Critical years and stages of puberty for radial bone mass apposition during adolescence.

The acquisition of radial mineral density was evaluated in relation to anthropometric characteristics, menarche status, calcium intake and physical activity in a healthy young female population (200 girls and 100 women, respectively aged 11-16 yrs and 20-24 yrs) living in an area of Southern Italy. We performed bone mineral density (BMD) by dual energy X-ray absorptiometry on the ultradistal and middistal radius. Dietary calcium intake was evaluated by a detailed Food Frequency Questionnaire and confirmed by a 3-day record. A questionnaire on energy expenditure was used to assess physical activity in each participant. Morning blood samples were drawn from fasting girls to measure 25-hydroxycalciferol (25 OH-D). We found current calcium above the levels reported by Recommended Dietary Allowances (RDA) in only 31% of women and 6% of girls. BMD steadily increased up to the age of 16 and was increased in postmenarcheal girls compared to premenarcheals of the same pubertal stage. Bone density was also significantly related to age, weight and height in postmenarcheal adolescents, while in girls before and after menarche, no relation was observed between radial BMD and calcium intake or physical activity. In the presence of comparable calcium-intake values recorded in pre- and in postmenarcheal girls, the latter subgroup displayed a marked increase of 25 OH-D serum levels. Our study revealed a calcium intake lower than the RDA in a large percentage of healthy girls and young women, and emphasized the importance of menarche occurrence in bone mass acquisition during pubertal development.     

Analysis of bone mineral density and turnover in patients with cystic fibrosis: associations between the IGF system and inflammatory cytokines

BACKGROUND: Cystic fibrosis (CF) patients present an increased risk of osteoporosis, and increased fracture rate. Several factors have been identified as modulators of bone metabolism and bone mineral density (BMD). AIMS: To evaluate BMD and serum markers of bone turnover and establish their relationships with serum concentrations of interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha, IGF-I, IGF-II, IGF binding protein (IGFBP)-2, IGFBP-3, and parathyroid hormone (PTH) in young adult CF patients. METHODS: Seventeen young adult CF patients (4 M, 13 F; mean age: 26.6 +/- 1.1 years) were enrolled in the study and analysed as a whole and as two subgroups according to the Shwachman-Kulczycki score. BMD was assessed at the lumbar spine (L1-L4) by dual energy X-ray absorptiometry (DXA Hologic QDR 2000). Bone turnover was assessed by measuring serum levels of osteocalcin (OC) and serum carboxyterminal propeptide of type I collagen (PICP) as markers of bone formation, and serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) as a marker of bone resorption. Serum IGFs, IGFBPs, and cytokines were assayed using special commercial kits. Daily calcium intake and weekly physical activity were estimated by questionnaires. Forced expiratory volume in one second was used to assess pulmonary function. RESULTS: Lumbar BMD was normal, although there was a tendency to be lower in the patients with a lower clinical score. Both OC and PICP were increased, whereas ICTP was normal. Lumbar BMD was positively correlated with pulmonary function. IL-6 and C-reactive protein (markers of inflammation) were inversely correlated with PICP. Serum ICTP levels were correlated with serum IGF-I levels.No significant relationship was detected among lumbar BMD, markers of bone turnover and PTH, IGF-I, IGF-II, IGFBP-2, IGFBP-3, TNF-alpha, IL-1beta, and body mass index Z-score. CONCLUSIONS: Bone turnover is abnormal in CF patients. Young adult CF patients with satisfying clinical status and nutritional conditions have normal BMD and increased serum OC and PICP levels.     

Early Initiation of Smoking and Alcohol Drinking as a Predictor of Lower Forearm Bone Mineral Density in Late Adolescence: A Cohort Study in Girls

Background

Adolescence is a critical stage for bone accrual. It is also decisive for the establishment of behaviors such as smoking and alcohol drinking.

Objective

To quantify the short- and long-term associations between smoking and drinking initiation and bone mineral density in adolescent girls.

