Relationship of bone turnover to bone density and fractures

Soy and Bone

Interest in the use of plant estrogens (phytoestrogens) to attenuate postmenopausal bone loss has increased during the past 10 years as healthcare consumers, practitioners, and scientists have searched for alternative treatments to the use of hormone replacement therapy. Promising research has emerged regarding the potential benefit of increased consumption of phytoestrogens, primarily from dietary soy products. Dietary phytoestrogens, primarily isoflavones found in soy foods, may alter bone turnover in postmenopausal women by decreasing bone resorption and increasing bone formation.

Effects of cyclical etidronate with alfacalcidol on lumbar bone mineral density, bone resorption, and back pain in postmenopausal women with osteoporosis

The purpose of the present open-labeled, randomized, prospective study was to compare the effects of cyclical etidronate combined with alfacalcidol with those of cyclical etidronate alone on lumbar bone mineral density (BMD), bone resorption, and back pain in postmenopausal women with osteoporosis. Forty postmenopausal women with osteoporosis, 60-86 years of age, without any vertebral fractures in the lumbar spine, were randomly divided into two groups with 20 patients in each group. One group was treated with cyclical etidronate (oral etidronate 200 mg daily for 2 weeks every 3 months) and the other was given cyclical etidronate combined with alfacalcidol (cyclical etidronate plus alfacalcidol 1 Ig daily continuously). The BMD of the lumbar spine (L1-L4) measured by dual-energy X-ray absorptiometry, urinary crosslinked N-terminal telopeptides of type I collagen (NTX) measured by an enzyme-linked immunosorbent assay, and back pain evaluated by the face scale score were assessed at baseline, 6 months, and 12 months. There were no significant differences in baseline characteristics including age, body mass index, years since menopause, lumbar BMD, urinary NTX level, and face scale score between the two treatment groups. Both treatments significantly reduced the urinary NTX level and back pain. Cyclical etidronate combined with alfacalcidol significantly increased the lumbar BMD with a more significant reduction in the urinary NTX level than cyclical etidronate alone, but cyclical etidronate alone did not significantly increase the lumbar BMD. Alleviation of back pain was similar in the two groups. These results suggest that cyclical etidronate combined with alfacalcidol appears to be more useful than cyclical etidronate alone for increasing the lumbar BMD by more markedly suppressing bone resorption in postmenopausal women with osteoporosis.

Severity of prevalent vertebral fractures and the risk of subsequent vertebral and nonvertebral fractures: results from the MORE trial

Prevalent vertebral fractures and baseline bone mineral density (BMD) predict subsequent fracture risk. The objective of this analysis is to examine whether baseline vertebral fracture severity can predict new vertebral and nonvertebral fracture risk. In the randomized, double-blind 3-year Multiple Outcomes of Raloxifene Evaluation (MORE) trial, 7705 postmenopausal women with osteoporosis (low BMD or prevalent vertebral fractures) were randomly assigned to placebo, raloxifene 60 mg/day, or raloxifene 120 mg/day. Post hoc analyses studied the association between baseline fracture severity and new fracture risk in the placebo group and the effects of placebo, raloxifene 60 mg/day, and raloxifene 120 mg/day on new fracture risk in women with the most severe prevalent vertebral fractures (n = 614). Vertebral fracture severity was visually assessed using semiquantitative analysis of radiographs and categorized by estimated decreases in vertebral heights. Reported new nonvertebral fractures were radiographically confirmed. Baseline vertebral fracture severity predicted vertebral and nonvertebral fracture risk at 3 years. In women without prevalent vertebral fractures, 4.3 and 5.5% had new vertebral and nonvertebral fractures, respectively. In women with mild, moderate, and severe prevalent vertebral fractures, 10.5, 23.6, and 38.1% respectively had new vertebral fractures, whereas 7.2, 7.7, and 13.8% respectively experienced new nonvertebral fractures. Number of prevalent vertebral fractures and baseline BMD also predicted vertebral fracture risk, but the severity of prevalent vertebral fractures was the only predictor of nonvertebral fracture risk and remained a significant predictor after adjustment for baseline characteristics, including baseline BMD. In patients with severe baseline vertebral fractures, raloxifene 60 mg/day decreased the risks of new vertebral [RR 0.74 (95% Cl 0.54, 0.99); P = 0.048] and nonvertebral (clavicle, humerus, wrist, pelvis, hip, and leg) fractures [RH 0.53 (95% CI 0.29, 0.99); P = 0.046] at 3 years. To prevent one new fracture at 3 years in women with severe baseline vertebral fractures with raloxifene 60 mg/day, the number needed to treat (NNT) was 10 for vertebral and 18 for nonvertebral fractures. Similar results were observed in women receiving raloxifene 120 mg/day. In summary, baseline vertebral fracture severity was the best independent predictor for new vertebral and nonvertebral fracture risk. Raloxifene decreased new vertebral and nonvertebral fracture risk in the subgroup of women with severe vertebral fractures at baseline. These fractures may reflect architectural deterioration, independent of BMD, leading to increased skeletal fragility.

Is the paradigm shifting?

Reduction in bone mass has long dominated the thinking about and approach to the problem of osteoporosis. A now large body of evidence indicates that bone mass is not adequate to explain satisfactorily either the skeletal fragility of osteoporosis or the effects of bone active agents. By contrast, bone remodeling activity seems to provide a better explanation of both. It is suggested that current syntheses in the field are shifting to this conclusion. In attempting to make sense out of how a process designed by evolution to sustain bone strength could instead be contributing to weakness, I suggest: (1) prevailing bone remodeling levels are substantially higher than are optimal for maintenance of bone strength; (2) this high level has discernible environmental causes; and (3) such high remodeling is a major source-perhaps the major source-of osteoporotic bony fragility. Within this context, reduced bone mass, rather than the primary cause of fracture, is seen as a factor that predisposes individuals to the harmful effects of excessive remodeling.

Relationship between dental panoramic radiographic findings and biochemical markers of bone turnover

We investigated whether mandibular cortical measures on dental panoramic radiographs are associated with biochemical markers of bone turnover in 82 postmenopausal women. Mandibular cortical shape was significantly associated with biochemical markers and spinal BMD. Our results suggest that dentists may be able to identify postmenopausal women with low BMD by using dental panoramic radiographs.

INTRODUCTION

Recent studies suggest that mandibular inferior cortical shape and width on dental panoramic radiographs may be useful screening tools for low skeletal bone mineral density (BMD) or increased risk of osteoporotic fracture. However, little is known as to whether these measures are associated with bone turnover. We investigated relationships among dental panoramic radiographic findings, spine BMD, and biochemical markers of bone turnover in postmenopausal women.

MATERIALS AND METHODS

Of 609 women who visited our clinic for BMD assessment between 1996 and 2002, 82 Japanese postmenopausal women, 46-68 years of age (54.1 +/- 4.9 years), were recruited for this study. Mandibular inferior cortical shape (normal, mild/moderate erosion, severe erosion) and width were evaluated on dental panoramic radiographs. BMD at the lumbar spine (L2-L4) was measured by DXA and categorized as normal (T-score > -1.0), osteopenia (T-score, -1.0 to -2.5), or osteoporosis (T-score < -2.5). Bone turnover was estimated by serum total alkaline phosphatase (ALP) and urinary N-telopeptide cross-links of type I collagen (NTx), corrected for creatinine.

RESULTS

The odds of low spine BMD in subjects with any cortical erosion were 3.8 (95% CI, 1.2-12.5). Mandibular cortical erosion was significantly associated with increased NTx (p < 0.001) and ALP (p < 0.05) levels. The associations of spine BMD with NTx and ALP were similar. Mandibular cortical width was significantly associated with spine BMD but not with NTx and ALP levels.

