Biochemical markers as predictors of rates of bone loss after menopause

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.

Management of osteoporosis due to ovarian failure

The management of oestrogen deficiency bone loss needs to include general measures to protect against osteoporosis, the identification and treatment of other reversible causes of bone loss, and the use of proven agents for the treatment of osteoporosis. The general measures include improved physical activity, adequate diet (paying particular attention to calcium and vitamin D), and avoidance of behaviours that promote bone loss, such as smoking and alcohol abuse. The diseases that should be identified, other than estrogen-deficiency, include primary hyperparathyroidism, thyrotoxicosis and celiac disease. The treatments that are proven to prevent fractures in women with estrogen deficiency, include hormone replacement therapy, raloxifene, nasal calcitonin, bisphosphonates, (alendronate and risedronate) and parathyroid hormone. The most appropriate therapy in the younger woman is HRT, although the trial-based evidence that HRT prevents fractures is not strong. There is a wide choice of preparations and the use of continuous combined preparations avoids regular menstrual periods, one of the limitations to the use of HRT. Raloxifene has less effect on bone mineral density than HRT, but a similar effect on vertebral fractures and does not result in menstrual bleeding or increased risk of breast cancer. There is recent evidence suggesting that the beneficial effects on lipids translate into reduced risk of cardiovascular disease. Bisphosphonates are the standard treatment for the older woman with osteoporosis. Alendronate has been found to reduce the risk of spine, hip, and wrist fractures and has approval for a once weekly regimen, an approach that appears to prevent GI side effects. Risedronate reduces the risk of spine and non-vertebral fractures within the first year of treatment and has been shown to reduce the risk of hip fracture. It has not been associated with an excess of GI side effects. Parathyroid hormone therapy results in increases in BMD that are even greater than estrogen and the bisphosphonates and to an even greater reduction in the risk of fractures, particularly non-vertebral fractures. It works by stimulation of bone formation rather than by inhibition of bone resorption. However, it has to be given by daily injection. Thus, we have a wide choice of therapies for the woman with osteoporosis due to ovarian failure.

Age-related thymic involution in C57BL/6J x DBA/2J recombinant-inbred mice maps to mouse chromosomes 9 and 10

A comprehensive analysis of initial thymus size and involution rate has not been quantitated for different genetic backgrounds of mice, thus genetic linkage analysis of thymic involution has not been possible. Here, we have used a mathematical method to analyze the age-related decline in thymocyte count in C57BL/6 and DBA/2 mice and have observed that thymic involution could be best fit with a negative exponential curve N(t)=beta(0) x exp(-beta(1)t), where t represents the age (day). This regression model was applied to C57BL/6 x DBA/2 (B x D) recombinant inbred strains of mice to identify the genetic loci influencing age-related thymic involution. There was a dramatic genetic effect of B and D alleles on thymocyte count at young age and the age-related thymic involution rate. The strongest quantitative trait loci (QTL) influencing the rate of thymic involution were mapped to mouse chromosome (Chr) 9 (D9Mit20 at 62 cM) and Chr 10 (D10Mit61 at 32 cM). The strongest QTLs influencing the initial thymocyte count were mapped to ChrX (DXMit324 at 26.5 cM) and Chr 3 (D3Mit127 at 70.3 cM). The present study suggests that the initial thymus size and the rate of thymic involution may be influenced by a relatively small number of genetic loci.

Identification of novel proteolytic forms of osteocalcin in human urine

In this study, we report the isolation and characterization of osteocalcin in human urine using mass spectrometry and N-terminal sequencing. Multiple proteolytic forms of osteocalcin were found, which consisted of 16-27 residues from the middle region of the molecule. Several fragments had residue Gly7 at the N-terminus and the most predominant was fragment 7-31. Additional fragments starting from residue Asp14 were detected in the samples of children and young adults. Immunochemical detection of urine osteocalcin fragments had a statistically significant negative correlation to bone mineral density in evaluation of urine samples from 75-year-old women. Thus, the measurement of osteocalcin fragments in urine may have potential applications in diagnostics related to disorders of bone metabolism.

Osteoporosis considerations in the frail elderly

Osteoporosis is a growing public health problem throughout the world, in part because of the increasing numbers of people living beyond the age of 65 years. Skeletal fractures are the clinical manifestation of the disease, with older patients the most severely affected. Conditions associated with frailty such as falls and reduced muscle strength likely contribute to fractures, causing substantial mortality, morbidity, and economic cost. Screening guidelines for osteoporosis have been issued recently and take into account multiple risk factors for this condition. Falls are the chief mechanism by which osteoporotic fractures occur. Nonpharmacologic interventions for osteoporosis mainly address fall and frailty prevention, whereas pharmacologic interventions target bone loss through decreasing bone resorption, increasing bone formation, or a combination of both processes. Although guidelines for intervention strategies are in flux, it is now suggested that absolute fracture risk rather than diagnostic thresholds be used to determine the timing for therapeutic intervention. Individual risks and benefits of therapies need to be considered before choosing a therapeutic regimen.

Vitamin D and attainment of peak bone mass among peripubertal Finnish girls: a 3-y prospective study

BACKGROUND

Little is known about the effect of vitamin D status on bone gain in adolescents.

