Bone metabolism markers and bone mass in healthy pubertal boys and girls

OBJECTIVE: During puberty, bone growth and mineralization as well as bone turnover increase dramatically. The relation between height velocity and bone turnover is already known, but there are few studies in which both bone metabolism markers and bone mass throughout puberty have been measured. DESIGN: Semi-longitudinal study. In 155 healthy boys (12.0 +/- 1.5 years; range 8.8-15.7 years) and 151 healthy girls (11.2 +/- 1.6 years; range 8.2-14.0 years) markers of bone formation and bone resorption were measured as well as sex steroids, IGF-1 and IGF-BP3, together with bone mineral content (BMC) and bone mineral density (BMD) of the lumbar spine, femur and total body during puberty. All bone measurements were repeated after 1 year. RESULTS: BMC and BMD increased throughout puberty in both sexes. Bone turnover markers increased significantly until maximum values were reached at stage G4 in boys and stage B3 in girls. Height velocity (HV) had a similar changing pattern. Sex steroids and IGF-1 increased and reached adult values at pubertal stage 4. The correlations between bone metabolism markers and BMC were highly significant in boys, while correlations between bone metabolism markers and the increase in BMC over 1 year were significant in both sexes, as was observed for the correlations with HV. CONCLUSIONS: Our data suggest that bone metabolism markers are good predictors of bone mass in boys and of bone mass increase in both sexes. In early puberty, sex steroids stimulate the pubertal growth spurt in conjunction with GH and IGF-1. The fast increase in height gives rise to an increase in bone turnover and bone mineral apposition. It is known that at the end of puberty high levels of oestradiol inhibit chondrocyte proliferation. This leads to a decline in height velocity and bone turnover. Bone mass still increases under the influence of sex steroids and IGF-1. The data in our study confirm previous reports that markers of bone turnover relate positively to height velocity.     

Critical years and stages of puberty for spinal and femoral bone mass accumulation during adolescence

Maximizing peak bone mass is advocated as a way to prevent osteoporosis. As a prerequisite to the elaboration of any preventive program aimed at maximizing peak bone mass, it is important to determine how the rate of skeletal growth at clinically relevant sites, such as lumbar spine and femoral neck, proceeds in relation to age and pubertal stages in both sexes. Bone mass was assessed in 207 healthy caucasian boys and girls, aged 9-18 yr. Bone mineral density (BMD; grams per cm2) and content (BMC; grams) were determined in lumbar spine (L2-L4), femoral neck (FN), and midfemoral shaft (FS), using dual energy x-ray absorptiometry. Bone variables were correlated with both chronological age and pubertal stage, and compared with young adult (20-35 yr) reference values. The main results are: 1) in males, compared to females, there was a marked age-related delay in L2-L4 BMD or BMC increase, but no delay was observed in relation to pubertal stages; 2) at the end of the rapid growth spurt, trends for higher mean values in males were observed for L2-L4 BMC, FN BMD, and particularly FS BMD, but no sex difference was observed for L2-L4 BMD; 3) in females, but not in males, a dramatic reduction in bone mass growth was observed after 15 yr of age, particularly for L2-L4 BMD/BMC and FN BMD. This sharp reduction occurred between the second and fourth years after menarche. In the 14- to 15-yr-old female group, BMD in L2-L4, FN, and FS corresponded to 99.2%, 105.1%, and 94.1%, respectively, and BMC in L2-L4 to 97.6% of the mean values recorded in 20- to 35-yr-old women. In conclusion, this cross-sectional study indicates that during pubertal development, major differences are observed in bone mass growth according to sex and skeletal site. Whereas in males bone mass at different skeletal sites continues to increase substantially between 15-18 yr, skeletal mass growth appears to dramatically slow down at the levels of both lumbar spine and FN at 15-16 yr of age in female adolescents. This suggests that the generally accepted notion that in both males and females bone mass continues to substantially accumulate at all skeletal sites until the fourth decade may not be a constant in human physiology.     