CONCLUSIONS

Our results suggest that mandibular inferior cortical shape on dental panoramic radiographs may be an indicator of bone turnover and spine BMD in postmenopausal women. Dentists may be able to identify postmenopausal women with increased risk of osteopenia and osteoporosis on routine dental panoramic radiographs.

Longitudinal changes in bone density in relation to oral contraceptive use

The primary aim of this 36-month prospective cohort study was to evaluate the association between use of oral contraceptives (OCs) and bone mineral density in reproductive-age women. The 36-month bone density (g/cm2) at the spine, hip and whole body and percent change from baseline (measured at 6-month intervals) were evaluated among 245 women 18-39 years of age; 89 were using OCs (median duration: 3.7 years at study entry) and 156 were not using any hormonal contraception. Before and after adjustment for covariates (baseline bone density, age, race, ever pregnant, exercise, body mass and calcium intake), women using OCs did not differ significantly from comparison women in percent change in bone density over 36 months or in absolute bone density at 36 months. All p-values for between-group differences were >0.55. In conclusion, within the limitations of this study, OCs did not appear to impact bone density over time in this cohort of reproductive-age women.

Preventive effects of sequential treatment with alendronate and 1 alpha-hydroxyvitamin D3 on bone mass and strength in ovariectomized rats

Because accumulating evidence has shown that bisphosphonates are unable to maintain their bone-sparing effects after the withdrawal of the drug, a replacement treatment is needed when bisphosphonate treatment cannot be continued for some reason. The present study investigated the preventive effects of alendronate followed by 1alpha(OH)D3 on the mass and mechanical strength of trabecular and cortical bones in ovariectomized rats. Sprague-Dawley rats were ovariectomized or sham-operated at 48 weeks of age. Ovariectomized rats treated with vehicle alone (OVX group) showed significant decreases in bone mineral density (BMD) and mechanical strength of the lumbar vertebra and the midfemur during a 20-week period after the operation as compared with sham-operated rats. These decreases were prevented by continuous treatment with alendronate (0.5 mg/kg/day, po) for 20 weeks (ALN-C group), whereas the values reverted to those of the OVX group when alendronate was withdrawn at 10 weeks (ALN-W group). The sequential treatment with alendronate and 1alpha(OH)D3 (0.05 microg/kg/day, po) for 10 weeks each (ALN --> 1alpha group) resulted in higher BMD and mechanical strength of the lumbar vertebra and the midfemur in this group than in the OVX and ALN-W groups. The increase in mechanical strength was proportional to that in BMD at both sites, suggesting that the stimulatory effects of these treatments on bone strength were due to those on bone mass. Analyses of histology, computed tomography, and biochemical markers confirmed the preventive effects of the sequential treatment. Therefore, we propose that 1alpha(OH)D3 may be a good choice to replace alendronate when alendronate treatment cannot be continued for some reason.

The effect of age, weight, and lifestyle factors on calcaneal quantitative ultrasound: the ESOPO study

Quantitative ultrasound (QUS) techniques have been shown to be as good as bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry (DXA), in predicting fracture risk: QUS technique could increase substantially the accessibility to a reliable bone osteoporosis risk evaluation, but little is know regarding the relationship of QUS to risk factors that have been found to predict DXA-BMD values and this is even more true in men. We studied 6,811 postmenopausal women 40 to 80 years of age and 4,981 men 60-80 years of age representative of the general population of all regions of Italy. All participants were questioned on lifestyle habits and on their medical history. After a physical examination "bone stiffness" (called here for simplicity, stiffness), which is derived from the values of broadband ultrasound attenuation (BUA) and speed of sounds (SoS) was measured by a heel QUS device (Achilles apparatus, Lunar, Madison, USA). The most common recognized determinants of bone mass (either categorical or continuous variables) were modeled with stiffness by multiple regression analysis or ANOVA. Stiffness was strongly related to age and weight. After adjusting for these variables, the women who had taken hormone replacement therapy for more than a year had significantly higher stiffness values. The difference versus nonusers remained significant for up to 20 years-since-menopause (YSM). This effect was so strong that for further analysis these women were excluded. By multivariate analysis, stiffness was then found to be significantly related to recalled body weight at 25 years of age, actual and past cigarettes smoked per day, and dairy calcium intake. Stiffness was also associated with a number of categorial factors adjusted for age, weight, and YSM: prior ovariectomy, history of more than 2 months confined to bed, outdoor physical activity, smoking, chronic use of any drug, and past corticosteroid use. All these categorial and continuous variables predicted stiffness equally in men and women. In conclusion, QUS bone measurements discriminate postmenopausal women according to past use of hormone replacement therapy. Risk factors usually associated to BMD as measured by DXA are also associated to calcaneal bone stiffness as measured by QUS, and most risk factors for osteoporosis usually observed in women are equally applicable to men.

Interest of biochemical markers of bone turnover for long-term prediction of new vertebral fracture in postmenopausal osteoporotic women

OBJECTIVE

To analyse the interest of baseline levels and short-term (3-months) changes in serum osteocalcin (BGP), serum bone-specific alkaline phosphatase (BALP) and urinary C-telopeptide of type I collagen/creatinine ratio (U-CTX) to predict 3-years changes in bone mineral density (BMD) and spinal deformity index (SDI) in postmenopausal osteoporotic women.

METHODS

Data were derived from a cohort of 603 osteoporotic women corresponding to the placebo arm of a 3-years prospective, double-blind study.

RESULTS

Baseline values of BALP, BGP and U-CTX were negatively and significantly correlated with baseline spinal BMD. Significant correlations were also observed between the changes in BMD observed after 36 months at the spine and baseline BALP (r=0.20, P=0.0001), BGP (r=0.09, P=0.05) and U-CTX (r=-0.11, P=0.02). At 3 years, 71 women (15.9%) showed an increase in their SDI, corresponding to the occurrence of at least one new vertebral deformity. Baseline values of the four bone turnover markers (BTM) were not significantly related to the occurrence of new vertebral deformities. However, when considering the changes in the BTM observed after 3-months of follow-up, BGP (P=0.003) and U-CTX (P=0.047) were identified as significant predictors of an increase of SDI. The associated odds ratios (95% confidence interval (CI)) were 10.922 (2.218-53.78) for unit changes of log BGP and 1.369 (1.003-1.867) for unit changes of logU-CTX. The relative risk (RR) (IC 95%) of having a new vertebral fracture over 36 months was 0.31 (0.15-0.65) when being in the lowest quartile of 3-months changes in BGP as compared with the highest.

CONCLUSION

We conclude that two sequential measurements of BGP and U-CTX performed at 3-months intervals could be of interest to identify postmenopausal osteoporotic women with the highest risk to present new vertebral deformities.

Insufficiency fracture of the femoral neck during osteoporosis treatment: a case report

Acase of insufficiency fracture of the femoral neck that occurred during treatment for osteoporosis is reported. A 77-year-old woman (height 150 cm, body weight 43 kg) with osteoporosis associated with high bone turnover was treated with oral cyclical etidronate (400 mg/day for 2 weeks every 3 months). Three months after the treatment was started the patient experienced pain in the right hip joint while walking despite no evidence of trauma. Although radiographs were normal, weight-bearing was not possible because of pain. T2-weighted magnetic resonance (MR) imaging was used to detect a fracture line localized on the inferior aspect of the femoral neck. Because on bone marker measurement bone resorption was increased and bone formation was decreased from baseline, treatment was switched to oral alendronate (5 mg/day, daily). Pain resolved 3 weeks after the fracture was evident, and free gait was possible during the following 3 weeks. Follow-up radiographs, obtained 3 and 6 months after the fracture was evident, showed bony sclerosis on the aspect in which the fracture line was observed on the T2-weighted MR image. The dissociation (imbalance) of bone formation and resorption was also alleviated. A possibility of increased bone fragility should be kept in mind when oral cyclical etidronate is applied to elderly Japanese, small-physique women with osteoporosis at a daily dose of 400 mg (higher dose).

