Whole-Body Bone Mineral Measurements in 15-Year-Old Swedish Adolescents

Bone mineral area (BA), total bone mineral content (TBMC) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 396 randomly selected, healthy 15-year-old Swedish boys and girls. The influence of body size, pubertal development, physical activity level (PAL), total energy expenditure (TEE), dietary intake of energy, calcium and vitamin D, and alcohol and smoking habits on TBMC and TBMD were examined in bi- and multivariate analyses. In bivariate analyses BA, TBMC and TBMD showed strong correlations with weight, height and TEE in both sexes. In boys but not in girls these bone variables were significantly correlated with dietary intakes of energy, calcium and vitamin D. No significant correlations were found between PAL and the three bone variables. In multivariate analyses with TBMC as dependent variable BA, height, weight and Tanner stages explained 88% and 87% of the variance in boys and girls respectively. In similar analyses with TBMD as dependent variable the corresponding figures were 50% and 54%. The major part of the variance in all these models was explained by BA, and only a few percent by all the other independent variables. No significant reduction was found when TEE or daily intakes of calcium or vitamin D were introduced into the models. These results illustrate the importance of including BA, weight and height as independent variables in regression models of TBMC to avoid spurious associations with other variables in the analyses. The results may also indicate that in normal Swedish adolescents environmental factors such as dietary intake of nutrients play a minor role as determinants of bone mineralization. High levels of physical activity and bone mineral measures possibly explain the lack of significant correlations between these variables and do not imply a lack of association. Received: 16 December 1997 / Accepted: 19 May 1998     

Bone Size and Bone Mass in 10-Year-Old Danish Children: Effect of Current Diet

Lifestyle factors, such as diet, are believed to be involved in modifying bone health, although the results remain controversial, particularly in children and adolescents. The objective of the study was to identify associations between dietary factors and whole body bone measurements in 10-year-old children. The study was a cross-sectional analysis of a random sample of 105 healthy Danish children, aged 10 years (9.97 ± 0.09). Whole body bone mineral content (BMC) and bone area (BA) were determined by dual-energy X-ray absorptiometry. The influence of diet (7 day food records) on BMC and BA were examined in bi- and multivariate analyses. The mean intakes of calcium, protein, phosphorus and sodium were 1226 mg, 78 g, 1523 mg and 3.3 g, respectively. In bivariate analyses, BMC and BA were strongly positively correlated with height (p<0.001) and weight (p<0.001), and with intakes of energy (p<0.005) and several nutrients. BMC was adjusted for size by including BA, height and weight in the multiple linear regression, and BA was adjusted for size by including height and weight in the multiple linear regression. In multivariate analyses, size-adjusted BMC was positively associated with calcium intake (p = 0.02). Size-adjusted BA was positively associated with dietary protein (p = 0.003), and negatively associated with intakes of sodium (p = 0.048) and phosphorus (p = 0.01). In conclusion, calcium intake was positively associated with bone mineralization. There was a positive association between protein and BA, while for phosphorus and sodium the association was negative. The findings suggest that in addition to calcium, the intake of other nutrients influences bone development in prepubertal children. Received: 31 December 1999 / Accepted: 23 June 2000     

Bone Mineral Density of 704 Amateur Sportsmen Involved in Different Physical Activities

The aim of the study was to analyze the relation between sports and bone mass. Seven hundred and four men with no history of chronic disease were questioned on their adolescent and adult sporting activities. Their total body (TB) and regional (head, spine, arms and legs) bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry. BMD measurements and ratios of regional BMD to TB BMD were compared using a multiple regression analysis. Probands (mean age 30 years) were engaged in 14 sports activities: rugby, soccer, other team sports, endurance running, fighting sports, bodybuilding, multiple weightbearing activities, swimming, swimming with flippers, biking, rowing, climbing, triathlon and multiple mixed activities. They stated that they were practising a physical activity at the amateur level: 7.1 h/week between the ages of 11 and 18 years and 9 h/week between age 18 years and the day of the interview (no significant difference between physical activities). Rowers and swimmers had low TB BMD (1.22 and 1.17 g/cm²) and low leg BMD (1.37 and 1.31 g/cm²). Participants in rugby, soccer, other team sports and fighting sports had a high TB BMD (1.27–1.35 g/cm²) and high leg BMD (1.41–1.5 g/cm²). For head BMD, there was no stastistical difference among the different groups. Constructed ratios pointed out the site-specific adaptation of the skeleton: soccer player and runners had a higher leg ratio; bodybuilders, fighters, climbers and swimmers had a higher arm ratio; rugby players had a higher spine ratio. Head ratio was higher in non-weightbearing sports (rowing, swimming) than in weightbearing sports (rugby, team sports, soccer, fighting sports and bodybuilding). Thus the BMD and ratio differences among the 14 disciplines seem to be site-specific and related to the supposedly high and unusual strains created at certain sites during sport training by muscle stress and gravitational forces. Head ratio is closely related to the type of practice; its value could predict whether sport participants have developed the maximal peak bone mass they could achieve. Received: November 1999 / Accepted: 12 September 2000     