Effects of age, grip strength and smoking on forearm volumetric bone mineral density and bone geometry by peripheral quantitative computed tomography: comparisons between female and male

Peripheral quantitative computed tomography (pQCT) is useful to measure volumetric bone mineral density (vBMD) distinguishing trabecular from cortical bones as well as quantity of bone geometry. In the present study, we examined the effects of age, grip strength and smoking on vBMD, bone geometry and bone strength index (polar strength strain index (SSIp)), and then compared with the differences between female and male by employing pQCT in Japanese 252 female and 230 male subjects. Age was negatively correlated with vBMD, cortical area (Ct.Ar) and cortical thickness (Ct.Th) as well as SSIp in both sexes, and the correlation coefficients were higher in female, compared with those in male. Although age was correlated with endocortical circumferences (En.Le) in both sexes, periosteal circumferences (Ex.Le) were correlated with age only in male. Volumetric BMD, Ct.Ar, Ct.Th and SSIp were significantly lower in the group with vertebral fractures, although En.Le and Ex.Le were similar between subjects with and without vertebral fractures. Grip strength was positively correlated with vBMD, Ct.Ar, Ct.Th as well as SSIp. The extent of correlation was much higher in female, compared with that in male. Ct.vBMD, Ct.Ar, Ct.Th and SSIp, but not trabecular vBMD, were significantly lower in the group with high Brinkman index (number of cigarettes smoked per day) x (duration of smoking (years)) in female. These parameters were not significantly different between groups with high and low Brinkman index in male. In conclusion, the present study demonstrated that age, grip strength and smoking affected forearm vBMD, bone geometry and bone strength index by pQCT. These effects were greater in female, compared with those in male.     

Relationship between leptin levels and bone mineral density in the elderly

OBJECTIVE: To assess the relationship between circulating leptin levels, bone mineral content and density in the elderly. DESIGN: A cross-sectional study. PATIENTS: A cohort of 92 men and 171 women, with ages ranging from 68 to 75 years, selected as a healthy and normal functioning group, in the city centre of Verona. MEASUREMENTS: Plasma leptin levels were determined in each participant. Body composition was evaluated with dual energy X-ray absorptiometry (DXA). Bone mineral content (BMC) and bone mineral density (BMD) were measured at whole-body, hip and femoral neck level in all subjects. RESULTS: In both men and women a significant relationship between fat mass and whole-body BMC or BMD was found. The strength of this association was consistently reduced after adjustment for plasma leptin. A significant association between circulating leptin levels, whole-body, total hip and femoral neck BMC and BMD was found in both sexes. This association retained the statistical significance after adjustment for fat mass percentage, especially in women. In stepwise multiple linear regression analyses, leptin was shown to be a significant predictor of whole-body, total hip and femoral neck BMC and BMD, independently of age and the percentage of body fat in both sexes. The circulating levels of leptin accounted for a variance in whole-body BMC of 8.9% in men and 18.2% in women, and in whole-body BMD of 10.6% in women. CONCLUSION: Our data show a significant relationship between leptin, bone mineral mass and density in healthy elderly men and women.     

X-ray absorptiometry of bone in obese and eutrophic children from Valparaiso, Chile

OBJECTIVE: To assess and compare bone mineral content (BMC) and bone mineral density (BMD) by dual X-ray absorptiometry (DEXA) measurement in obese and eutrophic children. METHODS: In a cross sectional, case control study 16 obese children (8 male, 8 female) aged 5 to 13 years were recruited from the outpatient nutrition clinic of Carlos van Buren Hospital, Valparaiso, Chile, during 1997. Sixteen healthy eutrophic children matched for sex, chronological age, height, and pubertal stage were enrolled as controls. The mean dietary calcium intake was 580 +/- 100 mg/day. All obese patients had more than 2 standard deviation (SD) of height/weight ratio. Lumbar spine (L2-L4) BMD, femoral neck BMD, total body BMD, and total body BMC were measured by posteroanterior dual photon DEXA. The results were expressed as mean +/- SD. Comparison of the data was determined by Wilcoxon and Student t test. RESULTS: Mean BMC was 1684.1 +/- 492.38 g in obese children and 1418.2 +/- 483.48 g in controls (p < 0.001, Student t test; p = 0.001, Wilcoxon test). Mean total BMD was 817.5 +/- 99.37 g/cm2 in obese children and 771.62 +/- 105.62 g/cm2 in controls. (p = 0.041 by Wilcoxon). Mean hip BMD was 784.4 +/- 117.05 g/cm2 in obese children and 801.67 +/- 150.34 g/cm2 in controls. Mean spine BMD was 724.87 +/- 171.75 g/cm2 in obese children and 686 +/- 137.08 g/cm2 in controls (not significant). CONCLUSION: Obese children have more total body BMC than eutrophic children. There was no significant difference in regional hip BMD and lumbar spine BMD among obese and normal children. Obese children may have larger bones.     