Effects of 5-year treatment with elcatonin and alfacalcidol on lumbar bone mineral density and the incidence of vertebral fractures in postmenopausal women with osteoporosis: a retrospective study

The purpose of this retrospective study was to compare the effects of long-term treatment (5 years) with elcatonin and alfacalcidol on bone mineral density (BMD) and the incidence of vertebral fractures in postmenopausal women with osteoporosis. Fifty-six osteoporotic women, more than 5 years after menopause and 58-79 years of age, were enrolled in the study and allocated to an elcatonin treatment group (20 units IM, weekly; n = 30) or an alfacalcidol treatment group (1 micro g/day, daily; n = 26). BMD of the lumbar spine (L2-L4) was measured by dual energy X-ray absorptiometry at baseline and every year for 5 years. There were no significant differences in age, body mass index, years since menopause, BMD, or number of prevalent vertebral fractures at baseline between the two groups. One-way analysis of variance with repeated measurements showed no significant longitudinal changes in BMD in either group, suggesting that both treatments sustained the BMD over 5 years. Two-way analysis of variance with repeated measurements also showed no significant differences in longitudinal changes in BMD between the two groups, suggesting that the effects of the two treatments on BMD were similar. However, the number of incident vertebral fractures per patient was significantly lower in the alfacalcidol treatment group than in the elcatonin treatment group (0.80 +/- 1.19 and 2.08 +/- 2.73, respectively; P < 0.05). These findings indicate that both treatments appeared to sustain lumbar BMD similarly over a 5-year period in postmenopausal women with osteoporosis, but alfacalcidol treatment may be superior to elcatonin treatment regarding the incidence of vertebral fractures. Further study with prospective observations are needed to confirm the results of the present study.

A theoretical analysis of the changes in basic multicellular unit activity at menopause

Bone loss at menopause is an important contributor to the development of osteoporosis in women. Although alterations in bone remodeling are the implied process through which bone is lost at menopause, how menopause influences basic multicellular units (BMUs), the teams of cells that perform bone remodeling, is not completely clear. In this analysis we utilize a computer simulation of BMU activity to evaluate the changes that occur at menopause. Transient and maintained changes in both the rate of bone turnover (expressed as the BMU birthrate or origination frequency) and the focal bone balance (differences between the amount of bone formed and resorbed at each remodeling site) are considered. The magnitude of the change in BMU activity is determined parametrically through comparison to lumbar spine bone mineral density data present in the literature. We find that a change in bone turnover that is maintained after menopause, a transient change in focal bone balance at menopause, or a combination of the two is consistent with bone loss patterns seen clinically. Understanding the changes in BMU activity that occur at menopause could lead to improved strategies to treat and prevent postmenopausal osteoporosis.

Biochemical markers of bone remodeling

Because of the aging population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to everyday clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis, and follow-up of such pathologies has markedly grown. Together with clinical and imaging techniques, laboratory tests play an important role in the assessment and differential diagnosis of metabolic bone disease.

Comparison of biochemical markers of bone turnover and bone mineral density between hip fracture and vertebral fracture

Bone density and the biochemical markers of bone turnover were compared between 26 hip-fracture patients and 41 vertebral-fracture patients after age adjustment to investigate whether or not type of osteoporosis differs between hip fracture and vertebral fracture. C-Terminal propepides of type I collagen (PIPC) was lower in hip fracture than vertebral fracture. The other bone formation markers (bone-specific alkaline phosphatase [ALP], osteocalcin) tended to be lower, and bone resorption markers (deoxypyridinoline, C-telopeptide crosslinking of type I collagen [CTX] tended to be higher in hip fracture compared to vertebral fracture. Mean of Z-scores of spine bone mineral density (BMD) in hip fracture and vertebral fracture were -0.461 and -0.919, respectively. Mean of Z-scores of femoral neck BMD in hip fracture and vertebral fracture were -0.994 and -0.361, respectively. All Z-scores were negative values, which means reduction of BMD compared to decade-matched controls. Z-scores of bone formation markers, such as bone-specific ALP, osteocalcin, and PIPC, were positive values in vertebral fracture, which means an increase against decade-matched controls, whereas those were negative values in hip fracture. Z-scores of bone resorption markers, such as deoxypyridinoline and CTX, were greater in hip fracture than in vertebral fracture. To express bone balance between formation and resorption in hip fracture and vertebral fracture, we calculated an uncoupling status index (USI) by the values of biochemical markers. USI of hip fracture showed a great negative value (-1.29), which indicates excess of bone resorption over formation, whereas that of vertebral fracture showed a small positive value (0.23). In conclusion, bone formation markers increase in vertebral fractures, but decrease in hip fracture. Bone resorption markers increase in both fracture, but greater increase in hip fracture.

Effects of long-term risedronate on bone quality and bone turnover in women with postmenopausal osteoporosis

The effects of 3 years of oral risedronate treatment on bone quality and remodeling were assessed in women with postmenopausal osteoporosis. Transiliac bone biopsies were obtained at baseline and after treatment with placebo or risedronate 5 mg/day in 55 women (placebo, n = 27; risedronate 5 mg, n = 28); these pairs of samples allowed comparison of treatment effects vs. both baseline values and between treatment groups. A further 15 women (placebo, n = 6; risedronate 5 mg, n = 9) had measurements from a posttreatment biopsy, but not from a baseline biopsy. Samples were examined for qualitative changes (e.g., osteomalacia, peritrabecular fibrosis, and woven bone); no histological abnormalities were found to be associated with treatment. Among women with both baseline and posttreatment biopsies, risedronate-treated women experienced a moderate and expected reduction from baseline in bone turnover, which was reflected in mean decreases in mineralizing surface of 58% and in activation frequency of 47%. Histomorphometrical parameters indicated that bone formation rate decreased significantly from baseline with risedronate treatment, reflecting a decrease in bone turnover; bone mineralization was normal following treatment. Basic multicellular unit (BMU) balance tended to improve in the risedronate-treated women, whereas it tended to worsen in the placebo-treated women, although these changes were not statistically significant. There were no significant changes in structural parameters with treatment. The effects of 3 years of risedronate treatment on bone histology and histomorphometry reflect the antiresorptive mechanism of action, and are consistent with the antifracture efficacy and favorable bone safety profile demonstrated in large clinical trials.

Injectable hormone contraception and bone density: results from a prospective study

BACKGROUND

Depot medroxyprogesterone acetate (DMPA) injectable contraception may decrease bone density and increase the risk for osteoporosis in later life. Prospective data are scarce, especially of the effects of DMPA discontinuation on bone.

METHODS

Between 1994 and 1999, we conducted a population-based prospective cohort study among women enrollees of a Washington State health maintenance organization. We enrolled 457 nonpregnant women, ages 18-39 years (183 DMPA users and 274 non-users). Bone density was measured by dual-energy x-ray absorptiometry every 6 months for 3 years.

