Sex differences in peak adult bone mineral density

Osteoporotic fractures are more common in women than men. Although accelerated bone loss following the menopause is recognized as of major importance, it is generally considered that a lower peak adult bone mass in females also contributes to their increased risk of osteoporosis in later life. To examine potential sex differences in peak adult bone mass we studied 29 pairs of dizygotic twins of differing within-pair sex in whom the female twin was premenopausal (mean age 37 years, range 21-55). Bone mineral density (BMD, g/cm2) was measured at the lumbar spine and femoral neck by dual-photon absorptiometry; 22 pairs also had BMD measured in the distal and 21 pairs in the ultradistal radius by single-photon absorptiometry. There was no significant difference in usual dietary calcium intake or tobacco consumption between the twin pairs. Consistent with accepted dogma, BMD at both radial sites were higher (+27%) in the males than their female cotwins. In contrast, there was no sex difference (male versus female) in BMD (mean +/- SEM) in the femoral neck (0.96 +/- 0.02 versus 0.97 +/- 0.03), and surprisingly, the females had a greater lumbar spine BMD than their male cotwins (1.19 +/- 0.03 versus 1.26 +/- 0.03, p less than 0.05). This difference was observed despite the fact that the males were taller (p = 0.033). If the femoral neck BMD values in the females were corrected for this difference in BMI, their values (0.99 +/- 0.03 g/cm2) were significantly higher than those in their male cotwin (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lumbar spine bone mineral density at diagnosis and during follow-up in children with IBD.

Lumbar spine body mineral density (BMD) was measured in 123 children (65 male, 58 female) suffering from inflammatory bowel disease (IBD) (82 Crohn's disease, 41 ulcerative colitis) and in 46 children (25 male, 21 female) without any history of bone disease. Results in normal children showed that densitometer-derived reference values overestimated spine BMD, particularly for young children, such that the reported mean Z-scores for normal 10-yr-old children were -0.83 for males and -0.72 for females. For children with Crohn's disease, the lumbar spine BMD was further reduced (Z-score = -1.44 for males, Z-score = -1.37 for females). For children with ulcerative colitis, the lumbar spine BMD was similar to that of normal children (Z-score = -0.93 for males, Z-score = -0.56 for females). There was no statistically significant reduction in average spine BMD Z-scores during follow-up periods ranging from 1.7 to 8.7 yr. When growth patterns were examined in individual children, six patients (three Crohn's disease, three ulcerative colitis) were identified as losing spine BMD with respect to their baseline value and their expected pattern of BMD increase associated with normal growth. The children suffering from IBD who, most likely, will not maintain expected growth-related increases in spine BMD are those who are male, relatively young at diagnosis, and unlikely to be taking immunosuppressants.     

Evaluation of salivary parameters and dental status in adult hemodialysis patients

AIMS: Caries is a multifactor disease, and impaired stimulated salivary flow rate and buffering capacity are the best-known risk factors. The salivary flow rate, pH, buffering capacity and DMFT (decayed, missing and filled teeth) index of adult hemodialysis patients were compared with those of healthy controls. MATERIAL AND METHODS: Seventy-two (34 F, 38 M, mean age: 45.05 +/- 14.15 years) hemodialysis patients and 50 (26 F, 24 M, mean age: 43.92 +/- 18.80 years) control saliva were collected after prestimulation and expressed as ml/min. Salivary pH and buffering capacity were measured (Ericsson method). The dental examinations were performed according to WHO criteria and DMFT index was calculated. Statistical analysis was performed with Student t-test and Pearson correlation test. RESULTS: The patients' mean salivary flow rate was 0.69 +/- 0.31 ml/min, pH, 8.15 +/- 0.72, buffering capacity, 6.83 +/- 0.71 and DMFT index was 11.91 +/- 8.73. The salivary flow rate was less than the controls (p <0.001), but salivary pH and buffering capacity were higher (both p < 0.001). There was no difference in DMFT index between groups (p > 0.05). There was no significantly negative correlation between DMFT index and stimulated salivary flow rate, pH but there was a positive correlation with buffering capacity (r = 0.286, p < 0.05) in the patients. Moreover, there was no significantly positive correlation between stimulated salivary flow rate and pH buffering capacity in these patients. CONCLUSIONS: Salivary flow rate of hemodialysis patients was less than the hyposalivary limit. Salivary pH and buffering capacity were both above the reference values, but DMFT index of hemodialysis patients did not differ from that of controls. However, caries and related dental infections may lead to serious problems in infection-prone hemodialysis patients, so these patients should have regular dental examinations and careful treatments.     