Total-body bone mineral content in non-corticosteroid-treated postpubertal females with juvenile rheumatoid arthritis: frequency of osteopenia and contributing factors

OBJECTIVE: To determine the extent of low total-body bone mineral content (BMC) in non-corticosteroid-treated white postpubertal females with juvenile rheumatoid arthritis (JRA) compared with healthy age- and race-matched female controls, and to identify variables that significantly contribute to total-body BMC. METHODS: Thirty-six females with definite JRA who had never received corticosteroids and 51 healthy female controls were evaluated. All subjects had had their first menstrual period at least 2 years prior to enrollment. Total-body BMC, lumbar spine bone mineral density, and body composition were determined by dual x-ray absorptiometry. Total-body BMC Z-scores were calculated for JRA patients using data from controls. JRA patients were dichotomized into those with "normal" bone mass (total-body BMC at or above the mean or no more than 1 SD below the mean) and those with "low" bone mass (total-body BMC more than 1 SD below the mean). Comparisons of anthropometric measurements, laboratory measurements of bone metabolism, disease activity, dietary intake, and physical activity were performed. Stepwise logistic regression was utilized to determine the presence or absence of low total-body BMC and to identify associated contributing factors. RESULTS: Total-body BMC was 4.5% lower in JRA patients than in controls (mean +/- SD 2,050 +/- 379 gm versus 2,143 +/- 308 gm; P = 0.21). Twenty-five of 36 patients (69.4%) had "normal" and 11 of 36 (30.6%) had "low" total-body BMC. Comparison of JRA patients with "normal" versus those with "low" total-body BMC revealed significant differences in disease characteristics, anthropometric and physical development characteristics, laboratory measures of bone mineralization, and dietary intake. The final regression model contained only lean mass (P = 0.01), which accounted for 76.3% of the variance in total-body BMC. The odds ratio for lean mass was 0.4451 (95% confidence interval 0.2374-0.8348). CONCLUSION: In this study, approximately 30% of the subjects in a sample of postpubertal female patients with mild-to-moderate, non-corticosteroid-treated JRA had low bone mass. The predictor variable that significantly contributed to total-body BMC was lean mass, which demonstrated a protective effect of 0.56 risk reduction for low total-body BMC.     

Bone mass and strength: phenotypic and genetic relationship to alcohol preference in P/NP and HAD/LAD rats

BACKGROUND: The association between moderate alcohol intake and elevated bone mineral density observed in several epidemiologic studies might result from common genetic pathway regulating both phenotypes. In this study, we determined whether there is a relationship between alcohol preference and high bone mass or strength and whether bone mass-regulating genes segregate during selective breeding of alcohol preferring rats. METHODS: Six different lines of male rats with high or low preference for alcohol consumption were used in this study. The high alcohol preference lines are alcohol-preferring (P), high-alcohol-drinking 1 (HAD1), and high-alcohol-drinking 2 (HAD2), and their corresponding low alcohol preference lines are alcohol-nonpreferring (NP), low-alcohol-drinking 1 (LAD1), and low-alcohol-drinking 2 (LAD2). Bone mass phenotypes were determined using dual energy x-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and biomechanics in long bones and lumbar vertebrae from rats at 3 and 6 months of age. RESULTS: P rats had significantly higher bone mass and strength compared with NP rats, mainly due to higher cortical bone in long bones and lumbar vertebrae. HAD2 rats also had significantly higher bone mass compared with LAD2 rats, but mostly due to increased trabecular bone leading to increased strength only in lumbar vertebra. Conversely, HAD1 rats had significantly lower bone mass and strength compared with LAD1 rats in long bones. The vertebral bone mass and strength did not differ between HAD1 and LAD1 rats. CONCLUSIONS: This study demonstrated that preference for alcohol consumption had no consistent relationship with high bone mass or strength, as each alcohol-preferring rat line had their unique bone mass phenotypes. However, genes regulating bone mass and strength appear to segregate with alcohol preference genes in P and HAD rat lines, suggesting that alcohol preferring rat lines may be useful for identifying genes that regulate bone mass and structure.     