RESULTS

Bone density decreased notably among DMPA-exposed women at the spine (adjusted mean bone density was -0.0053 gm/cm for DMPA users compared with +0.0023 gm/cm for non-users for each 6-month interval) and total hip (-0.0060 compared with -0.0002 gm/cm ). This represents an annualized mean rate of change at the spine of -0.87% compared with +0.40% and, at the hip, -1.12% compared with -0.05%. Discontinuers of this method (N = 110) showed sizable increases in bone density over comparison women (for each 6-month interval, adjusted mean spine bone density was +0.0067 gm/cm compared with +0.0023 gm/cm, respectively; adjusted mean hip bone density was +0.0035 compared with -0.0002 gm/cm ). Estimated annualized mean rates of change were +1.41% compared with +0.40% [corrected] at the spine and +1.03% [corrected] compared with -0.05% at the hip. After 30 months, mean bone density for discontinuers was similar to that of non-users.

CONCLUSIONS

In this study, DMPA use was strongly associated with bone density loss. Substantial postdiscontinuation recovery of bone provides evidence that the effects may be largely reversible.

Short-term vitamin A supplementation does not affect bone turnover in men

Limited data in humans and animals indicate that excess vitamin A stimulates bone resorption and inhibits bone formation, effects that over time might lead to bone loss and fracture. Thus, it is possible that vitamin A supplementation is a currently unrecognized risk factor for the development of osteoporosis. To further evaluate this possibility, a prospective, randomized, single-blind study of vitamin A supplementation was conducted in 80 healthy men age 18-58 y. One half received 7576 microg (25,000 IU) of retinol palmitate daily with their evening meal; the others took a placebo. Blood was collected from fasting subjects and serum prepared at baseline and after 2, 4 and 6 wk of supplementation. Serum bone specific alkaline phosphatase (BSAP) and N-Telopeptide of type 1 collagen (NTx) were measured at all time points. Serum osteocalcin (Oc) was measured at baseline and after 6 wk of supplementation. BSAP, NTx and Oc did not differ between the supplemented and placebo-treated groups over the course of the study. In conclusion, short-term vitamin A supplementation at this dosage in healthy men does not alter serum markers of skeletal turnover. Thus, it is unlikely that short-term administration of vitamin A would contribute to the development of osteoporosis. Whether long-term vitamin A supplementation might have adverse skeletal effects remains to be determined.

Screening for osteoporosis in patients with inflammatory bowel disease by using urinary N-telopeptides

BACKGROUND

Patients with inflammatory bowel disease are at increased risk of osteoporosis.

DESIGN AND METHODS

We carried out a prospective study of bone mineral density and biochemical markers of bone metabolism like osteocalcin and urinary N-telopeptides in 72 patients with inflammatory bowel disease and evaluated if one of these markers detects osteoporosis. In addition, bone mineral density and N-telopeptides were analysed retrospectively in a second series of 93 patients with inflammatory bowel disease in order to assess predictive values found in the first patient group in an independent sample.

RESULTS

Multiple linear regression showed that N-telopeptides (P < 0.0001) and total white blood cell count (P = 0.006) correlated negatively with the bone mineral density of the lumbar spine and only N-telopeptides (P = 0.005) correlated negatively with the bone mineral density of the femoral neck. Using receiver operator characteristic curves N-telopeptide concentrations of > 40 (30) nmol N-telopeptides/mmol creatinine were chosen as best cut-off values to exclude osteoporosis at the lumbar spine (femoral neck). Using these cut-off values a negative predictive value of 100% (100%) and a positive predictive value of 37.5% (27.9%) were found in the first group, and a negative predictive value of 95.2% (96%) and a positive predictive value of 15.6% (23.3%) in the second, independent group of patients.

CONCLUSION

Our data suggest that N-telopeptide levels could be used as a tool for the screening of osteoporosis and for selecting those inflammatory bowel disease patients where bone mineral density measurement is indicated.

The efficacy of two dosages of a continuous combined hormone replacement regimen

OBJECTIVES

To evaluate the efficacy of a low-dose combination of estradiol (E2) and norethisterone acetate (NETA) on bone markers, lipid and bleeding profiles and menopausal symptoms.

METHOD

Ninety-six healthy Chinese postmenopausal women were allocated randomly to receive 1 mg E2/0.5 mg NETA (low-dose hormone replacement therapy (HRT)) or 2 mg E2/1 mg NETA (high-dose HRT) for 6 months.

RESULTS

Bone resorption markers (collagen I N-terminal telopeptides (NTX) and deoxypyridinoline (dPyr)) were significantly reduced; -66 and -32%, respectively, in high-dose HRT versus -55 and -24%, respectively, in low-dose HRT. Bone-specific alkaline phosphatase remained unchanged with either combination of hormones. Total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels were decreased significantly (-12 and -13%, respectively, in high-dose HRT vs. -7 and -8% in low-dose HRT). High density lipoprotein cholesterol (HDL-C) was decreased to a lesser extent in low-dose HRT and triglycerides (TG) levels remained unchanged. Both the low and high-dose HRT were effective in alleviating menopausal symptoms. After 6 months of treatment, 2% of women in the low-dose HRT were bleeding compared with 23% in the high-dose HRT. Breast pain occurred in 2% of women in low-dose HRT compared with 15% in high-dose HRT. The endometrium in the majority of the women remained normal.

CONCLUSION

Menopausal symptoms were reduced effectively in postmenopausal women on either low-dose or high-dose HRT. TC, LDL-C levels and bone resorption markers were reduced in a dose-dependent manner. Low-dose HRT provided a better bleeding profile and the incidence of breast pain was low.

Age- and gender-related differences in bone mineral status and biochemical markers of bone metabolism in Northern Chinese men and women

The aim of this study was to provide insight into the bone mineral status and biochemical markers of bone metabolism in a Chinese population from Shenyang, in the north of China, where hip fracture incidence is low. A total of 194 healthy men and women, aged 25-35 years and 65-75 years, were studied. Bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) was measured using dual-energy X-ray absorptiometry. Fasting blood and 24 h urine samples were collected for bone alkaline phosphatase (bAP), osteocalcin, calcium, phosphate, and free deoxypyridinoline (Dpd). Both older women and men had lower BMD compared with younger women and men by 27.2 +/- 3.0% (mean +/- SE) and 9.8 +/- 3.0% at the LS and 22.0 +/- 3.4% and 12.8 +/- 3.4% at the FN, respectively, after adjusting for bone and body size (p < 0.01). BMD at the two sites was lower in older women than in older men by 10.7 +/- 4.1% and 10.2 +/- 4.2%, respectively, after size correction (p < 0.05). Plasma bAP, osteocalcin, calcium, and phosphate concentrations were higher in older women than younger women by 69.3 +/- 9.7%, 77.2 +/- 11.1%, 7.5 +/- 2.3%, and 8.0 +/- 3.8%, respectively, and older men by 67.6 +/- 11.1%, 72.1 +/- 11.0%, 7.7 +/- 2.3%, and 23.8 +/- 3.8%, respectively (p < 0.01). However, plasma osteocalcin, calcium, and phosphate concentrations were lower in older men compared with their younger counterparts by 35.6 +/- 11.0%, 8.7 +/- 2.3%, and 14.1 +/- 3.8%, respectively (p < 0.05). Urinary calcium and phosphate output were lower in older men compared with younger men by 48.0 plus minus 10.3% and 27.6 +/- 6.9%, respectively (p < 0.01), whereas there were no differences between older and younger women. No differences in Dpd between older and younger groups were found. This study demonstrates that bone mineral status is lower in older people in Shenyang, as has been shown in populations elsewhere. The pronounced low bone mineral status in older women may be associated with increased bone turnover, which was not observed in older men.