Males have larger skeletal size and bone mass than females, despite comparable body size.

Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in 18-year-old males (n = 36) and females (n = 36) matched for height and weight. Despite comparable body size, males have greater BMC and BMD at the hip and distal tibia and greater tibial cortical thickness. This may confer greater skeletal integrity in males. INTRODUCTION: Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in males (n = 36) and females (n = 36; mean age = 18 years) pair-matched for height and weight. MATERIALS AND METHODS: BMC, bone area (BA), and BMD were measured in the spine and hip using DXA. Distal tibia was measured by pQCT. RESULTS AND CONCLUSIONS: Males had a higher lean mass (92%) compared with females (79%). No gender differences were observed for vertebral BMC or vertebral height, although males had greater width and thus BA at the spine. Males had greater BMC and BA at the femoral neck and total femur (p < 0.02). Geometric variables of the hip including neck diameter and neck-axis length were also greater in males (p < 0.02). There was greater cross-sectional moment of inertia, safety factor, and fall index in males (all p < 0.02). Males had greater tibial BMC, volumetric BMD, and cortical area and thickness compared with females (p < 0.01), with both greater periosteal circumference (p = 0.011) and smaller endosteal circumference (p = 0.058). Statistically controlling for lean mass reduced gender differences, but males still had 8% higher hip BMD (p = 0.24) and 5.3% higher total tibial BMD (p = 0.05). A subset of males and females were matched (n = 14 pairs) for total hip BA. Males in this subset still had greater BMC and BMD at the total hip (p < 0.05) than females, despite similar BA. In summary, despite comparable body size, males have greater BMC and BMD than females at the hip and distal tibia but not at the spine. Differences in BMC and BMD were related to greater cortical thickness in the tibia. We conclude that differences in bone mass and geometry confer greater skeletal integrity in males, which may contribute to the lower incidence of stress and osteoporotic fractures in males.     

Comparison of the humoral markers of bone turnover and bone mineral density in patients on haemodialysis and continuous ambulatory peritoneal dialysis

Renal osteodystrophy is an important complication in patients with end-stage renal disease on maintenance dialysis. The aim of this study was to compare the biochemical markers of bone formation (serum collagen type I C-terminal propeptide) and resorption (serum deoxypyridinoline - DPD - and pyridinoline - PYR) with the bone mineral density (BMD) at lumbar spine, femoral neck, and forearm in patients with end-stage renal disease on haemodialysis (HD) versus continuous ambulatory peritoneal dialysis (CAPD). Fifty-nine adult patients, 45 on CAPD (18 females, 27 males) and 14 on HD (2 females, 12 males), were studied. The mean age was 44 +/- SEM 1.6 and 54.4 +/- 4.8 years, respectively. No significant differences in serum calcium, phosphorus, creatinine, and parathyroid hormone were found between patients on HD and CAPD in predialysis samples. Serum urea was significantly lower (p = 0.02) in the CAPD group. Serum PYR (nmol/l) and DPD (nmol/l) were significantly higher in patients on HD as compared with those on CAPD: 105 +/- 23.3 versus 43.7 +/- 3.47 (p = 0.007) and 31.0 +/- 2.4 versus 24.4 +/- 1.4 (p = 0.027), respectively. The results were still significantly higher in the HD patients following correction for serum creatinine and body mass index. There was a close correlation between dialysate DPD and creatinine in both dialysis modalities (HD r = 0.9, CAPD r = 0.76). The clearance of DPD did not differ significantly between the CAPD membrane and the HD membrane (p = 0.22). Serum collagen type I C-terminal propeptide was not significantly different between the HD and CAPD patients. The results were unaffected following correction for age and gender. The BMD was measured in 38 (65%) of the patients (HD n = 8, CAPD n = 30) by dual-energy X-ray absorptiometry and expressed as 'Z' scores. This was reduced at all sites in the patients with end-stage renal disease. The BMD was significantly lower at the ultradistal forearm (mostly trabecular bone) in HD patients as compared with CAPD patients (n = 0.02). A similar trend was observed at the lumbar spine, although the results failed to reach significance. In the whole population (n = 38), linear regression analysis revealed a significant negative correlation between BMD at the ultradistal forearm and serum PYR (r = -0.35, p = 0.04) and DPD (r = -0.33, p = 0.049). Combined measurements of BMD and biochemical markers of bone resorption may have potential in the identification of patients at high risk of bone loss who may require further evaluation of bone remodeling by bone histomorphometry.     