Timing of peak bone mass: discrepancies between CT and DXA

CONTEXT: The time of life in which peak bone mass in the axial skeleton is attained has been the subject of considerable controversy, with estimates ranging from the time of sexual and skeletal maturity to the fifth decade of life. OBJECTIVE: The objective was to examine whether dual energy x-ray absorptiometry (DXA) and computed tomography (CT) values for bone mass and bone density (BD) in the axial skeleton increase after sexual and skeletal maturity. DESIGN/PARTICIPANTS: Measurements of vertebral bone mineral density and bone mineral content (BMC) by DXA and vertebral BD and BMC by CT were obtained in 50 sexually and skeletally mature white females at baseline and 3 yr later. CT BMC values were calculated through analysis of vertebral volume in relation to density (BMC = vertebral volume x BD). RESULTS: Although neither CT BD nor BMC measures changed with time, DXA bone mineral density and BMC values were significantly higher at follow-up (P < 0.0001). Despite strong correlations between DXA and CT bone measures, DXA yielded greater changes in bone values in 47 of 50 subjects. CONCLUSIONS: Bone acquisition in the lumbar spine as measured by CT reaches its peak by sexual and skeletal maturity. In contrast, bone values by DXA continue to increase after puberty and cessation of longitudinal growth. Increases in DXA measures are likely a reflection of inhomogeneous changes in soft tissues around the spine or of disproportionate increases in the posterior elements of the vertebrae rather than of changes within the vertebral body.     

Clinical and anthropometric correlates of bone mineral acquisition in healthy adolescent girls

We studied the acquisition of bone mineral in 45 healthy prepubertal and pubertal girls and related changes in bone mass to age, body mass, pubertal status, calcium intake, and exercise. A subgroup of 12 girls was followed longitudinally. Bone mineral content (BMC) of the lumbar spine, whole body, and femoral neck was measured by dual energy x-ray absorptiometry and that at the midradius by single photon absorptiometry. For comparison, spine and whole body mineral contents were also measured by dual photon absorptiometry. Bone mass was expressed in conventional terms of BMC and area density (BMD). However, we show that BMD fails to account for differences in bone thickness. Since bone size increases during adolescence, we present a new expression, bone mineral apparent density (BMAD), which is BMC normalized to a derived bone reference volume. This term minimizes the effect of bone geometry and allows comparisons of mineral status among bones of similar shape but different size. BMC increased with age at all sites. These increases were most rapid in the early teens and plateaued after 16 yr of age. When bone mineral values at all sites were regressed against age, height, weight, or pubertal stage, consistent relationships emerged, in which BMC was most strongly correlated, BMD was correlated to an intermediate degree, and BMAD correlated only modestly or without significance. Dietary calcium and exercise level did not correlate significantly with bone mass. From these relationships, we attribute 50% of the pubertal increase in spine mineral and 99% of the change in whole body mineral to bone expansion rather than to an increase in bone mineral per unit volume. In multiple regressions, pubertal stage most consistently predicted mineral status. This study emphasizes the importance of pubertal development and body size as determinants of bone acquisition in girls. BMAD may prove to be particularly useful in studies of bone acquisition during periods of rapid skeletal growth.     