Assessment and Recommendations on Factors Contributing to Preanalytical Variability of Urinary Pyridinoline and Deoxypyridinoline

Background: Pyridinoline (PYD) and deoxypyridinoline (DPD) are two of the most extensively characterized biochemical bone markers, but the interpretation of results is hampered by biologic and other preanalytical variability. We reviewed factors contributing to preanalytical variation of pyridinium cross-links in urine.

Methods: We searched four databases for English-language reports on PYD and/or DPD in urine. Searches were restricted to humans, except for studies of stability, when the search was expanded to other species. The 599 identified articles were supplemented with references from those articles and with articles known to the authors.

Results: The mean reported within-day variability was 71% for PYD (range, 57–78%) and 67% for DPD (range, 53–75%). The mean interday variability was 16% for both DPD and PYD (range for PYD, 12–21%; range for DPD, 5–24%). The mean intersubject variabilities across studies were 26% for PYD (range, 12–63%) and 34% for DPD (range, 8–98%) for healthy premenopausal women and 36% (range, 22–61%) and 40%, (range, 27–54%) for postmenopausal women, respectively. Specimen instability and errors in creatinine measurements were additional sources of variability.

Conclusions: Intra- and intersubject variability can be reduced by collecting specimens at a specific time of the day and by maintaining similar patient status at each specimen collection regarding factors such as medications and dietary supplements.

Relationships between bone mineral density and incident vertebral fracture risk with raloxifene therapy

Although low absolute values of bone mineral density (BMD) predict increased fracture risk in osteoporosis, it is not certain how well increases in BMD with antiresorptive therapy predict observed reductions in fracture risk. This work examines the relationships between changes in BMD after 1 year or 3 years of raloxifene or placebo therapy and the risk for new vertebral fractures at 3 years. In the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, 7705 postmenopausal women with osteoporosis were randomized to placebo or raloxifene 60 mg/day or 120 mg/day. Relationships between baseline BMD and changes in BMD from baseline with the risk of new vertebral fractures were analyzed in this cohort using logistic regression models with the raloxifene doses pooled. As has been observed in other populations, women with the lowest baseline lumbar spine or femoral neck BMD in the MORE cohort had the greatest risk for vertebral fractures. Furthermore, for any percentage change, either increase or decrease in femoral neck or lumbar spine BMD at 1 year or 3 years, raloxifene-treated patients had a statistically significantly lower vertebral fracture risk compared with placebo-treated patients. The decrease in fracture risk with raloxifene was similar across the range of percentage change in femoral neck BMD observed at 3 years; patients receiving raloxifene had a 36% lower risk of vertebral fracture compared with those receiving placebo. At any percentage change in femoral neck and lumbar spine BMD observed at 1 year, raloxifene treatment decreased the risks of new vertebral fractures at 3 years by 38% and 41%, respectively. The logistic regression model showed that the percentage changes in BMD with raloxifene treatment accounted for 4% of the observed vertebral fracture risk reduction, and the other 96% of the risk reduction remains unexplained. The present data show that the measured BMD changes observed with raloxifene therapy are poor predictors of vertebral fracture risk reduction with raloxifene therapy.

Mechanism of circadian variation in bone resorption

The diurnal variation in bone resorption markers is poorly understood and may contain essential information about regulation of bone resorption. To explore the acute regulation of bone resorption we studied bone turnover in 14 postmenopausal women during a randomized, crossover, 24 h study of oral glucose tolerance test (OGTT), normal diet, or fasting. Whereas fasting counteracted variation in bone resorption, as measured by serum C-telopeptide fragments of collagen type 1 degradation (s-CTx), OGTT and normal diet induced a 50% reduction (p < 0.001) over 2 h. For OGTT, s-CTx reverted to baseline levels after 6 h, and for normal diet s-CTx remained suppressed during the afternoon and returned to baseline overnight. Repeated OGTT at 8:00 A.M. and 8:00 P.M. in nine postmenopausal women demonstrated that identical reductions in s-CTx could be obtained at both timepoints with an intermediate return to baseline between tests. A 2 h randomized, crossover study of OGTT and fasting in 23 men and premenopausal women similarly revealed a 50% decrease in s-CTx. A randomized, crossover 2 h study of insulin tolerance test compared with fasting in six men and premenopausal women demonstrated a 20%-30% decrease in s-CTx (p < 0.01-0.05). Nine hour follow-up of ten healthy individuals during a crossover experiment of OGTT, protein, and fat intake revealed a comparable 50% reduction in s-CTx, but distinct profiles of serum glucose and serum insulin. Bone resorption was reduced by intake of food, glucose, fat, and protein and counteracted by fasting, and this seems to have been be independent of age and gender. Both exogenous and endogenous insulin stimulation tests induced a reduction in bone resorption, but this was only partial when compared with the reduction observed during food intake.

Reconsidering the effects of antiresorptive therapies in reducing osteoporotic fracture

Concepts of what constitutes osteoporosis have evolved from the single criterion of low bone mass to a more inclusive consideration of bone strength, based on both quantity and quality. The evidence driving this shift is drawn from many sources. For example, recent studies of bone geometry have shown what engineers have always known: material properties and structural strength are inseparable. Genetic factors also argue against a one-dimensional (ID) view of osteoporosis. Large-scale family studies present a strong case for genetic influences on bone mass and predisposition to fracture. The contribution of aging to fracture risk has long been known, but we are only now beginning to understand what happens to bone remodeling and microstructure in an aging skeleton. The recognition that osteoporosis is far more complex than previously thought suggests that factors in addition to bone mineral density (BMD) may be useful for evaluating bone fragility and therapeutic effectiveness. Although assessment of BMD is noninvasive and widely available, the degree of increase in BMD alone fails to account for the broader effectiveness of antiresorptive agents in reducing the risk of fractures related to osteoporosis. Indeed, the very multiplicity of factors that determine fracture risk implies that response to therapy may be equally complex. Studies of response to antiresorptive agents and the cellular processes they induce are at best preliminary at this time. Although new technologies have been applied to studying bone microarchitecture, their invasive nature limits wide use. New methods are needed to provide insight into the causes and effects of bone fragility. The definition of osteoporosis, meanwhile, must still be considered a work in progress.

Effects of a hydrogenated form of vitamin K on bone formation and resorption

BACKGROUND

Hydrogenation of vegetable oils affects blood lipid and lipoprotein concentrations. However, little is known about the effects of hydrogenation on other components, such as vitamin K. Low phylloquinone (vitamin K1) intake is a potential risk factor for bone fracture, although the mechanisms of this are unknown.

OBJECTIVE

The objective was to compare the biological effects of phylloquinone and its hydrogenated form, dihydrophylloquinone, on vitamin K status and markers of bone formation and resorption.

DESIGN

In a randomized crossover study in a metabolic unit, 15 young adults were fed a phylloquinone-restricted diet (10 microg/d) for 15 d followed by 10 d of repletion (200 microg/d) with either phylloquinone or dihydrophylloquinone.

RESULTS

There was an increase and subsequent decrease in measures of bone formation (P = 0.002) and resorption (P = 0.08) after dietary phylloquinone restriction and repletion, respectively. In comparison with phylloquinone, dihydrophylloquinone was less absorbed and had no measurable biological effect on measures of bone formation and resorption.

CONCLUSION

Hydrogenation of plant oils appears to decrease the absorption and biological effect of vitamin K in bone.

Bone metabolism in children with human immunodeficiency virus infection receiving highly active anti-retroviral therapy including a protease inhibitor

We measured serum osteocalcin levels in prepubertal children with human immunodeficiency virus (HIV) infection receiving highly active antiretroviral therapy including a protease inhibitor and uninfected control children. Osteocalcin values were significantly elevated in the HIV-infected patients. Though osteocalcin serves as an index of bone formation, it likely functions as a negative regulator of bone formation. Further study is necessary to determine whether protease inhibitors normalize bone physiology or decrease bone formation and reduce bone mineral density in children receiving these therapies.