High bone mass in a female Hutterite population.

We examined a Hutterite population (n = 243) to determine if their agriculturally diverse, self-sufficient communal lifestyle promotes optimal bone mass attainment because of adequate calcium intake and high physical activity levels during growth and young adulthood. We measured total body (TB) and lumbar bone mineral content (BMC) and bone mineral density (BMD) in 39 school-age (younger) females and 204 working (older) females. Forty-five percent of older females and 79% of younger females currently consumed > or = 3 servings (svg) of dairy per day. Older females had lumbar (0.6 +/- 1.3) and TB (1.1 +/- 1.1) BMD Z scores greater than 0 (both, p < 0.001). The lumbar BMD Z score of younger females was not different from 0 (-0.1 +/- 1.0; p = 0.5). Both lumbar (r = 0.46; p < 0.001) and TB (r = 0.20; p = 0.02) BMD Z scores increased with increasing age. In multiple regression analyses for older females, lumbar bone area (p < 0.001), weight (p < 0.001), current hours on feet per day (p = 0.01), colony workload (p < 0.01), and estrogen status (p = 0.06) predicted lumbar BMC. TB bone area (p < 0.001), current hours on feet per day (p < 0.001), and colony workload (p < 0.01) predicted TB BMC. For younger females, lumbar bone area (p < 0.001), weight (p < 0.01), years in present colony (p = 0.02), and menses (p < 0.001) predicted lumbar BMC. TB bone area (p < 0.001), height (p < 0.01), years in present colony (p = 0.03), and menses (p < 0.01) predicted TB BMC. The effect of colony workload could not be separated from other factors different by colony. A heritability estimate of 0.66 was calculated for lumbar BMD using mother and daughter Z scores. Adequate calcium intake during growth, high physical activity early in life, and genetic factors may be contributing to above normal BMD levels in adult female Hutterites.     

Quantification of bone mineral content using dual-photon absorptiometry in a normal Japanese population

The bone mineral content of lumbar spine and/or total body were quantified in 217 healthy Japanese (86 males and 131 females) using a Dichromatic Bone Densitometer (Norland Corp., Model 2600). The bone mineral density of the third lumbar vertebra (L3 BMD) decreased significantly after age 20 in males (r = -0.417, p less than 0.0002), with acceleration of the decrease after age 50 (r = -0.621, p less than 0.00002). A significant correlation was found between L3 BMD and age after age 40 (r = -0.747, p less than 0.0001) in females. L3 BMD correlated with both the body height (r = 0.335, p less than 0.0001) and the body weight (r = 0.340, p less than 0.0001). Total bone mineral content from the second to fourth lumbar vertebrae correlated significantly with total body bone mineral (r = 0.880, p less than 0.00001) in these normal subjects. Lumbar spine bone mineral as measured by dual-photon absorptiometry is lower in Japan than the bone mass in the United States, although not lower than in other parts of the world.     

Simulated change in body fatness affects Hologic QDR 4500A whole body and central DXA bone measures.

