzyme alkaline phosphatase (B-ALP), and carboxy-terminal telopeptide of type I collagen (ICTP) were assessed. All US parameters were significantly lower in the hemodialysis group than in control subjects. Moreover, among US parameters only AD-SOS and UBPS showed a significant correlation with PTH, T-ALP, and B-ALP. Dialytic age showed a modest, but significant correlation only with US parameters at the phalanxes. On the basis of bone biochemical markers, we considered a group with high and a group with normal to low bone turnover. AD-SOS and UBPS, but not SOS, BUA, and stiffness were significantly (p < 0.01) lower in the high bone turnover than in low bone turnover group. Furthermore, in the high bone turnover group, parameters of the US phalanxes strongly correlated with B-ALP. Our results seem to demonstrate that US parameters are a useful tool in the assessment of skeletal status in patients on maintenance dialysis.     

Bone Modeling Indexes at Onset and During the First Year of Follow-Up in Insulin-Dependent Diabetic Children

Osteopenia has been described as a complication of insulin-dependent diabetes mellitus (IDDM). We measured bone modeling indexes during the first year of IDDM. At each time point the values obtained from diabetic children have been compared with those of control subjects. We selected 27 prepubertal children with IDDM (6.35 ± 2.16 years). We also enrolled 30 healthy prepubertal children of comparable age (5.85 ± 3.05 years). Height, height standard deviation scores, glycated haemoglobin (HbA_1C), basal c-peptide concentrations, insulin dose, serum concentrations of procollagen type I C-terminal propeptide (PICP), and collagen type I C-terminal telopeptide (ICTP) were measured at onset of IDDM and at 3, 6 and 12 months. ICTP was in the normal range at onset of IDDM and decreased during the follow-up to reach a significant difference compared to controls after 3, 6 and 12 months of insulin treatment (P < 0.04). PICP concentrations increased significantly at 3 months (P= 0.05) compared to onset. At 3 and 12 months PICP values were significantly higher than those of control children (P= 0.04). Correlations were found between PICP concentrations and HbA_1C and c-peptide at onset of diabetes (r =−0.45 and r = 0.47, respectively). Bone formation at onset of IDDM is not impaired; the introduction of insulin therapy, together with the achievement of a good metabolic control, determines an increase of bone matrix formation coupled with a decrease of bone resorption, that determines a positive balance of bone modeling. Received: 7 May 1996 / Accepted: 18 October 1996     

Age-related changes in bone biochemical markers and their relationship with bone mineral density in normal Chinese women

Measurements of bone biochemical markers are increasingly being used to evaluate the state of bone turnover in the management of bone metabolic diseases, especially osteoporosis. However, changes in the bone turnover rate vary with age. The aim of this study was to establish the laboratory reference range of serum bone-specific alkaline phosphatase (sBAP), serum type I collagen cross-linked C-terminal telopeptide (sCTx), and urine CTx (uCTx), based on values from 665 healthy Chinese women aged 20–80 years. We measured the levels of sBAP, sCTx, serum alkaline phosphatase (sALP), and uCTx and evaluated the age-related changes and their relationship with bone mineral density (BMD) in the anteroposterior (AP) lumbar spine, hip, and left forearm. We found significant correlations between biochemical markers and age, with coefficients of determination (R ²) of 0.358 for sBAP, 0.126 for sCTx, 0.125 for uCTx, and 0.336 for sALP. The net changes in different biochemical markers were inversely correlated with the rates of BMD loss in the AP lumbar spine. After correction for age, body weight, and height, the levels of the markers had significant negative correlations with the BMD of the AP lumbar spine, femoral neck, and ultradistal forearm. All four biochemical markers had the highest negative correlation with BMD of the AP lumbar spine (partial correlation coefficients of −0.366, −0.296, −0.290, and −0.258 for sBAP, sCTx, uCTx, and sALP, respectively). The mean and SD values of these markers in premenopausal and postmenopausal women with normal BMD values were used as the normal reference ranges. The reference ranges of sBAP, sCTx, and uCTx for pre- vs postmenopausal women were 17.3 ± 6.23 vs 18.9 ± 7.52 U/l, 3.18 ± 1.49 vs 3.23 ± 1.57 nmol/l, and 15.5 ± 11.4 vs 16.2 ± 12.4 nM bone collagen equivalents/mM urinary creatinine, respectively. Levels of the bone formation marker (sBAP) and bone resorption markers (sCTx, uCTx) increased rapidly in women with osteopenia or osteoporosis, indicating that they may be sensitive markers to determine the bone turnover rate in healthy Chinese women.     

High bone turnover of type I collagen depends on fetal growth

The bone metabolic processes of proliferation and differentiation in preterm and term newborns have yet to be fully elucidated. Seventy-four umbilical cord blood samples were collected from preterm and term newborns delivered at 27 to 42 gestational weeks (GWs). Carboxy-terminal propeptide of type I procollagen (PICP), pyridinoline cross-linked telopeptide domain of type I collagen (ICTP), alkaline phosphatase (ALP), and bone-specific alkaline phosphatase (BAP) were measured. Calcitonin (CT), estrogen (E2), intact parathyroid hormone, and insulin-like growth factor-I (IGF-I) were also examined in 20 or 23 randomly selected samples. We conducted cross-sectional regression analyses for bone metabolic markers, fetal growth markers including GWs, birth weight (BW), height (BH) and head circumference (HC), and bone related hormones. PICP and ICTP activities were very high, but decreased significantly with fetal growth based on GWs, BW, BH, and HC changes (GWs, BW, and BH to both PICP and ICTP, P < 0.0001; HC to ICTP, P < 0.0001; HC to PICP, P < 0.05), while BAP and ALP did not change significantly. E2 and CT both showed a significant positive correlation with Ca (P < 0.05), but neither hormone had any apparent correlation with PICP, ALP, BAP, or ICTP. These results suggest very active bone formation and resorption of type I collagen to be dependent on fetal growth and that fetal osteoblasts dominate the proliferation phase of development rather than the maturation phase. However, factors contributing to high bone turnover in the fetus remain to be elucidated.