Methods

We used prospective data from 731 girls identified in public and private schools in Porto, Portugal. Evaluations were conducted when participants were 13 and 17 years old. Bone mineral density (BMD) was measured at the forearm by dual-energy X-ray absorptiometry and weight, height and fat-free mass were measured. Pubertal development status was estimated using menarche age. Self-administered questionnaires were used to collect data on smoking and alcohol drinking, physical exercise and calcium and vitamin D intakes. BMD in early and late adolescence was analyzed as a continuous or dichotomous (Z-score cutoff: −1.0) variable. Associations were calculated using linear or logistic regression.

Results

Over one quarter of these girls had tried smoking by 13, while 59% had drunk alcoholic beverages and 20% had experienced both behaviors by that age. Lower mean BMD at 17 years of age was observed in girls who had ever smoked by 13, as well as in those who reported drinking at that age. There were no significant cross-sectional associations between experience and frequency of smoking or drinking and BMD at 13 years of age. However, we observed significant associations between BMD z-score<−1 in late adolescence and having ever smoked by 13, after adjustment for menarche age and sports practice, (OR = 1.92; 95% CI: 1.21, 3.05) and with ever smoking and drinking in the same period (OR = 2.33; 95% CI: 1.36, 4.00).

Conclusion

Our study adds prospective evidence to the role of early initiation of smoking and alcohol drinking as relevant markers of lower bone mineral density in late adolescence.     

INTAKES OF SELECTED NUTRIENTS,BONE MINERALISATION AND DENSITY OF ADOLESCENT FEMALE SWIMMERS OVER A THREE-YEAR PERIOD

The aim of this study was to conduct three-year monitoring of bone mineralization (BMC) and bone mineral density (BMD) of adolescent girls engaged in swimming at the time of attaining the peak bone mass and of their counterparts leading a rather sedentary life, considering the intakes of calcium, phosphorus and protein, as well as the proportions among those nutrients. Two groups of girls aged 11–13 years were studied 3 times at yearly intervals: untrained controls (n = 20) and those engaged in competitive swimming (n = 20). Bone density was determined by dual-energy X-ray absorptiometry (DXA) in the lumbar spine (L2 – L4). Nutrient intakes (energy, protein, calcium, phosphorus) were assessed from 24-h recalls. The group of swimmers had significantly lower BMI values than the control group. No systematic, significant between-group differences were found in nutrient intake or in bone mineralization variables. Calcium intake was below the recommended norm in all subjects but mean values of bone mineralization variables (BMC, BMD) steadily increased in both groups. The BMD z-scores proved negative throughout the three-year period of early adolescence in both groups of girls and that decrease was significant in swimmers. This could have been due to insufficient calcium intake as well as to inadequate calcium-to-phosphate and protein-to-calcium ratios and, when continued, might result in a decreased bone mass in adulthood.     

Zinc status and bone mineralisation in adolescent girls.

The aim of the project was to assess the relationship between zinc status and bone mineralisation in pre-menarcheal adolescent girls. One hundred and thirty-nine healthy pre-menarcheal girls (Tanner pubic hair stage < or = 4), aged 12.4 +/- 1.0 years, had two visits at an interval of 2 years. Serum and urine zinc concentrations (Zn S; Zn U; Zn U/ creatinine), insulin-like growth factor 1 (IGF-I), and markers of bone turn-over, i.e. osteocalcin and parathormone (PTH), concentrations were measured at the first visit. Lumbar (L2-L4) bone mineral content and density (BMC, BMD) were measured at both visits. BMC and BMD and their increase at the follow-up after 2 years were compared with biochemical data by multiple regression. The stage of puberty was added as a covariable in the analysis. At the first visit, a significant correlation was found between sexual maturity and initial BMC, BMD, height, weight, and IGF-I. Zn S was negatively correlated with osteocalcin. Zn U showed a positive correlation with BMC, BMD, IGF-I, height, weight, and PTH. At the second visit, sexual maturity showed a positive correlation with BMD and weight increments and a negative one with BMC and height gains. Zn S was significantly related with BMD increase. These correlations suggest that zinc plays a role in normal growth and bone mineralisation during puberty onset.     