The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats

Growth hormone (GH) is of importance for normal bone remodelling. A recent clinical study demonstrated that MK-677, a member of a class of GH secretagogues (GHSs), increases serum concentrations of biochemical markers of bone formation and bone resorption. The aim of the present study was to investigate whether the GHSs, ipamorelin (IPA) and GH-releasing peptide-6 (GHRP-6), increase bone mineral content (BMC) in young adult female rats. Thirteen-week-old female Sprague-Dawley rats were given IPA (0.5 mg/kg per day; n=7), GHRP-6 (0.5 mg/kg per day; n=8), GH (3.5 mg/kg per day; n=7), or vehicle administered continuously s.c. via osmotic minipumps for 12 weeks. The animals were followed in vivo by dual X-ray absorptiometry (DXA) measurements every 4th week. After the animals were killed, femurs were analysed in vitro by mid-diaphyseal peripheral quantitative computed tomography (pQCT) scans. After this, excised femurs and vertebrae L6 were analysed by the use of Archimedes' principle and by determinations of ash weights. All treatments increased body weight and total tibial and vertebral BMC measured by DXA in vivo compared with vehicle-treated controls. However, total BMC corrected for the increase in body weight (total BMC:body weight ratio) was unaffected. Tibial area bone mineral density (BMD, BMC/area) was increased, but total and vertebral area BMDs were unchanged. The pQCT measurements in vitro revealed that the increase in the cortical BMC was due to an increased cross-sectional bone area, whereas the cortical volumetric BMD was unchanged. Femur and vertebra L6 volumes were increased but no effect was seen on the volumetric BMDs as measured by Archimedes' principle. Ash weight was increased by all treatments, but the mineral concentration was unchanged. We conclude that treatment of adult female rats with the GHSs ipamorelin and GHRP-6 increases BMC as measured by DXA in vivo. The results of in vitro measurements using pQCT and Archimedes' principle, in addition to ash weight determinations, show that the increases in cortical and total BMC were due to an increased growth of the bones with increased bone dimensions, whereas the volumetric BMD was unchanged.     

Effects of dietary restriction on total body, femoral, and vertebral bone in SENCAR, C57BL/6, and DBA/2 mice

Dietary restriction (DR) increases the life span and retards aging, in part, by limiting free radical generation and oxidative damage. DR also reduces body mass, a major determinant of bone mass across the life span. We tested the hypothesis that DR has its most beneficial effects on bone in mouse strains with high free radical generation (sensitive to carcinogenesis [SENCAR] > C57 > DBA) versus the hypothesis that bone mass at weight-bearing sites is determined by body mass in DR and ad libitum (AL)-fed mice. Male mice of each strain were killed at 10 weeks of age (t(0)) or randomized to an AL-fed or 30% DR feeding regimen for 6 months. Food consumption by AL-fed mice was measured daily, and DR mice received 70% of the amount of food consumed by their respective AL-fed mice the previous day. Body fat (%) and bone mineral density (BMD) and content (BMC) were determined by PIXImus densitometry. There were strain-dependent effects on body mass, crown-to-rump length, percent body fat, and total body, femoral, and vertebral BMD and BMC under all conditions. SENCAR mice were heavier, longer, had larger bones, and generally exhibited higher total body, femoral, and vertebral BMC and BMD than C57 and DBA mice. DR had beneficial effects on BMD and BMC in the vertebrae of the SENCAR mouse model of high free radical generation and in the obese, diabetes-prone C57 mouse model of high end-stage protein glycation. DR DBA and SENCAR mice had lower femoral BMDs and BMCs than their respective AL-fed controls. Regression analysis confirmed linear relationships between total and lean body mass and total body and femoral BMDs and BMCs, suggesting that physiologic adaptation to a lower body mass accounts for the lower femoral bone mineral values observed in DR versus AL-fed mice. Thus, both hypotheses are, at least, partially valid. DR is beneficial in the trabeculae-rich vertebrae of animal models of high oxidant stress, and total/lean body mass determines BMD and BMC in the weight-bearing femur in DR and AL-fed mice.     