Bone mineral density and bone loss measured at the radius to predict the risk of nonspinal osteoporotic fracture

Low bone mineral density (BMD) and, probably, the rate of bone loss (RBL) are associated with the risk of osteoporotic fractures. To estimate the risk of nonspinal fracture in osteoporotic women, we measured BMD and RBL in a prospective study (average follow-up, 5.38 years) in 656 postmenopausal women. The women were considered in three groups: group A (whole population), group B (women under the age of 65 years) and group C (women over the age of 65 years). At the beginning of the study, BMD was measured at the distal radius (DR) and at the proximal radius (PR) using a single-energy densitometer. BMD measurements made 2 years previously in the same patients were used to calculate RBL. Then patients were checked annually for nonspine fracture due to minor trauma. During follow-up, 121 nonspinal fractures were detected. Women with fractures were older and had lower BMD. With the Cox regression, age-corrected BMD at both DR and PR predicts fracture risk in groups A and B but not in group C. After correction for potential confounders, DR still predicts fractures in groups A and B whereas PR predicts fractures only in group B. In group C, only the RBL at the PR was predictive of the fracture risk as well as in the other two groups. Specific types of fractures are predictable in the whole population at the wrist. In conclusion, radial BMD predicts the risk of nonspine fractures except in women over the age of 65 years. The RBL at the PR is an effective predictor of fracture risk also in women over the age of 65 years.

Abnormal bone turnover in long-standing Crohn's disease in remission

BACKGROUND

A high prevalence of osteoporosis is found in patients with Crohn's disease. The pathogenesis of this condition seems to be multifactorial and its pathophysiology is still not completely understood.

AIM

To elucidate the pathophysiology of osteopenia in quiescent Crohn's disease.

METHODS

Bone turnover was studied in 26 patients (13 males and 13 females) with long-standing quiescent Crohn's disease and small bowel involvement. Bone mineral density was assessed by dual energy X-ray absorptiometry. Biochemical markers for bone formation (osteocalcin and bone-specific alkaline phosphatase) and for bone resorption (deoxypyridinoline and collagen type I C-terminal crosslinks) were measured. Urinary calcium excretion was determined.

RESULTS

Markers for bone formation were significantly lower in patients than in controls (osteocalcin: P= 0.027, bone-specific alkaline phosphatase: P < 0.001), but both bone resorption markers were not significantly different. Urine calcium excretion was significantly decreased in patients (P=0.002) compared to controls. Bone mineral density of the lumbar spine was significantly and inversely correlated with bone-specific alkaline phosphatase and collagen type I C-terminal crosslinks.

CONCLUSIONS

Bone turnover in long-standing Crohn's disease in clinical remission is characterized by suppressed bone formation and normal bone resorption. Urine calcium excretion is decreased. Hence, interventions and therapy should be directed towards the improvement of bone formation.

Inhaled corticosteroids reduce bone mineral density in early postmenopausal but not premenopausal asthmatic women

Inhaled corticosteroids are widely used in the treatment of bronchial asthma, but it is still uncertain whether long-term use of the inhaled corticosteroids affects bone metabolism in asthmatic patients. In this study, we examined the effect of inhaled beclomethasone dipropionate (BDP) on bone mineral density (BMD) and biochemical markers of bone metabolism in pre- and early postmenopausal asthmatic women. Thirty-six (17 premenopausal and 19 early postmenopausal) asthmatic women and 45 healthy control (24 premenopausal and 21 early postmenopausal) women were investigated. All the asthmatic patients were treated with BDP (542 +/- 298 microg/day; 100-1200 microg/day) without any systemic administration of corticosteroids for at least 1 year. In premenopausal women, BMD as well as the biochemical markers of bone metabolism did not differ between control subjects and BDP-treated asthmatic patients. By contrast, in early postmenopausal women, BMD was significantly lower in BDP-treated asthmatic patients than in control subjects. In these early postmenopausal women, serum intact osteocalcin concentration was lower in the BDP-treated asthmatic patients than in the control subjects whereas urinary free pyridinoline (F-PYD) and free deoxypyridinoline (F-DPD) concentrations did not differ between the groups. Thus, early postmenopausal, but not premenopausal, asthmatic patients who were treated with inhaled BDP had reduced BMD, which was associated with a decreased level of the bone formation marker. Ovarian hormones may be protective against the adverse effect of inhaled BDP on bone metabolism in the premenopausal patients.

Evaluation of a Fully Automated Serum Assay for C-Terminal Cross-Linking Telopeptide of Type I Collagen in Osteoporosis

Background: Biochemical markers of bone turnover can provide prognostic information about the risk of osteoporotic fracture and are useful tools for monitoring efficacy of antiresorptive therapy. A serum-based automated assay may be of better clinical value than urinary markers because of lower imprecision and day-to-day within-person variability. Our aim was to evaluate the technical and clinical performances of a new, fully automated assay for serum C-terminal cross-linking telopeptide of type I collagen (CTX), a marker of bone resorption.

Methods: Serum CTX was measured on the Elecsys 2010 automated analyzer (Roche). Results were compared with those of the manual ELISA. We measured serum CTX concentrations in 728 healthy women, ages 31–89 years. We investigated the ability of this assay to predict the rate of postmenopausal forearm bone loss evaluated by four repeated bone mineral density measurements using dual-x-ray absorptiometry in 305 women followed prospectively for 4 years. Finally, in a cohort of healthy, untreated, postmenopausal women, we compared baseline serum CTX in 55 women who subsequently had a fracture (20 vertebral and 35 peripheral fractures) with values in the 380 women who did not fracture during a mean 5 years of follow-up.

Results: The within- (n = 21) and between-run (n = 21) CVs were &lt;4.1% and 5.7%, respectively. In 728 healthy women, serum CTX concentrations (automated) correlated with those of the manual ELISA (r = 0.82; P &lt;0.0001). The median long-term within-person variability assessed by four repeated measurements over 3 months in 18 postmenopausal women was 9.4%. Compared with 254 premenopausal women, serum CTX was 39% (P &lt;0.0001) higher in 45 perimenopausal women and 86% (P &lt;0.0001) higher in 429 postmenopausal women (mean age, 64 years). Baseline serum CTX correlated negatively with changes of bone mass measured at the mid (r = −0.23; P &lt;0.0001) and distal (r = −0.27; P &lt;0001) radius. Postmenopausal women with serum CTX greater than the mean + 2 SD values in premenopausal women accounted for 42% of the population, lost bone at the mid radius on average eightfold more rapidly than the other women (−0.27% ± 2.92% vs −2.25% ± 3.95%; P &lt;0.0001), and had increased risk of fracture with a relative risk (95% confidence interval) of 1.8 (1.01–3.1) after adjustment for physical activity.

Conclusions: The automated assay for serum CTX is precise and predicts rate of bone loss and fracture risk in postmenopausal women. Because it is convenient to use and has high throughput, this serum bone resorption marker may be useful for the investigation of patients with osteoporosis.