Effect of low or high dietary calcium on the morphology of the rat femur

The present study compared the effect of a calcium deficit or surfeit on femurs. Young female rats were fed with the normal (1.18%), low (0.05%), or high (2.00%) calcium diet for 3, 7, 15 or 30 days. Two groups received the low calcium diet for the first 15 days and then were followed by the normal (L-N) or high calcium diets (L-H) for the sequential 15 days. The morphology of the femur was studied together with serum calcium, parathyroid hormone (PTH), calcitonin and bone mineral density (BMD). We did not find any significant changes in the serum PTH level and bone morphology in the high calcium group. In the low calcium group, the serum PTH level increased, BMD of the whole body, the femoral weight and the femoral trabecular bone decreased as compared with the normal calcium group. There was a greater proportion of resorbing surface, less resting surface and larger vascular canal openings in the femoral endosteal surfaces in the low calcium group. In the L-N or L-H group, the femoral trabecular bone increased and the femoral resorbing surface decreased as compared with those of the low calcium group. These findings suggest that high calcium intakes do not affect the bone mass, and low calcium intakes have a deleterious effect on bone status, which may be related to vascular alternations of the bone. Reversing the low income calcium intake by a higher calcium diet can partially improve the bone alternations induced by low calcium intake.     

Intake of Dairy Products,Calcium, Magnesium,and Phosphorus in Childhood and Age at Menarche in the Tehran Lipid and Glucose Study

Purpose

Studies indicate that milk intake is associated with insulin-like growth factor 1 (IGF-1) concentrations and height in childhood, whether milk and other dairy products promote puberty remains unclear. This study aimed to investigate influences of pre-pubertal intakes of milk, yogurt and cheese on menarcheal age in Tehranian girls. The associations of total dietary calcium (Ca), magnesium (Mg), and phosphorus (P) with menarcheal age were also examined.

Methods

This prospective study was conducted on 134 pre-pubertal girls, aged 4-12 years at baseline, who participated in the Tehran Lipid and Glucose Study (TLGS), and were followed for a median of 6.5 years. Dietary intakes were determined at initiation of the study using two non-consecutive 24-h dietary recalls and the age of menarche was documented during the follow-up. Logistic regression was used to calculate the risk of reaching menarche ≤ 12 years according to pre-pubertal levels of dairy or mineral intakes.

Results

The risk of earlier menarche was higher in girls with higher intakes of milk [OR: 2.28 (95% CI: 1.03–5.05)], Ca [OR: 3.20 (95%CI: 1.39–7.42)], Mg [OR: 2.43 (95% CI: 1.12–5.27)] and P [OR: 3.37 (95 % CI: 1.44–7.87) after controlling for energy and protein intake, interval between the age at study initiation and the age of menarche, and maternal age at menarche (Model 1). Girls in the middle tertile of cheese intakes had a lower risk of reaching menarche ≤ 12 years than those in the lowest tertile after controlling for covariates in model 1. These associations remained significant after further adjustment of BMI Z-score at baseline. The relationship of Ca, Mg, and P with menarche remained after further adjustment for height Z-score at baseline, whereas the association between milk and cheese intakes became non-significant.

Conclusions

Pre-pubertal intake of milk, but not cheese and yogurt, may hasten age at menarche.     

Association between parathyroid hormone (PTH)/PTH-related peptide receptor gene polymorphism and the extent of bone mass reduction in primary hyperparathyroidism.