女性腰椎峰值骨量与骨骼大小的关系

目的　了解女性腰椎骨骼大小对峰值骨密度 (BMD)的影响。方法　采用QDR 450 0A型扇形束DXA骨密度仪 ,测量 52 7例年龄 2 5～ 3 9岁健康女性前后位 (正位AP)腰椎 1～ 4椎体和侧位 (Lat)腰椎 2～ 4椎体的投射骨面积 (BA)、骨矿含量 (BMC)和面积BMD(aBMD)及AP/Lat相伴扫描测量腰椎的体积BMD(vBMD)。用直线和多元线性回归分析骨量与BA、身高和体重之间的关系。按不同BA分组 ,了解各组之间骨量的差异。结果　BA与BMC(r =0 .79和 0 .78,均P <0 .0 1)和aBMD(r =0 .40和 0 .3 8,均P<0 .0 0 1)呈正相关 ,Lat BA与vBMD相关有显著意义 (r =0 .14 ,P <0 .0 1)。AP BA每变化 1个标准差 ,AP BMC和AP aBMD在平均值的基础上分别相应变化 13 .1%和 4.47% ;Lat BA每变化 1个标准差 ,Lat BMC、Lat aBMD和vBMD在平均值的基础上分别相应变化 13 .3 %、4.4%和 1.5% ;AP BA的全距变化所致AP BMC和AP aBMD的变化分别约为 78.6%和 2 6.8% ,Lat BA的全距变化所致Lat BMC、Lat aBMD和vBMD的变化分别约为 79.8%、2 6.3 %和 8.94%。不同BA组之间的身高、体重、BMC和aBMD均具有非常显著性意义 (均P <0 .0 0 1)。影响BA、BMC和Lat aBMD的主要因素为身高 ,影响AP aBMD的主要因素为体重。结论　BMC除以BA不能完全消除骨骼大小对aBMD的影响     

The bone mass concept: problems in short stature

Bone densitometry is currently one of the mainstays in the evaluation of systemic bone diseases in adults and is also increasingly used to assess primary or secondary bone disorders in children and adolescents. The purpose of carrying out densitometric studies in such circumstances is to measure the densitometric indicators of bone stability. Following procedures which were established for diagnosing adult osteoporosis, a decrease in densitometric surrogates of bone stability is usually interpreted as indicating increased fracture risk. The most basic densitometric parameter is bone mineral content (BMC), which can be measured with most densitometric techniques. BMC is either defined as the mass of mineral contained in an entire bone or as the mass of mineral per unit bone length. While mineral mass can be expected to be a good surrogate for bone stability, BMC is obviously a size-dependent parameter, since small bones weigh less than big bones. This is a drawback in paediatric use, since many children and adolescents who are examined by densitometry suffer from chronic disorders and are small-for-age. Short children will have a lower BMC than their healthy age-matched peers, even if their (smaller) bones are otherwise completely normal.     

Weight gain and restoration of menses as predictors of bone mineral density change in adolescent girls with anorexia nervosa-1

CONTEXT: Adolescents with anorexia nervosa (AN) have low bone mineral density. However, the effect of disease recovery, first, on bone density measures assessed using the Molgaard approach, which differentiates between reported low bone density resulting from short bones (based on height Z-scores) and that resulting from thin bones [based on measures of bone area (BA) for height] or light bones [based on measures of bone mineral content (BMC) for BA]; and second, on height-adjusted bone density measures, has not been well characterized. We hypothesized that menstrual recovery and weight gain (> or =10% increase in body mass index) would predict an increase in these measures of bone density. METHODS: In a prospective observational study, lumbar and whole-body (WB) bone density was measured at 0, 6, and 12 months in 34 AN girls aged 12-18 yr and 33 controls. Using Ward's modification of the Molgaard approach, we determined measures of BMC for BA and BA for height at the lumbar spine and WB and also determined spine bone mineral apparent density and WB BMC adjusted for height. RESULTS: Girls with AN had lower spine BMC for BA Z-scores (P = 0.0009), and lower WB BA for height Z (P < 0.0001), compared with controls. Menstrual recovery and weight gain in AN (AN-recovered) (median 9 months) resulted in a stabilization of BMD measures, whereas BMD continued to decrease in AN who did not gain weight and recover menses (AN-not recovered). AN-recovered also predicted greater increases in spine BMC for BA and WB BA for height, compared with AN-not recovered (P < 0.05). CONCLUSIONS: Even short-term weight gain with menstrual recovery is associated with a stabilization of BMD measures.     