Changes in body fatness may impact the accuracy of dual energy X-ray absorptiometry (DXA) measures of bone mineral content (BMC) and bone mineral density (BMD). The aim of this study was to determine if DXA can accurately assess BMC and BMD with changes in exogenous fat (lard) placed to simulate weight change. Whole body (WB), lumbar spine (LS), and proximal femur (PF) DXA scans (Hologic QDR 4500A) were performed on 30 elderly (52-83 yr) and 60 young (18-40 yr) individuals (i.e., 45 females and 45 males) of varying body mass index (mean+/-standard deviation: 26.1+/-4.9 kg/m2). When scans were repeated with lard packets (2.54 cm thick, 25.4x17.8 cm, 1 kg), WB BMD decreased 1.1% and 1.6% after chest and thigh packet placement, respectively (p=0.001), PF BMD increased 0.7% (p=0.02) and LS BMD decreased 1.6% (p=0.001) primarily due to a 2.2% reduction in LS BMC (p<0.001). Initial LS BMC and trunk mass were related to error in LS BMC measures due to lard-loading (r=0.64 and 0.45, respectively, p<0.001). We conclude that on average simulated weight change minimally impacts PF bone measures and moderately impacts WB and LS bone measures; however, individual variability in measurement error was noteworthy and may be impacted by body thickness.     

Use of quantitative ultrasound to assess bone status in children with juvenile idiopathic arthritis: a pilot study.

Periarticular osteoporosis around inflammed joints and generalized osteoporosis have been shown to be markers of disease activity and severity in children with juvenile idiopathic arthritis (JIA). Bone mineral density (BMD) in adults can be assessed precisely by dual X-ray absorptiometry (DXA), but this technique has not been used widely in children. Quantitative ultrasound (QUS) may provide an alternative method for assessment of bone status. The aim of this pilot study was to compare QUS to DXA in assessing generalized osteoporosis in a cohort of patients JIA. Twenty-two Caucasian children (15 females, 7 males) with JIA of duration 19-142 months (mean 71 mo) and age 7-17 yr were recruited. Total body and lumbar spine BMD and bone mineral content (BMC) were measured by DXA using standard procedures on a Lunar DPX-L scanner. QUS was performed using Myriad SoundScan 2000. Speed of sound (SOS) was measured at the right midtibia. The DXA results were compared to QUS using linear regression analysis. Spine and total body BMD measured by DXA correlated significantly with tibia SOS (spine: r = 0.57, p < 0.007; total body: r = 0.68, p < 0.001). Spine BMC was similarly related to SOS as BMD (r = 0.58, p < 0.007). Individual patient weight and height were strong predictors of BMD, but only moderate predictors of SOS. The mean spine BMD was lower in the JIA patients compared to the normal ranges (mean Z-score of -1.19). BMD Z-scores were negatively associated with disease duration. Patients taking steroids were associated with lower Z-scores. In conclusion, SOS shows a significant correlation with BMD as measured by DXA, albeit with wide 95% confidence intervals in this small pilot study. QUS was also well tolerated and was technically easy to perform in these children. With the added advantage that it is free from radiation risk, further assessment of this potentially valuable tool for measuring bone status in children is warranted.     

Interleukin-6 gene polymorphism is related to bone mineral density during and after puberty in healthy white males: a cross-sectional and longitudinal study.