Genetic contributions to bone mineral density (BMD) and bone turnover are well known. In the present study, we analyzed the relationship between polymorphism of parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor gene existing in exon M7 and the clinical characteristics of primary hyperparathyroidism (pHPT). PTH/PTHrP receptor genotypes were analyzed in 92 pHPT patients by direct sequence to determine whether nucleotide 1417 of the cDNA was C or T. BMD levels at the lumbar spine and at the radius before and one year after parathyroidectomy, as well as serum levels of calcium, phosphorus, alkaline phosphatase (ALP) and intact PTH were measured. Although there were no significant differences in serum levels of calcium, phosphorus and intact PTH, ALP was significantly lower in the CT genotype compared with the TT genotype. BMD level at the radius was significantly higher in the CT genotype than in the CC genotype. Moreover, an increase in radial BMD one year after parathyroidectomy was significantly less in CT genotype than two other genotypes (CC, TT). The present study is the first to indicate that the polymorphism of PTH/PTHrP receptor gene is closely related to the extent of bone mass reduction in pHPT and that this polymorphism would be one of the genetic factors responsible for the severity of the pathological state of pHPT.     

Critical ages and stages of puberty in the accumulation of spinal and femoral bone mass: the validity of bone mass measurements

In growing children, lumbar and femoral areal bone mineral density (aBMD), as measured by dual-energy X-ray absorptiometry (DXA), is influenced by skeletal growth and bone size. Correction of lumbar bone mineral density (BMD) for bone volume (volumetric BMD [vBMD]), by the use of mathematical extrapolations, reduces the confounding effect of bone size, but vBMD remains dependent on age and bone size during growth. Femoral (neck and mid-shaft) vBMD, assessed by DXA, is independent of age prior to puberty, but a slight increase occurs in late puberty and after menarche. Femoral (mid-shaft) cortical bone density and radial cortical and trabecular bone densities, assessed by quantitative computed tomography (QCT), show no peak during childhood or adolescence. Bone strength index, calculated by peripheral QCT, increases with age and correlates with handgrip strength, bone cross-sectional area and cortical area. Puberty is one of the main factors that influences lumbar bone mineral content and aBMD accumulation, but a high incidence of fractures occurs during this period of life, which may be associated with a reduced aBMD.     

Effect of parathyroidectomy on bone mineral density in hemodialysis patients with secondary hyperparathyroidism: possible usefulness of preoperative determination of parathyroid hormone level for prediction of bone regain.

PURPOSE: To examine longitudinal changes of bone mineral density (BMD) after parathyroidectomy (PTx) in patients undergoing maintenance hemodialysis (HD) with severe secondary hyperparathyroidism (HPT) to determine which factor contributes most to bone changes. METHODS: Fifteen Japanese HD patients who had been refractory to medical therapy were subject to PTx with autotransplantation. We measured BMD by dual energy X-ray absorptiometry (DXA) at the lumbar spine (L2 - 4 BMD) and the distal 1/3 region of the radius (1/3R BMD) at 1, 3, 6, 12, 24, and 36 months after PTx. RESULTS: Baseline Z-score of BMD was markedly low at 1/3R (- 3.07) and slightly low at L2 - 4 (-0.59) in this group. A significant increase in L2 - 4 BMD was observed as early as one month after PTx, which was sustained afterwards. Annual percent changes in L2 - 4 and 1/3R BMD were + 15.6 % and + 6.4 %, respectively. The annual percent changes in BMD at both sites were positively associated with preoperative intact PTH levels (L2 - 4; r = 0.642, p = 0.010, 1/3R; r = 0.884, p < 0.001) and total alkaline phosphatase (ALP) levels (L2 - 4; r = 0.663, p = 0.007, 1/3R; r = 0.858, p < 0.001). Stepwise multiple regression analysis revealed that serum levels of intact PTH and ALP were the best predictors of both percentage and net changes in radial BMD with high determination coefficients (r 2 > 0.8). CONCLUSION: Successful PTx following appropriate supplementation with vitamin D and calcium provides a marked increase in lumbar BMD and a modest increase in radial BMD in HD patients with secondary HPT. Preoperative levels of PTH and ALP are useful for predicting postoperative changes in bone mass.     