A nonhuman primate model of age-related bone loss: a longitudinal study in male and premenopausal female rhesus monkeys

Aging is associated with gradual bone loss in men and premenopausal women, with an accelerated rate of loss after menopause in women. Although many studies have investigated bone loss due to surgically induced estrogen depletion, little is known regarding normal age-related changes in bone mass in animal models. We used dual-energy X-ray absorptiometry (DXA) to measure bone mineral density (BMD), bone mineral content (BMC), and projected area (PA) at four skeletal sites over 4 years in 20 premenopausal female (8-23 years) and 29 male (8-27 years) rhesus monkeys (Macaca mulatta). Forearm BMD declined with age in both male and female monkeys. Lean mass was positively associated with BMD at all sites in males and with the distal radius in females. Serum osteocalcin declined and urinary cross-links increased with age in males but not females. Serum 25-hydroxyvitamin D concentrations decreased with age in females, and a similar trend was observed in males. In conclusion, an age-related decline in forearm BMD was observed in male and female rhesus monkeys. Total body BMC declined over time in older females, with a similar trend in males. Changes in markers of bone turnover with age were also observed in male monkeys. The results of this longitudinal study suggest that the rhesus monkey is a potential model for age-related changes in the human skeleton.

The role of selective estrogen receptor modulators in the prevention and treatment of osteoporosis

Osteoporosis can affect almost everyone in the population, and although clinical outcome of fracture is manifested in late life, the disease process begins in the early postmenopausal years in women. The pharmacologic agents currently available for osteoporosis prevention and treatment act by inhibiting bone resorption, and include estrogen or hormone replacement therapy (estrogen with progestin), bisphosphonates, salmon calcitonin nasal spray, and selective estrogen receptor modulators (SERMs). Raloxifene is a benzothiophene SERM that has estrogen against effects in bone and on serum lipid metabolism and estrogen antagonist effects on breast and uterine tissue. This article summarizes the effects of these antiresorptive agents, as measured by changes in bone mineral density, biochemical markers of bone turnover, and incident fractures in postmenopausal osteoporosis.

Bone turnover rate in postmenopausal women: bimodal distribution?

There is considerable evidence that elevated bone turnover is an independent form of low bone mineral density (BMD) risk factor of osteoporotic fractures. The aim of our study was to test whether a group of postmenopausal women could be divided into subgroups of high and low bone turnover rate using different pairs of bone turnover markers (one resorption, one formation). Cluster analysis was used to obtain high and low bone turnover subgroups within the study group. A magnitude of difference in lumbar spine BMD (expressed as Z-score) between high- and low-turnover groups was used as a criterion of division success. According to this criterion, the division obtained with a urinary type I collagen crosslinked N-telopeptide/bone alkaline phosphatase pair of markers appeared to be the most significant. This method of separation of two subgroups was highly concordant with the division based on the upper thresholds of the normal values for those markers found for the premenopausal women. It seems that the observed existence of high-and low-turnover subject clusters is not an incidental phenomenon, because the effects obtained for the whole study group were further confirmed by the consistent results of cluster analysis, performed separately for two randomly selected subgroups (A and B) from the study group. The results obtained appear to support the view that bone turnover rate in postmenopausal women is distributed in the bimodal fashion. This finding seems to justify further investigations of more elaborated models, enabling clinicians to individually classify their patients as low- or high-turnover cases with higher efficiency, as in the case of cutoff values for single markers.

Strong prediction of fractures among older adults by the ratio of carboxylated to total serum osteocalcin

We examined serum total osteocalcin (TOC), carboxylated osteocalcin (COC), and their ratio (COC/TOC) by one-step two-site immunofluorescent assays in 87% (n = 792) of all home-dwelling persons of 70 years or older living in a defined area in northern Finland. Other baseline subject-related risk factors of fractures were assessed by postal questionnaires, interviews, clinical examinations, and tests. During a 5-year follow-up period, all falls and fractures (n = 106) were recorded by regular phone calls and by examining all the medical records yearly. Serum TOC and COC concentrations increased with advancing age and were higher in women than in men, but corresponding differences were not found in the case of COC/TOC. The adjusted relative risk of fracture was elevated in association with low (< or =-1 SD from the mean) COC; hazard ratio (HR, 95% CI) 2.00 (1.20-3.36) and low COC/TOC; HR 5.32 (3.26-8.68), the relative risk being highest in the population older than 80 years; and HR 7.02 (2.42-20.39). The predictive value of low COC/TOC lasted 3 years. The multivariable-adjusted relative risk of hip fracture (n = 26) in regard to low COC/TOC ratio was 3.49 (1.12-10.86), as compared with the persons who did not suffer hip fractures. Our results suggest that serum COC concentrations and, more strongly, COC/TOC, predict the occurrence of fractures in older community-dwelling adults. The risk of fracture associated with low COC/TOC equals the hip fracture risk previously verified for concomitant high serum undercarboxylated OC concentrations and low bone mineral density.

Fractures following thyroidectomy in women: a population-based cohort study

Hip fracture risk has been associated with hyperthyroidism and thyroidectomy in men and with hyperthyroidism in women, but the influence of thyroidectomy on fracture risk in women has not been adequately addressed. The 630 Rochester, MN women who underwent thyroidectomy in 1950-1974 were followed subsequently for 12,804 person-years (retrospective cohort study) during which 601 fractures were observed. Relative to incidence rates in the community, there was no increase in overall fracture risk (standardized incidence ratio [SIR] 0.9; 95% confidence interval [CI] 0.8-1.00). No increase was seen in limb fractures generally or in distal forearm fractures specifically (SIR 1.1, 95% CI 0.8-1.4). There was a modest but statistically significant increase in the risk of hip fractures following thyroidectomy (SIR 1.3, 95% CI 1.01-1.8), but much greater increases were apparent in the risk of subsequent fractures of the ribs, spine, and pelvis. There was almost a threefold increase in vertebral fractures (SIR 2.8, 95% CI 2.3-3.3), but the excess was mostly observed long after the original operation and may be attributable to ascertainment bias. Fracture risk was associated with advancing age and with the presence of one or more of the diseases that have been associated with secondary osteoporosis but not with a history of hyperthyroidism, extent of thyroid surgery, or subsequent use of thyroid replacement therapy. Thus, with the exception of some fractures of the axial skeleton, which might have been more completely diagnosed among affected women, there was no increase in fracture risk among women following thyroidectomy performed mainly for adenoma or goiter.

Quantitative genetic analysis of circulating levels of biochemical markers of bone formation

Carboxyterminal propeptide of type 1 collagen (PICP) and bone Gla-protein-osteocalcin (BGP) are the most important components of the organic bone matrix and play a key role in bone formation. To investigate whether and to what extent variation of the plasma levels of these indices of bone turnover depends on genetic factors, we studied 355 adults belonging to nuclear pedigrees. Genetic analysis was carried out in 2 steps: 1) variance decomposition analysis was performed using the FISHER statistical package; and 2) complex segregation analysis implemented in the program package MAN. The effect of age and gender differences, gender hormones, as well as PTH and vitamin-D (calcidiol) plasma levels were evaluated simultaneously with the parameters of variance analysis. The results showed that about 50% of PICP variation is attributable to genetic factors. The effect of age was significant among men and postmenopausal women, whereas calcidiol influenced variation of PICP in premenopausal women. The results of variance analysis showed that some 40% of BGP, adjusted for confounding variables, can be explained in genetic factors. Age and PTH were important covariates for osteocalcin in men and premenopausal women. Exploration of the maximum likelihood estimates of the various hypotheses concerning the mode of intergenerational transmission of PICP and BGP demonstrated a good correspondence to the Mendelian mode of inheritance (i.e., major gene effect).