Bone mineral density (BMD) is under strong genetic control and is the major determinant of fracture risk. The cytokine interleukin-6 (IL-6) is an important regulator of bone metabolism and is involved in mediating the effects of androgens and estrogens on bone. Recently, a G/C polymorphism in position -174 of the IL-6 gene promoter was found. We investigated this genetic polymorphism in relation to BMD during late puberty and to peak bone mass, in healthy white males. We identified the IL-6 genotypes (GG, GC, and CC) in 90 boys, age 16.9 +/- 0.3 years (mean +/- SD), using polymerase chain reaction (PCR). BMD (g/cm2) at the femoral neck, lumbar spine, and total body was measured using dual energy X-ray absorptiometry. The volumetric BMD (vBMD; mg/cm3) of the lumbar spine was estimated. Differences in BMD in relation to the genotypes were calculated using analysis of variance (ANOVA). Subjects with the CC genotype had 7.9% higher BMD of the femoral neck (p = 0.03), 7.0% higher BMD of the lumbar spine (p < 0.05), and 7.6% higher vBMD of the lumbar spine (p = 0.04), compared with their GG counterparts. Using multiple regression, the IL-6 genotypes were independently related to total body BMD (CC > GG; p = 0.03), humerus BMD (CC > GG; p < 0.05), neck BMD (CC > GG; p = 0.01), spine BMD (CC > GG; p = 0.01), and spine vBMD (CC > GG; p = 0.008). At age 19.3 +/- 0.7 years (mean +/- SD; 88 men) the IL-6 genotypes were still independent predictors for total body BMD (CC > GG; p = 0.03), humerus BMD (CC > GG; p = 0.03), spine BMD (CC > GG; p = 0.02), and spine vBMD (CC > GG; p = 0.003), while the IL-6 genotypes were not related to the increase in bone density seen after 2 years. We have shown that polymorphism of the IL-6 gene is an independent predictor of BMD during late puberty and of peak bone mass in healthy white men.     

瓦努阿图中学生恒牙龋病发病情况及相关因素分析

目的：了解瓦努阿图桑托岛居住的12岁及13～19岁中学生龋齿的患病情况,为在该地区制定中学生龋病的防治措施,提供基本资料。方法：将1821名该地区居住的中学生,在室外条件下检查恒牙的患龋情况,并记录DMFT值,用SPSS统计软件分析各年龄组之间以及各牙位之间的患龋情况。结果：12岁组的患病率为30.43%（男25.08%,女36.23%）,龋均为0.66（男0.54,女0.79）。13～19岁组的患龋率为49.92%（男44.39%,女55.79%）,龋均为1.56（男1.22,女1.92）。性别及各年龄组患龋率和龋均有显著性差异。患龋最多的为下颌磨牙,其次为上颌磨牙,发病率最低的是下颌乳尖牙,其次上颌乳尖牙。12岁组及13～19岁组恒牙龋齿的充填率分别为0.53%和3.92%。结论：瓦国桑托岛居住的中学生恒牙龋齿的患病率较低,可能与当地的饮食结构有关,但龋齿的充填率也很低,应当加大口腔保健的服务力度。     

Correlation between hand and total body bone density in normal Chinese children

Hand bone mineral density (BMD) in adults was found to be significantly correlated with various skeletal sites, including the total body. However, the relationships between hand and total body bone measurements have yet to be explored for children. We conducted a cross-sectional study of 892 normal Chinese children (511 males, 381 females) aged 5-14 years by measuring the BMD and bone mineral content (BMC) at the total hand, upper limb, subtotal body, and total body using dual-energy X-ray absorptiometry (DXA). We found that hand BMD and BMC increased with age for both genders. Female children had significantly higher hand BMD and BMC than males. Age explained more variance in hand BMD for females (R2=0.727) than for males (R2=0.596). For both genders, hand BMD and BMC correlated highly with age, weight, height, total body lean mass, and BMD and BMC at the upper limb, subtotal body, and total body (r=0.730-0.965, p<0.001) and moderately with body mass index and total body fat mass (r=0.525-0.701, p<0.001). Therefore, the hand DXA scan can potentially be a new tool for the clinical assessment of bone health in children.     