Vitamin D Binding Protein Genotype Is Associated with Serum 25-Hydroxyvitamin D and PTH Concentrations,as Well as Bone Health in Children and Adolescents in Finland

Vitamin D binding protein (DBP)/group-specific component (Gc), correlates positively with serum vitamin D metabolites, and phenotype influences serum 25-hydroxyvitamin D (S-25(OH)D) concentration. The protein isoform has been associated with decreased bone mineral density (BMD) and increased fracture risk. We examined the role of GC genotypes in S-25(OH)D status and BMD in 231 Finnish children and adolescents aged 7−19 yr. BMD was measured with DXA from lumbar spine (LS), total hip, and whole body, and for 175 subjects, radial volumetric BMD was measured with pQCT. Background characteristic and total dietary intakes of vitamin D and calcium were collected. The concentrations of 25(OH)D, parathyroid hormone (PTH), calcium and other markers of calcium homeostasis were determined from blood and urine. Genotyping was based on single-nucleotide polymorphism (rs4588) in the GC gene. The genotype distribution was: GC 1/1 68%, GC 1/2 26% and GC 2/2 6%. A significant difference emerged in 25(OH)D and PTH concentrations between the genotypes, (p = 0.001 and 0.028 respectively, ANCOVA). There was also a linear trend in: Gc 2/2 had the lowest 25(OH)D and PTH concentrations (p = 0.025 and 0.012, respectively). Total hip bone mineral content was associated with GC genotype (BMC) (p = 0.05, ANCOVA) in boys. In regression analysis, after adjusting for relevant covariates, GC genotype was associated with LS BMC and strength and strain index (SSI) Z-score in both genders, and LS BMD in boys. In conclusion, the present study demonstrates the association between GC genotypes and S-25(OH)D and PTH concentrations. The results show the influence of DBP genetic variation on bone mass accrual in adolescence.     

Parathyroid hormone gene with bone phenotypes in Chinese

Osteoporosis is a common disorder afflicting old people. The parathyroid hormone (PTH) gene is involved in bone remodeling and calcium homeostasis, and has been considered as an important candidate gene for osteoporosis. In this study, we simultaneously tested linkage and/or association of PTH gene with bone mineral density (BMD) and bone mineral content (BMC), two important risk factors for osteoporosis. A sample of 1263 subjects from 402 Chinese nuclear families was used. The families are composed of both parents and at least one healthy daughter aged from 20 to 45 years. All the subjects were genotyped at the polymorphic BstBI site inside the intron 2 of the PTH gene (a nucleotide substitution of G to A at the position +3244). BMD and BMC were measured at the lumbar spine and the hip region via dual-energy X-ray absorptiometry (DXA). Using QTDT (quantitative trait transmission disequilibrium test), we did not find significant results for association or linkage between the PTH gene and BMD or BMC variation at the spine or hip. Our data do not support the PTH gene as a quantitative trait locus (QTL) underlying the bone phenotypic variation in the Chinese population.     