Effects of soy isoflavones on markers of bone turnover in premenopausal and postmenopausal women

Soy isoflavones are hypothesized to exert hormonal effects in women and thus may play a role in bone metabolism throughout life. In 2 randomized, cross-over studies, 14 pre- and 17 postmenopausal women were given 3 soy protein isolates containing different amounts of isoflavones [control, 0.13; low isoflavone (low-iso), 1.00; and high-iso, 2.01 mg/kg body wt/day, averaging 8, 65, and 130 mg/day, respectively], for over 3 months each. Food records, blood samples, and 24-h urine collections were obtained throughout the studies. The endpoints evaluated included plasma or serum concentrations of bone-specific alkaline phosphatase, osteocalcin, insulin-like growth factor-I (IGFI), IGF binding protein-3 (IGFBP3), and urine concentrations of deoxypyridinoline cross-links and carboxy-terminal telopeptide of type I collagen. In premenopausal women, IGFI and IGFBP3 concentrations were increased by the low-iso diet, and deoxypyridinoline cross-links was increased by both the low- and high-iso diets during certain phases of the menstrual cycle. In postmenopausal women, bone-specific alkaline phosphatase was decreased by both the low- and high-iso diets, and there were trends toward decreased osteocalcin, IGFI, and IGFBP3 concentrations with increasing isoflavone consumption. Although soy isoflavones do affect markers of bone turnover, the changes observed were of small magnitude and not likely to be clinically relevant. These data do not support the hypothesis that dietary isoflavones per se exert beneficial effects on bone turnover in women.

Effect of calcium or 25OH vitamin D3 dietary supplementation on bone loss at the hip in men and women over the age of 60

Dietary supplements that prevent bone loss at the hip and that can be applied safely in the elderly are likely to reduce hip fractures. A daily dietary supplement of 750 mg calcium or 15 microg 25OH vitamin D3 on bone loss at the hip and other sites, bone turnover and calcium-regulating hormones were studied over 4 yr in elderly volunteers using a randomized, double-blind, placebo-controlled trial. Bone mineral density (BMD) was measured by dual x-ray absorptiometry and bone structure by radiographs. Calcium biochemistry and bone turnover markers were measured in blood and urine. The 316 women entering the trial had a mean age of 73.7 yr and the 122 men of 75.9 yr. Baseline median calcium intake was 546 mg/day, and median serum 25OH vitamin D3 was 59 nmol/L. On placebo, loss of BMD at total hip was 2% and femoral medulla expansion was 3% over 4 yr. Calcium reduced bone loss, secondary hyperparathyroidism, and bone turnover. 25OH vitamin D3 was intermediate between placebo and calcium. Fracture rates and drop-out rates were similar among groups, and there were no serious adverse events with either supplement. A calcium supplement of 750 mg/day prevents loss of BMD, reduces femoral medullary expansion, secondary hyperparathyroidism, and high bone turnover. A supplement of 15 microg/day 25OH vitamin D3 is less effective, and because its effects are seen only at low calcium intakes, suggests that its beneficial effect is to reverse calcium insufficiency.

The role of bone turnover markers and risk factors in the assessment of osteoporosis and fracture risk

The clinical evaluation of osteoporosis in individual patients involves confirmation of the diagnosis, the investigation of secondary causes of osteoporosis and the evaluation of subsequent fracture risk. Optimum clinical assessment involves bone mineral densitometry with the treatment thresholds modified by clinical risk factors for individual patients. Bone turnover markers and clinical risk factors can be used to identify patients at risk of osteoporotic fracture and those who have secondary osteoporosis. Risk assessment should involve the evaluation of absolute rather than relative risk. Further work is required to improve the integration of clinical risk factors, bone turnover markers and bone densitometry into appropriate models to enable the assessment of the absolute risk of fracture for individual patients.

Thiazide diuretics affect osteocalcin production in human osteoblasts at the transcription level without affecting vitamin D3 receptors

Besides their natriuretic and calciuretic effect, thiazide diuretics have been shown to decrease bone loss rate and improve bone mineral density. Clinical evidence suggests a specific role of thiazides on osteoblasts, because it reduces serum osteocalcin (OC), an osteoblast-specific protein, yet the mechanisms implicated are unknown. We therefore investigated the role of hydrochlorothiazide (HCTZ) on OC production by the human osteoblast-like cell line MG-63. HCTZ dose-dependently (1-100 microM) inhibited 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-induced OC release by these cells (maximal effect, -40-50% and p < 0.005 by analysis of variance [ANOVA]) as measured by ELISA. This effect of HCTZ on OC release was caused by a direct effect on OC gene expression because Northern blot analysis revealed that OC messenger RNA (mRNA) levels were reduced in the presence of increasing doses of the diuretic (-47.2+/-4.0%; p < 0.0001 by paired ANOVA with 100 microM 13.6+/-0.49 pmol/mg protein/15 minutes; p < 0.05) in MG-63 cells. Reducing extracellular Ca2+ concentration with 0.5 mM EDTA or 0.5 mM ethylene glycol-bis(beta-amino ethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) only partly prevented the inhibitory effect of the diuretic on OC secretion (maximal effect, -22.5+/-6.9%), suggesting that thiazide-dependent Ca2+ influx is not sufficient to elicit the inhibition of OC secretion. Because OC production is strictly dependent on the presence of 1,25(OH)2D3 in human osteoblasts, we next evaluated the possible role of HCTZ on vitamin D3 receptors (VDR) at the mRNA and protein levels. Both Northern and Western blot analyses showed no effect of HCTZ (1-100 microM) on VDR levels. The presence of EGTA in the culture media reduced slightly the VDR mRNA levels under basal condition but this was not modified in the presence of increasing levels of HCTZ. The OC gene promoter also is under the control of transcription factors such as Yin Yang 1 (YY1) and cFOS. Western blot analysis revealed no changes in YY1 levels in response to HCTZ either in the presence or in the absence of 0.5 mM EGTA in the culture media. In contrast, HCTZ induced a dose-dependent increase in cFOS levels (p < 0.002 by ANOVA), a situation prevented by incubation with EGTA. These studies indicate that HCTZ inhibits OC mRNA expression independently of an effect on VDR, YY1, or extracellular Ca2+ levels but involves changes in cFOS levels. As OC retards bone formation/mineralization, the inhibition of OC production by HCTZ could explain its preventive role in bone loss rate.

Biochemical markers and bone mineral density in patients with hip fractures in men

The purpose of this study was to determine whether males with hip fractures have associated decreased gonadal function. Second void urine and serum samples were obtained from 25 male hip fracture patients (mean age+/-SD, 78.5+/-5.9 years) and 19 age- and gender-matched controls (77.6+/-6.2 years). Serum levels of luteinizing hormone (LH), total testosterone (Te), total estradiol (E2), dehydroepiandrosterone sulfate (DHEAS), 1,25(OH)2D3, N-mid osteocalcin (OC(N-mid)), type I collagen degradation products (S-CTx) and urinary levels of pyridinoline (Pyr), deoxypyridinoline (Dpyr) and type I collagen degradation products (U-CTx) were measured. Bone mineral density (BMD) of the L2-4 spine, femoral neck, trochanter, Ward's triangle, distal one third portion of the radius and ultradistal radius were also measured in the fracture group. Serum levels of LH, E2, Te, DHEAS, 1,25(OH)2D3 and OCN-mid in the fracture group were not statistically different from those in the control group. Levels of urinary Pyr, CTx and S-CTx in the fracture group increased significantly compared with those in the control group. In the fracture group, serum levels of Te correlated positively with distal one third portion of the radius BMD and ultradistal radius BMD. U-CTx and S-CTx correlated negatively with all the BMD measurement sites in the hip region and with the radius BMD. An imbalance between bone resorption and bone formation was evident in male hip fracture patients. However, male patients with hip fractures did not show associated decreased gonadal function in this study.