Measurement of Bone Mineral Density in Mother–Daughter Pairs for Evaluating the Family Influence on Bone Mass Acquisition: A GRIO Survey

The relative influence of genetic and environmental determinants on bone mass is still unclear. Using an original multicentric mode of recruitment, based on absorptiometry current practice, the hypothesis of a familial predisposition to low bone mineral content was assessed. The study was based on dual-energy X-ray absorptiometry (DXA) measurements of lumbar and femoral neck bone mineral density (BMD), using daughters of women with a low BMD (case mothers). These BMD values were compared with those of control daughters of women with a normal BMD. Case mothers (n= 72) aged 54.3 ± 4.8 years were recruited on the basis of a questionnaire and a vertebral Z-score < – 2 SD. Their healthy daughters of more than 20 years (n= 77) aged 28.2 ± 4.9 years had their vertebral and femoral BMD Z-score determined. The control groups were composed of mothers aged 54.1 ± 4.7 years, paired by age ± 2 years to the case mothers, and of their daughters of more than 20 years old, aged 27.7 ± 5.8 years. For daughters, a significant difference was found between the mean vertebral Z-scores (–0.82 ± 1.08 for cases and 0.01 ± 1.14 for controls, p < 0.0001). The difference was in the same direction but was not statistically significant for mean femoral Z-scores (–0.58 ± 1.15 for cases and –0.22 ± 1.33 for controls, p <0.073). These findings confirm the hypothesis of a familial predisposition to low BMD. Received: 18 June 1997 / Accepted: 16 January 1998     

Association of Physical Activity and Calcium Intake with the Maintenance of Bone Mass in Premenopausal Women

Altogether 92 initially 25- to 30-year-old women of 132 original subjects participated in this 4-year follow-up study, which evaluated the influence of physical activity and calcium intake on the bone mineral content (BMC) of premenopausal women. The subjects were originally selected for a cross-sectional study according to their level of physical activity (high PA⁺ and low PA^–) and calcium intake (high Ca⁺ and low Ca^–), and the original groups were maintained in this follow-up study. The mean loss of BMC (95% CI) in the pooled data was 1.5% (0.7% to 2.4%) at the femoral neck, 0.6% (–0.8% to 1.9%) at the trochanter and 6.0% (4.5% to 7.4%) at the distal radius during the 4-year follow-up. According to repeated measures analyses of covariance neither physical activity nor physical fitness at baseline was associated with the rate of bone loss from the proximal femur. High calcium intake and the maintenance of body weight were both associated with a lower rate of bone loss from the proximal femur and distal radius. In addition, a long duration of breast feeding was associated with a higher rate of bone loss from the distal radius. Received: 1 June 2001 / Accepted: 29 August 2001     

Regular Physical Exercise and Bone Mineral Density: A Four-Year Controlled Randomized Trial in Middle-aged Men. The DNASCO Study

The aim of the study was to investigate the effects of regular aerobic exercise training on bone mineral density (BMD) in middle-aged men. A population based sample of 140 men (53–62 years) was randomly assigned into the exercise and reference groups. BMD and apparent volumetric BMD (BMD_vol) of the proximal femur and lumbar spine (dual-energy X-ray absorptiometry, DXA) and anthropomorphic measurements were performed at the randomization and 2 and up to 4 years later. The participation rate was 97% and 94% at the second and third BMD measurements, respectively. As another indication of excellent adherence and compliance, the cardiorespiratory fitness (aerobic threshold) increased by 13% in the exercise group. The 2% decrease in the reference group is regarded as an age-related change in cardiorespiratory fitness. Regardless of the group, there was no association between the increase in aerobic threshold and change in BMD. In the entire group, age-related bone loss was seen in the femoral neck BMD and BMD_vol (p<0.01). BMD and BMD_vol values increased with age in L2–L4 (p<0.004). An increased rate of bone loss at the femoral neck was observed in men with a low energy-adjusted calcium intake (p = 0.003). Men who increased their alcohol intake during the intervention showed a decrease in the rate of bone loss at the femoral neck (p = 0.040). A decrease in body height associated with decreased total femoral BMD (r= 0.19, p = 0.04) and the change in body height was a predictor of bone loss in the femoral neck (β= 0.201). Long-term regular aerobic physical activity in middle-aged men had no effect on the age-related loss of femoral BMD. On the other hand, possible structural alterations, which are also essential for the mechanical strength of bone, can not be detected by the DXA measurements used in this study. The increase seen in lumbar BMD reflects age-related changes in the spine, thus making it an unreliable site for BMD follow-up in men. Received: August 2000 / Accepted: November 2000     