睾酮对去睾丸家兔骨密度及血清钙磷的影响

目的:观察去睾丸和睾酮补充对雄兔骨密度和血清钙、镁、磷的影响.方法:周龄相同的雄性新西兰白兔随机分成对照组、去睾丸组和睾酮补充组(去睾丸后肌注十一酸睾酮).同等条件下饲养20周后测量各组兔全身骨密度、腰椎骨密度、股骨颈骨密度,并检测血清总睾酮(TT)、雌二醇(E2),脱氢表雄酮(DHEA)水平以及血清钙(Ca2 )、游离钙([Ca2 ]i)镁(Mg2 )、磷(P)和碱性磷酸酶(AKP)浓度.结果:去睾丸组血清TT水平明显下降(P<0.01),睾酮补充组血清TT水平升高接近对照组(P>0.05).去睾丸组血清E2和E2/TT比明显高于对照组(P<0.01),睾酮补充组血清E2和E2/TT下降,接近对照组水平(P均>0.05).与对照组相比,去睾丸组血清Ca2 、[Ca2 ]i、Mg2 以及AKP浓度明显升高(P均<0.01),睾酮补充组血清Ca2 、[Ca2 ]i、Mg2 以及AKP浓度较去睾丸组低,接近对照组水平(P>0.05).股骨颈骨密度在去睾丸组明显低于对照组和睾酮补充组(P<0.01),而后两组无差别(P>0.05).结论:去睾丸后雄兔血清TT明显下降,E2和E2/TT比以及Ca2 、[Ca2 ]i、Mg2 和AKP浓度明显升高,骨密度显著下降,睾酮补充使上述异常明显改善.     

Bone metabolism in patients with primary hyperparathyroidism before and after surgery

Primary hyperparathyroidism (PHPT) is accompanied with a reduced bone mineral density (BMD) and an increased risk of fracture. Surgery is the only option for cure. It is hypothesized that in patients with PHPT bone metabolism normalizes after parathyroidectomy (PTX) and that BMD gradually increases. Fifty-two patients with PHPT who underwent surgery were prospectively followed for 1 year. Biochemical analyses were performed at baseline and 1, 4, 7 days; 6 weeks; and 3, 6, and 12 months, and BMD before and one year after surgery. Parathyroid hormone (PTH), calcium, and the bone resorption marker dropped immediately, but transiently after PTX, bone formation decreased more slowly. Osteoprotegerin (OPG) as well as cathepsin K did not show significant changes. BMD of the lumbar spine, but not of the femoral neck, increased significantly within one year after surgery. Moderate correlations existed between the changes of total calcium, ionized calcium, as well as bone-specific alkaline phosphatase and changes of the lumbar BMD. Patients who needed postoperative supplementation with calcium and vitamin D had significantly higher PTH levels. Some gender-specific differences in patients with PHPT were observed. In patients with PHPT, males appear to be more severely affected than females. Within the first year after PTX, bone metabolism normalized, and BMD of the lumbar spine increased. Patients who needed a supplementation with calcium and vitamin D after PTX preoperatively had higher serum levels of PTH.     

Alendronate increases bone mineral density in patients with symptomatic primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is often associated with low bone mineral density (BMD). An open-labeled, prospective trial was conducted to determine whether alendronate (ALN), 10 mg daily, maintains or improves BMD in patients with advanced PHPT. All patients had symptomatic PHPT and met surgical guidelines however refused surgery. Nineteen patients was treated with alendronate for 2 years. The primary outcome index, BMD, was measured at the lumbar spine (LS) and femoral neck (FN) every 6 months by dual-energy x-ray absorptiometry. Serum calcium, phosphorous and PTH, and urinary calcium excretion were monitored every 3 months. Treatment with alendronate over 2 years was associated with a significant (5.3+/-0.4%; p<0.01) increase in LS BMD in comparison with baseline. FN BMD increased significantly at 24 months with alendronate by 2.5%+/-0.7 (p<0.01) from baseline. Serum calcium, phosphorus and PTH, and urine calcium excretion did not change with alendronate therapy. In PHPT, alendronate significantly increases BMD at the LS and FN at 24 months from baseline values with stable serum calcium and PTH levels. Alendronate may be a useful alternative to parathyroidectomy in symptomatic PHPT among those with low BMD, who are candidates for surgery but either decline or for whom surgery is contraindicated.     