Uncoupling of Bone Turnover may Compromise Skeletal Health of Young Patients With Haemophilia A

There is evidence that bone mass is decreased and bone metabolism is dysregulated in children with haemophilia (CWH). The objective of this study was to investigate the impact of haemophilia on skeletal health in children, with regards to bone mineral density (BMD) and metabolic bone profile. This study included 51 male CWH A. Dual-energy X-ray absorptiometry (DXA) was performed to assess BMD in lumbar spine (LS) and total body less head (TBLH) and Z-scores were calculated (low BMD Z-score<-2, low-normal BMD Z-score between -1 and -2). Serum levels of osteocalcin (OC), procollagen type I C-terminal propeptide (PICP), bone alkaline phosphatase (bALP), bone tartrate-resistant acid phosphatase 5b (TRAP5b), vitamin D, parathormone (PTH), urinary calcium/creatinine (uCa/uCr) and urine deoxypyridinoline/creatinine (uDPD/uCr) were measured. Mean BMD Z-scores were lower than predicted at both sites of measurement. More specifically, 10% of CWH A had low and 20% low-normal BMD Z-scores in LS, whereas 9.1% had low-normal TBLH BMD Z-scores and there were no patients with low BMD Z-scores at this site of measurement. 36.7% of CWH had low vitamin D levels and 19.6% had a history of fracture. Also, patients with haemophilia had lower OC and higher uDPD/uCr levels while OC positively correlated to BMD Z-scores and uDPD/uCr negatively correlated to BMD Z-scores at both sites. No statistically significant differences were observed with regards to mode of treatment, number of haemorrhages and the presence of target-joints. CWH A had decreased BMD Z-scores at both sites with an uncoupling of bone turnover LS BMD seemed to be more affected than TBLH BMD.     

Peptide YY (PYY) levels and bone mineral density (BMD) in women with anorexia nervosa

INTRODUCTION: Anorexia nervosa (AN) is a psychiatric illness that results in significant bone loss. Studies examining the neuroendocrine dysregulation that occurs in AN may increase understanding of endocrine systems that regulate bone mass. Peptide YY (PYY) is an anorexigenic peptide derived primarily from the intestine, with actions mediated via activation of Y receptors. We have previously shown that PYY levels are elevated in adolescents with AN. Y2 receptor knockout mice have increased bone mineral density (BMD) and thus PYY may play a role in regulating bone mass. We hypothesized that PYY levels would be inversely associated with BMD in women with AN. METHODS: This was a cross-sectional study performed in a General Clinical Research Center of 12 adult women with AN, (mean+/-SEM) mean age 30.9+/-1.8 years, BMI 17.1+/-0.4 kg/m2, and % ideal body weight 77.5+/-1.7%. PYY concentrations were measured hourly from 20:00 h to 08:00 h. BMD was measured using dual X-ray absorptiometry (DXA). RESULTS: In women with AN, mean overnight PYY levels strongly inversely correlated with BMD at the PA spine (r=-0.77, p=0.003), lateral spine (r=-0.82, p=0.002), total hip (r=-0.75, p=0.005), femoral neck (r=-0.72, p=0.009), total radius (r=-0.72, p=0.009) and 1/3 distal radius (r=-0.81, p=0.002). Body mass index was inversely correlated with PYY level (r=-0.64, p=0.03). Multivariate stepwise regression analysis was performed to determine the contribution of age, duration of AN, BMI, fat-free mass, and PYY to BMD. For PA and lateral spine, PYY was the primary determinant of BMD, accounting for 59% and 67% of the variability, respectively. Fat-free mass and duration of anorexia nervosa were the primary determinants of BMD at other skeletal sites. CONCLUSIONS: In women with anorexia nervosa, an elevated PYY level is strongly associated with diminished BMD, particularly at the spine. Therefore further investigation of the hypothesis that PYY may contribute to the prevalent bone pathology in this disorder is merited.     

Comparison of bone parameters by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography in Hutterite vs. non-Hutterite women aged 35-60 years