Maintenance of Body Weight, Physical Activity and Calcium Intake Helps Preserve Bone Mass in Elderly Women

This prospective study focused on lifestyle factors and weight maintenance that may modulate the rate of bone loss at the weight-bearing proximal femur and non-weight-bearing distal radius in elderly women. Altogether 128 women of 134 subjects participated in this study with a mean follow-up time 3.9 years (range 2.9–5.3 years). The initially 60- to 65-year-old subjects were originally selected by their level of physical activity [high (PA⁺) and low (PA^–)] and calcium intake [high (Ca⁺) and low (Ca^–)], and the original groups were maintained in this study. Physical fitness and bone mineral content (BMC) decreased significantly at a similar rate in all four study groups without any statistically significant between-group difference. The mean change in the muscle strength of leg extensors was −3.3% (95% CI −5% to −1.5 %) at follow-up when including all individuals. The leg extension strength was still 9.2% (95% CI 2.7% to 16.1%) better in the PA⁺ groups compared with PA^– groups at follow-up. The mean change in the forearm flexion strength was −14% (95% CI −16.5% to −11.3%) at follow-up with no difference in the strength level between PA⁺ and PA^– groups. The mean change in the estimated oxygen uptake was −3.4% (95% CI −5.6% to −1.1%) at follow-up. The PA⁺ groups were still fitter, the between-group difference in the estimated oxygen uptake being 11.9% (95% CI 4.8% to 19.5%). The mean changes in BMC at follow-up were −2.1% (95% CI −3.0% to −1.2%) at the femoral neck, −1.9% (95% CI −3.2% to −0.5%) at the trochanter, and −12.4% (95% CI −15.4% to −9.4%) at the distal radius, indicating mean annual losses of 0.6% (95% CI 0.3% to 0.8%), 0.5% (95% CI 0.1% to 0.8%), and 3.2% (95% CI 2.4% to 4.0%), respectively. Decreased body weight was associated with higher bone loss in all measured bone sites. High calcium intake and better preservation of physical fitness were associated with a smaller decrease in femoral neck BMC. Received: 25 July 2000 / Accepted: 1 December 2000     

Decreased Bone Mineral Density in Neurofibromatosis-1 Patients with Spinal Deformities

A cross-sectional study was carried out to obtain data on the bone mineral density status of a group of neurofibromatosis-1 patients with spinal deformities, and to search for possible accompanying changes in the bone mineral turnover. Neurofibromatosis-1 is a heredofamiliar disorder that is associated with a variety of skeletal anomalies (mostly spinal deformities) in 10–50% of patients. Intraoperatively, a poor vertebral bone quality has been observed. Efforts have been made to identify factors preventing curve progression, to optimize operational planning and to explain the pathomechanism. As part of the preoperative evaluation, dual-energy X-ray absorptiometry was used to assess the bone mineral density of the lumbar spine in 12 patients with neurofibromatosis-1, supplemented by laboratory blood/urine investigations. A significant decrease in bone mineral density of the lumbar spine was measured. An inverse relation was suggested between the severity of scoliosis and the lumbar spine Z-scores. No pivotal alterations were identified in the laboratory measurements. The bony tissue abnormality observed intraoperatively in neurofibromatosis-1 patients may be described as a diminution of the axial bone mineral density. The biochemical parameters do not support the presence of hyperparathyroidism, renal disorders or other associated diseases influencing the bone mineral turnover. The evaluation of bone mineral density in the course of the preoperative planning is proposed in neurofibromatosis-1; the exact background and the role of a possible osteoporosis in the prognosis remain to be elucidated. Received: 12 January 2001 / Accepted: 21 March 2001     