Serum BAP as the clinically useful marker for predicting BMD reduction in diabetic hemodialysis patients with low PTH

With decrease of serum PTH in hemodialysis (HD) patients, other factors besides parathyroid hormone (PTH) become important in regulating bone metabolism. We investigated which serum bone metabolic marker is the best to predict the bone mineral density (BMD) reduction in HD patients with serum PTH<180 pg/ml. The bone formation markers, bone alkaline phosphatase (BAP), intact osteocalcin (OC), and N-terminal propeptide of type I collagen (PINP), and the bone resorption markers, deoxypyridinoline (DPD), pyridinoline (PYD), and beta-crossLaps (beta-CTx) were measured in serum from 137 HD patients. BMD of all patients was measured twice, approximately 1.5 years before and 1.5 years after measurement of their markers of bone metabolism. In all 137 HD patients, serum BAP was the only marker significantly higher in those with BMD reduction than in those without. In 42 diabetes mellitus (DM) HD patients with serum PTH<180 pg/ml, hypothetically low bone turnover state, serum BAP was again the only marker to discriminate those with BMD reduction from those without. At serum PTH<60 pg/ml, serum BAP retained tendency toward higher value. These findings suggest that serum BAP might be the most sensitive to identify small changes of bone metabolism in low bone turnover state. Retrospective study confirmed the usefulness of serum BAP in clinical practice by significantly higher values in those with bone loss at PTH<180 pg/ml even in under routine sample handling. In conclusion, serum BAP is a clinically useful bone formation marker to predict the BMD reduction in DM HD patients with low level of PTH.     

Effects of physical training on bone mineral density and bone metabolism

The purpose of this study was to examine the influences of long-term walking training and walking and jumping training on bone mineral density (BMD) and bone metabolism. Data from 28 healthy premenopausal women was assessed. The subjects were divided into the walking group (WG; 17 women mean+/-SE age 35+/-2 years), and the walking and jumping group (WJG; 11 women mean+/-SE age 39+/-1 years). BMD was measured in the lumbar spine and proximal femur using dual energy X-ray absorptiometry (DXA). As markers of bone metabolism, this study was to measure bone formation markers, bone-alkaline phosphatase (B-ALP: measured by enzyme immunoassay/EIA) and osteocalcin (BGP: by radioimmunoassay/RI) as well as bone resorption markers, parathyroid hormone (PTH: measured by/RI) and type I collagen cross-linked N-telopeptides (NTx: by EIA). Despite the significant decrease in body weight (p<0.05), no corresponding decrease in BMD was observed. Moreover, no significant difference in bone markers BGP, PTH, and NTx was observed. B-ALP was significantly increased (p<0.05) after one year, and the rate of this increase was greater in the WJG than in the WG. It is thus concluded that walking training for one year is beneficial for the promotion of bone formation, and that jumping stimulus maintain BMD effectively.     

Calcium supplementation increases bone mass in GH-deficient prepubertal children during GH replacement

BACKGROUND/AIMS: Since GH plays an important role in bone mineralization, and several studies demonstrated the positive influence of a higher calcium intake on bone mass, we studied the effect of calcium supplementation in GHD children during GH therapy. METHODS: 28 prepubertal GHD children, 5.0-9.9 years old, were assigned to two groups: group A (n = 14; 7 females) treated with GH, and group B (n = 14; 7 females) treated with GH + calcium gluconolactate and carbonate (1 g calcium/day per os). Auxological parameters, total bone mineral content (TBMC) and density (TBMD), leg BMC and BMD, lumbar BMD, fat mass (FM) and lean tissue mass (LTM), blood 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), osteocalcin (OC) and urinary N-terminal telopeptide of type I collagen (NTx) were determined at the start of therapy and after 1 and 2 years of treatment. RESULTS: During the 2 years of the study, TBMC, TBMD, leg BMC and BMD (but not lumbar BMD) increased in both groups of patients, however after 2 years of treatment they were significantly higher in the calcium-supplemented group B than in group A (p < 0.05, for all parameters). At the start of therapy, in both groups of patients percentage FM was higher and total and leg LTM lower than in controls (p < 0.05 for each parameter). Thereafter, FM decreased and LTM increased and after 2 years they were both different from baseline (p < 0.05). After 2 years of treatment, leg BMC and BMD were more positively correlated with regional leg LTM in patients of group B (r = 0.834 and r = 0.827, respectively; p < 0.001) than in patients of group A (r = 0.617 and r = 0.637, respectively; p < 0.05). 25-OHD and PTH levels were in the normal range in all patients at the start and during treatment. OC levels were lower and urinary NTx levels higher in patients than in controls (p < 0.05 for both parameters), either at the start and after 1 year of treatment. After 2 years of treatment, OC levels were significantly higher than at the start of the study (p < 0.05) in both groups of patients, but they were higher in group B than in group A (p < 0.05); on the contrary, urinary Ntx levels were lower in group B than in group A (p < 0.05). CONCLUSION: In GHD children, treated with GH, calcium supplementation improved bone mass; it may aid in reaching better peak bone mass and in protecting weight-bearing bones, usually completed in childhood to maximum levels, from risk of osteoporosis and fractures later in life.     