A previous report of elevated dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) Z scores suggests that Hutterite females might be significantly less likely to develop osteoporosis compared with other U.S. females. In the present study, we sought to determine if high Hutterite DXA BMD Z scores were elevated because of larger bone size. Hutterites reside in isolated, self-sufficient colonies with an emphasis on agricultural production, and girls enter a strenuous task rotation at age 15 years. We obtained cross-sectional bone measurements of the 66% distal tibia using peripheral quantitative computed tomography (pQCT) to compare bone size and geometry on 97 Hutterite and 30 non-Hutterite women, aged 35-60 years. Total body (TB) and lumbar bone mineral content (BMC), BMD, and bone area measurements by DXA were available on a subset of the study population. We identified no differences between groups in pQCT total bone area, cortical bone area, or cortical bone density. Larger bone area by DXA was apparent in Hutterites compared with non-Hutterites at the TB (least square means: 2038 +/- 8 cm2 vs. 1953 +/- 19 cm2, p < 0.05) and lumbar (least square means: 58 +/- 0.5 cm2 vs. 57 +/- 2 cm2, p < 0.01) sites. TB BMC adjusted for TB bone area was marginally higher in Hutterites compared with non-Hutterites (least square means: 2341 +/- 15 g vs. 2281 +/- 30 g, p = 0.08). Hutterites had marginally higher TB BMD Z scores when controlling for weight and age (least square means: 1.3 +/- 0.1 vs. 0.8 +/- 0.2, p = 0.07). Hutterites had higher lumbar BMC adjusted for lumbar bone area and weight (least square means: 65 +/- 1 g vs. 58 +/- 2 g, p < 0.01) and higher weight-and age-adjusted lumbar BMD Z scores (least square means: 1.1 +/- 0.1 vs. 0.1 +/- 0.4, p = 0.01). Our data indicate that a true advantage in trabecular bone density probably exists among Hutterite women aged 35-60 years. Hutterite women might be protected against age-related fractures because of their larger bone size and higher bone density at normally susceptible trabecular sites.     

High sodium chloride intake is associated with low bone density in calcium stone-forming patients

BACKGROUND: Although renal stone disease has been associated with reduced bone mass, the impact of nutrient intake on bone loss is unknown. SUBJECTS AND METHODS: The present study was undertaken to investigate the influence of nutrient intake on bone density of 85 calcium stone-forming (CSF) patients (47 male and 38 premenopausal females) aged 41+/-11 years (X+/-SD). Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry at the lumbar spine (L2-L4) and femoral neck sites, and low BMD was defined as a T score < -1 (WHO criteria). A 4-day dietary record and a 24-hour urine sample were obtained from each patient for the assessment of nutrient intake and urinary calcium (U(Ca)), sodium (U(Na)), phosphate and creatinine excretion. RESULTS: Forty-eight patients (56%) presented normal BMD and 37 (44%) low BMD. There were no statistical differences regarding age, weight, height, body mass index, protein, calcium and phosphorus intakes between both groups. The mean U(Ca), phosphorus and nitrogen appearance also did not differ between groups. However, there was a higher percentage of hypercalciuria among low vs normal BMD patients (62 vs 33%, p < 0.05). Low BMD patients presented a higher mean sodium chloride (NaCl) intake and excretion (UNa) than normal BMD (14+/-5 vs 12+/-4 g/day and 246+/-85 vs 204+/-68 mEq/day, respectively p < 0.05). The percentage of patients presenting NaCl intake > or = 16 g/day was also higher among low vs normal BMD patients (35 vs 12%, p < 0.05). After adjustment for calcium and protein intakes, age, weight, body mass index, urinary calcium, citrate and uric acid excretion, and duration of stone disease, multiple-regression analysis showed that a high NaCl intake (> or = 16 g/day) was the single variable that was predictive of risk of low bone density in CSF patients (odds ratio = 3.8). CONCLUSION: These data suggest that reducing salt intake should be recommended for CSF patients presenting hypercalciuria and osteopenia.     

A Comparison of Calcaneus Ultrasound and Dual X-Ray Absorptiometry in Healthy North American Youths and Young Adults

Quantitative ultrasound is the newest noninvasive method to be accepted for assessing bone mineral in adults. Heel ultrasound measurements correlate with bone density measurements by dual X-ray absorptiometry (DXA) and predict fracture risk in adults. Far less is known about the value of calcaneus ultrasound (CUS) in children. We determine spine, femoral neck, and whole-body bone mineral by DXA and heel bone mass by CUS in 125 youths (69 females, 56 males) ages 9-25 yr. CUS and DXA measurements of bone mass increased with age and pubertal development during adolescence in a parallel fashion. Among females, Tanner stage was a stronger predictor than age for all CUS and DXA measurements, and among males, pubertal stage was a stronger predictor for spine bone mineral apparent density (BMAD) and femoral bone mineral density (BMD). CUS measurements correlated moderately well with DXA measurements of the spine, femoral neck, and whole-body BMD and spine BMAD (r = 0.23-0.58, p < 0. 008). CUS warrants further study as a tool for assessing bone mineral acquisition in children.     