Significance of body weight status for bone density in the elderly and very old

Reduced bone density and osteoporosis are significant health problems and contributors to disability and mortality among older women and men. Therefore the decline of bone mineral content (BMC) and bone mineral density (BMD) are aspects of ageing with great medical and social significance. In recent years a low body weight was declared to be an important risk factor for the development of osteoporosis. In the present study the impact of weight status, defined by the categories of the WHO, on BMC of the whole body and BMD of the proximal femur end, determined by dual energy x-ray absorptiometry (DEXA), were studied in 77 female and 62 male probands aged between 60 and 92 years (x = 71.7 yrs). With increasing weight status (BMI categories), BMC and BMD increased significantly (p < 0.001). This was true of both sexes. Even moderate overweight women and men (BMI 25.0-29.99) showed a significantly higher bone density than their normal weight counterparts (BMI < 25.0). In the present study a marked positive impact of body weight on bone density of old-aged women and men could be shown.     

The relationship between sex steroids and bone mineral content in women soon after the menopause

Prevention of postmenopausal osteoporosis is now possible with current therapy, if initiated soon after the menopause and continued for at least 10 years. Simple ways of detecting those at risk of subsequent osteoporosis are urgently needed. This study investigated the hypothesis that certain serum sex hormones could predict bone mineral content (BMC) as measured by dual photon densitometry, soon after the menopause. The subjects included 136 healthy white females within 30 months of their last menstrual period with a mean age of 52 years. Of the sex hormones, the adrenal androgen dehydroepiandrosterone sulphate (DHEAS) correlated best with spinal BMC, a relationship which was significant using multiple regression (P = 0.02), although the correlation was weak (r = +0.19). A direct physiological role for DHEAS has yet to be found, despite being present in large quantities in serum, although it may act as a marker for other processes. No association was seen between testosterone, sex hormone binding globulin, oestradiol, oestrone and oestrone sulphate and spinal BMC. No significant correlations with any hormones were seen with femoral BMC. The data suggest that serum sex hormones are not useful markers of current bone mineral status soon after the menopause, although further work is needed to explore the relationship with DHEAS.     

Bone mineral content and bone mineral density at lumbar spine and forearm in Chinese girls aged 6-18 years

We investigated the age-related bone mineral content (BMC), bone mineral density (BMD) and the tempo of growth in BMC and BMD at lumbar spine and forearm in 455 Chinese girls aged 6-18 yr. BMC and BMD at the anteroposterior lumbar spine (LS), the left forearm (radius+ulna ultradistal, R+UUD) and one-third region (R+U1/3) were measured using a dual-energy X-ray bone densitometer (DXA). BMC and BMD exhibited different change patterns with the age changes. There were significant correlations between age, height, weight and BMC and BMD at LS, R+UUD and R+U1/3 sites. BMC and BMD increased significantly with increments in pubertal stages at LS, R+UUD and R+U1/3 sites. In conclusion, our study showed that Tanner stage had a significant positive association with BMC and BMD of the lumbar spine and forearm. The differences were found in the growth tempo of BMC and BMD within a region and between the spine and forearm. Both BMD and BMC were recommended to evaluate the bone health in children and adolescents.     

Longitudinal monitoring of bone mass accumulation in healthy adolescents: evidence for a marked reduction after 16 years of age at the levels of lumbar spine and femoral neck in female subjects.