Vitamin D is a major determinant of bone mineral density at school age

Background

Vitamin D insufficiency in children may have long-term skeletal consequences as vitamin D affects calcium absorption, bone mineralization and bone mass attainment.

Methodology/Principal Findings

This school-based study investigated vitamin D status and its association with vitamin D intake and bone health in 195 Finnish children and adolescents (age range 7–19 years). Clinical characteristics, physical activity and dietary vitamin D intake were evaluated. Blood and urine samples were collected for serum 25-hydroxyvitamin D (25-OHD) and other parameters of calcium homeostasis. Bone mineral density (BMD) and body composition were measured with dual-energy X-ray absorptiometry (DXA). Altogether 71% of the subjects were vitamin D insufficient (25-OHD <50 nmol/L). The median 25-OHD was 41 nmol/L for girls and 45 nmol/L for boys, and the respective median vitamin D intakes 9.1 µg/day and 10 µg/day. In regression analysis, after adjusting for relevant factors, 25-OHD concentration explained 5.6% of the variance in lumbar BMD; 25-OHD and exercise together explained 7.6% of the variance in total hip BMD and 17% of the variance in whole body BMD. S-25-OHD was an independent determinant of lumbar spine and whole body BMD and in magnitude surpassed the effects of physical activity.

Conclusions/Significance

Vitamin D insufficiency was common even when vitamin D intake exceeded the recommended daily intake. Vitamin D status was a key determinant of BMD. The findings suggest urgent need to increase vitamin D intake to optimize bone health in children.     

The effect of dehydroepiandrosterone administration on intestinal calcium absorption in ovariectomized female rats

[Purpose] Dehydroepiandrosterone (DHEA) administration reportedly recovers osteoporosis, a bone disorder associated with bone deficiency in postmenopausal women. However, the physiological mechanism of DHEA in osteoporosis remains elusive, especially in terms of intestinal calcium absorption. Therefore, we investigated the effect of DHEA administration on calcium absorption in ovariectomized (OVX) female rats using an estrogen receptor antagonist.[Methods] Female Sprague-Dawley rats (n=23, 6 weeks old) were randomized into three groups: OVX control group (OC, n=7), OVX with DHEA treatment group (OD, n=8), and OVX with DHEA inhibitor group (ODI, n=8) for 8 weeks.[Results] Intestinal calcium accumulation, as well as the rate of absorption, demonstrated no significant differences during the experimental period among investigated groups. The bone mineral density (BMD) of the tibia at the proximal metaphysis was higher in the OD group than that in the OC group (p<0.05); however, BMD of the ODI group showed no significant difference from investigated groups. Furthermore, the BMD of the tibia at the diaphysis did not significantly differ among these groups.[Conclusion] We revealed that DHEA administration does not involve intestinal Ca absorption, although this treatment improves BMD levels in OVX rats. These observations indicate that the effect of DHEA on the bone in postmenopausal women is solely due to its influence on bone metabolism and not intestinal calcium absorption.