OBJECTIVE

The objective was to examine whether vitamin D status is associated with accrual of bone mineral density (BMD) and bone mineral apparent density (BMAD).

DESIGN

This 3-y prospective study examined the association between changes in BMD or BMAD and serum 25-hydroxyvitamin D [25(OH)D] in 171 healthy Finnish girls aged 9-15 y. Lumbar spine and femoral neck BMDs were measured by dual-energy X-ray absorptiometry.

RESULTS

Baseline 25(OH)D correlated significantly with the unadjusted 3-y change in BMD at the lumbar spine (r = 0.35, P < 0.001) and femoral neck (r = 0.32, P < 0.001) in all participants. The difference from baseline in adjusted 3-y BMD accumulation between those with severe hypovitaminosis D [25(OH)D < 20 nmol/L] and those with a normal vitamin D status [25(OH)D > or = 37.5 nmol/L] was 4% (12.7%, 13.1%, and 16.7% for the lowest, middle, and highest tertiles of 25(OH)D, respectively; P for trend = 0.01) at the lumbar spine in the girls with advanced sexual maturation at baseline (n = 129). Moreover, the adjusted change in lumbar spine BMD was 27% greater in the highest vitamin D intake tertile than in the lowest tertile in the same girls (P for trend = 0.016).

CONCLUSIONS

Pubertal girls with hypovitaminosis D seem to be at risk of not reaching maximum peak bone mass, particularly at the lumbar spine. Dietary enrichment or supplementation with vitamin D should be considered to ensure an adequate vitamin D status.

Understanding the physiological and functional consequences of menopause: the PROSALMEN study. PROgetto SALute MENopausa

BACKGROUND AND AIMS

Women live longer and are more often affected by disability and poor health than men. The mechanism underlying this sex-related "mortality-morbidity" paradox is still unclear but it has been suggested that the physiological and functional changes occurring during the menopausal transition play an important role. The aim of PROSALMEN (PROgetto SALute MENopausa: Health in Menopause Project) is to study in great detail how these changes affect the integrity and function of the physiologic subsystems that are relevant to the maintenance of an active and healthy life-style during the aging process.

METHODS

PROSALMEN is a cross-sectional comparison of age-matched pre- and post-menopausal women. Thirty post-menopausal women, aged 48-58 years, were enrolled in the study together with 30 age-matched pre-menopausal controls. A number of clinical, biological and functional parameters were collected assessing the integrity and level of function of the physiological subsystems that are important for mobility. Furthermore, we collected information on risk factors, medical conditions and symptoms that frequently develop or become clinically evident after menopause, including the most important elements of the classical post-menopausal syndrome.

CONCLUSIONS

This rich dataset will be used to start dissecting the causal pathway leading from menopause to damages in the musculoskeletal system and, in turn, to reduced physical function. The final goal is to understand how and to what extent changes in health behavior and pharmacological treatments in addition to hormone replacement therapy (HRT) may counteract these processes.

Changes of biochemical bone markers during the menopausal transition

We present data on the changes of the bone formation markers osteocalcin (OC), bone-specific alkaline phosphatase (bone ALP) and bone sialoprotein (BSP), as well as the resorption markers pyridinoline (PYD), deoxypyridinoline (DPD), C- and N-terminal telopeptide cross-linked collagen type I (CTX, NTX), and tartrate-resistant acid phosphatase type 5b (TRACP) at five time points during the course of two years in healthy premenopausal, perimenopausal and early postmenopausal women. The prospective study showed that CTX (p<0.001), NTX (p=0.001) and TRACP (p=0.001), as well as bone ALP (p=0.009) and OC (p=0.052), were significantly increased already in the transition period from peri- to postmenopause. The pyridinium crosslinks indicated an increased collagen degradation rate already in the perimenopause (PYD, p=0.017; DPD, p=0.054). Significant inverse correlations with the two years changes of the bone mineral density were found for bone ALP, CTX, OC and DPD in the perimenopausal group. The measurement of a comprehensive panel of biochemical bone markers clearly shows that metabolic changes in bone metabolism appear pronounced in the perimenopause, a period still presenting satisfactory estrogen supply. Thus, the perimenopause is an important phase for a contingent development of osteoporosis.

Critical differences in the serial measurement of three biochemical markers of bone turnover in the sera of pre- and postmenopausal women

OBJECTIVES

The purpose of this investigation was to quantify the biologic, day-to-day variability and critical differences in serum levels of crosslinked collagen N-telopeptides (NTx), procollagen aminoterminal extension propeptides (PINP) and bone specific alkaline phosphatase (bAP) in healthy women.

DESIGN AND METHODS

Seven blood samples were collected from 12 pre- and 15 postmenopausal women over 4 to 6 months. NTx, PINP and bAP levels were determined utilizing enzyme- and radioimmunoassay techniques.

RESULTS

The within-subject coefficient of variation (C.V.) in serum bAP, NTx and PINP levels was 7.1, 10.6 and 12.4% respectively. These variances did not differ significantly among premenopausal women when compared with postmenopausal subjects. Combining terms for analytical and biologic variability revealed that a critical difference between 2 successive serial measurements is 24% for bAP, 34% for NTx and 38% for PINP.

CONCLUSION

Circulating levels of NTx, PINP and bAP are stable over time periods of several months, allowing for the determination of significant changes in skeletal metabolism of women.