The amount of skeletal mass acquired during adolescence is one of the most important determinants for the risk of postmenopausal and involutional osteoporosis. In both sexes, a large variance in bone mineral density (BMD) and content (BMC) is observed among healthy individuals at the beginning of the third decade. To determine the crucial pubertal years during which bone mass accumulation mainly occurs, we longitudinally monitored the gain in BMD/BMC at clinically important sites, such as lumbar spine and femoral neck, with respect to osteoporotic fracture risk. The changes in BMD (grams per cm2) and BMC (grams) were determined at 1-yr intervals at the level of lumbar spine vertebrae (L2-L4), femoral neck, and midfemoral shaft, using dual energy x-ray absorptiometry (Hologic QDR 1000), in 198 healthy adolescents (98 females and 100 males), aged 9-19 yr. Mean daily energy and calcium intakes, height, weight, and body mass index of the studied cohort were within the normal range for age. In females, the increment rate in BMD/BMC was particularly pronounced over a 3-yr period, i.e. from 11-14 yr of age. This increment dramatically fell after 16 yr and/or 2 yr after menarche. The mean gains in lumbar, femoral neck, and midfemoral shaft BMD were not statistically significant between 17-20 yr. In males, the gain in BMD/BMC was particularly high over a 4-yr period, i.e. from 13-17 yr. Then the increment rate markedly declined, but remained significant between 17-20 yr for L2-L4 BMD/BMC and midfemoral shaft BMD. In contrast, no significant increase was observed for femoral neck BMD. An impressive interindividual variation was observed between the yearly height increment and the bone mass accumulation. The bone mass-height gains relationship during puberty evolved according to a loop pattern, with maximal variance at Tanner stages P3-P4. This longitudinal study delineates the crucial pubertal years during which the skeletal mass accumulates at high, but various, rates at skeletal sites where the consequences of the osteoporosis are particularly dramatic. Furthermore, the results indicate that in a cohort of healthy females with apparently adequate intakes of energy and calcium, bone mass accumulation is drastically reduced by 16 yr of age in both lumbar spine and femoral neck.     

A two-year prospective controlled study of bone mass and bone turnover in children with early juvenile idiopathic arthritis

OBJECTIVE: To explore early changes and predictors of bone mass in children with juvenile idiopathic arthritis (JIA) in order to identify patients who will develop bone mass reductions. METHODS: We conducted a prospective cohort study of 108 children with early JIA (ages 6-18 years; mean disease duration 19.3 months) who were individually matched with 108 healthy children for age, sex, race, and county of residence. Bone mass and changes in total body, spine, femur, and forearm bone mineral density and bone mineral content (BMC), body composition, growth, and biochemical parameters of bone turnover were examined at baseline and at followup a mean of 24 months later. Low bone mass was defined as a Z score >1 SD below the reference population. RESULTS: Of the 200 children evaluated at followup, the 100 healthy children had greater gains in total body BMC (P = 0.035), distal radius BMC (P < 0.001), and total body lean mass (P < 0.001) than did the 100 JIA patients. Low or very low total body BMC was observed in 24% of the patients and 12% of the healthy children. Bone formation, bone resorption, and weight-bearing activities were reduced in the patients compared with the healthy children. Multiple regression analysis showed that in patients with JIA, serum bone-specific alkaline phosphatase, serum C-telopeptide of type I collagen, and weight-bearing activities were independent predictors of changes in total body BMC. Total body BMC was lower in patients with polyarticular onset than in those with oligoarticular disease onset. CONCLUSION: Patients with JIA have moderate reductions in bone mass gains, bone turnover, and total body lean mass early in the disease course.     

Effects of treatment with ibandronate on bone mass,architecture, biomechanical properties,and bone concentration of ibandronate in ovariectomized aged rats

OBJECTIVE: To investigate the effects of treatment with ibandronate, a highly potent nitrogen-containing bisphosphonate, on bone loss, bone quality, biomechanical properties, and bone concentrations in aged ovariectomized rats. METHODS: Eight-month-old female Wistar rats were ovariectomized (Ovx) or sham-operated. Treatment was started 10 weeks following Ovx with subcutaneous ibandronate in doses of 0.2, 1.0, 5.0, or 25 micro g/kg/day for 12 mo. Additional groups received 25 or 125 micro g/kg intermittently every 25 days, resulting in the same total dose as compared to 1.0 or 5.0 micro g/kg/day, respectively. Bone analyses by x-ray densitometry, peripheral quantitative computed tomography (pQCT), dual energy x-ray absorptiometry (DEXA), histomorphometry, 3-point bending, and compression tests were performed in femora, tibiae, and lumbar vertebrae in separate groups at the beginning and the end of treatment. Ibandronate concentration in tibiae and vertebrae was determined by gas chromatography mass spectroscopy at the end of the study. RESULTS: Ovariectomy resulted in a significant reduction in bone mass (p 相似文献