Discordance in DXA male reference ranges.

Previous studies have reported discordance in female lumbar spine and proximal femur dual-energy X-ray absorptiometry (DXA) reference ranges. Although the NHANES III reference range is recommended for the proximal femur in males and females, there are no published data in men on the concordance or otherwise of the different manufacturer-specific lumbar spine bone mineral density (BMD) reference ranges. Potentially, the use of different reference populations by different manufacturers could result in inconsistencies in the diagnosis of osteopenia or osteoporosis. We compared lumbar spine BMD, as well as T-scores and Z-scores, in 45 men scanned using Lunar DPXL and Norland Excel densitometers. The BMD measured by the two instruments was highly correlated (lumbar spine: r = 0.99, p < 0.0001). However, the two instruments assigned significantly different BMD T-scores. These differences relate primarily to the different standard deviations employed in the calculations. There were also significant differences when BMD was expressed with respect to age-matched values (Z-scores). This study shows that in men, as previously demonstrated in women, two commonly used DXA instruments provide comparable lumbar spine standardized BMD, but there are significant differences in derived T-scores because of differences in the manufacturer-specific reference ranges. Standardization of lumbar spine reference ranges in men should be a high priority.     

Diabetes is associated independently of body composition with BMD and bone volume in older white and black men and women: The Health, Aging, and Body Composition Study.

The association between type 2 diabetes, BMD, and bone volume was examined to determine the effect of lean and fat mass and fasting insulin in the Health, Aging, and Body Composition Study, which included white and black well-functioning men and women 70-79 years of age (N = 2979). Diabetes predicted higher hip, whole body, and volumetric spine BMD, and lower spine bone volume, independent of body composition and fasting insulin. INTRODUCTION: The purpose of this study was to determine if the association between type 2 diabetes and higher BMD observed in older white women is seen in elderly white men and blacks and to evaluate if higher BMD in diabetic individuals is accounted for by lean mass, fat mass, or fasting insulin differences. MATERIALS AND METHODS: In the Health, Aging, and Body Composition Study, which included white and black well-functioning men and women 70-79 years of age (N = 2979), 19% of participants had diabetes at baseline. Of those with diabetes, 57% were men, and 62% were black. Multivariate linear regression models examined independent effects of diabetes, lean mass, fat mass, visceral fat, and fasting insulin on BMD and bone volume while adjusting for relevant covariates. RESULTS AND CONCLUSIONS: Fasting insulin, visceral fat, and volumetric spine BMD, assessed by CT, and lean mass, fat mass, and total hip and whole body BMD, assessed by DXA, were higher (p < or = 0.05 for all) for those with diabetes. Hip BMD was higher in white men (0.99 +/- 0.14 versus 0.93 +/- 0.14 g/cm2, p < 0.001), black men (1.06 +/- 0.17 versus 1.00 +/- 0.15 g/cm2, p < 0.001), white women (0.83 +/- 0.13 versus 0.76 +/- 0.13 g/cm2, p < 0.001), and black women (0.90 +/- 0.15 versus 0.85 +/- 0.15 g/cm2, p < 0.001) with diabetes compared with those without diabetes, although the relationship was attenuated by body composition. In multiple regression models, diabetes was an independent predictor of higher hip, whole body, and volumetric spine BMD in all participants (p < or = 0.001), but lower spine volume (p = 0.01) and higher hip BMD for each race-gender group (p < or = 0.01). Type 2 diabetes was associated with a 4-5% higher total hip BMD in all race-gender groups of elderly adults, independent of body composition and fasting insulin levels.