An Investigation of the Diagnostic Value of Bilateral Femoral Neck Bone Mineral Density Measurements

This paper describes a study to assess the clinical value of bilateral femoral neck bone mineral density (BMD) measurements. Although a range of factors will determine clinical decisions, the classification of the site with the lowest T-score is likely to have significant bearing on the management of a patient. While it is common practice to measure BMD at the lumbar spine and a single neck of femur, knowledge of the BMD of the second femur may also be of diagnostic value. Using dual-energy X-ray absorptiometry, BMD of the lumbar spine and right and left femoral neck was measured in a group of 2372 white, Caucasian women (mean age ± SD, 56.6 ±13.9 years) routinely referred for bone densitometry. Analysis of the measurements showed a significant (p= 0.02) but small difference between the mean BMD of the right (0.840 ± 0.152 g/cm²) and left (0.837 ± 0.150 g/cm²) femoral neck. Further investigation of femur scans revealed 79 (3.3%) patients in whom one side was osteoporotic while the other side and spine were normal or osteopenic using the World Health Organization diagnostic criteria in combination with manufacturer”s reference data. Patients in whom the femoral neck BMD measurements differed by less than the precision error of the system were then excluded. This left only 51 (2.2%) patients, that is 29 (1.2%) for right femur and spine scan and 22 (0.9%) for left femur and spine scan, in whom knowledge of both femoral neck BMD measurements could have altered the classification of the lowest site assessed to osteoporotic. These data suggest that there is only a small benefit from performing bilateral femoral neck BMD measurements. Since BMD measurements are only one of a range of factors considered as part of a patient”s management, it is suggested that the extra time, cost and radiation dose associated with measurement of the second femur may not be justified. Received: 28 October 1999 / Accepted: 2 February 2000     

Diet Acids and Alkalis Influence Calcium Retention in Bone

The urine-acidifying properties of food constituents depend on their content of non-oxidizable acids or precursors. Acidifying constituents such as animal proteins may negatively affect calcium metabolism and accelerate bone resorption, thus representing an aggravating factor for osteoporosis. This four-period, double-crossover study investigated whether a diet intervention specifically focused on acid load could modify calcium metabolism in humans. Eight healthy volunteers underwent a four-day metabolic preparation with two types of diets, one rich in acid ash-forming nutrients, and one providing base-forming nutrients (including bicarbonate-rich mineral water), both having similar contents of calcium, phosphate, sodium, proteins and calories. On the fourth day, a single oral dose of 1 g calcium was given, either as carbonate or as gluconolactate. Serial blood and urine samples revealed that the diet affected blood pH (average difference 0.014, p = 0.002) and urine pH (average difference 1.02, p<0.0001) in the expected direction, but had no influence on the absorption of the calcium supplement. The acid-forming diet increased urinary calcium excretion by 74% when compared with the base-forming diet (p<0.0001), both at baseline and after the oral calcium load, and C-telopeptide excretion by 19% (p = 0.01), suggesting a skeletal origin for the excess calcium output. This observation confirms that renally excreted acids derived from food influence calcium metabolism, and that alkalizing nutrients inhibit bone resorption. Further studies are needed to determine the clinical impact of dietary counseling for avoiding diet acids as a preventive measure against osteoporosis. Received: 6 October 2000 / Accepted: 22 February 2001     

Influence of Calcium Intake and Physical Activity on Proximal Femur Bone Mass and Structure Among Pre- and Postmenopausal Women. A 10-Year Prospective Study

This 10-year follow-up evaluated the effect of physical activity and calcium intake on proximal femur bone mass (BMC) and structural indices (CSA and Z) and physical performance. A cohort of 133 premenopausal and 134 postmenopausal women with contrasting levels of physical activity (high [PA⁺]) and low [PA⁻]) and calcium intake (high [Ca⁺] and low [Ca⁻]) was measured with DXA at baseline and 5 and 10 years thereafter. Among premenopausal women, the mean (95% CI) femoral neck BMC was 3.8% (−0.1 to 7.8%) and the trochanter BMC 6.7% (2.4 to 11.3%) greater in the PA⁺ group than the PA⁻ group. There was no difference between the Ca-intake groups. Among postmenopausal women, the mean femoral neck BMC was 4.2% (−0.2 to 8.8%) greater in the Ca⁺ group than in the Ca⁻ group and 6.9% (2.2 to11.8%) greater in the PA⁺ group than in the PA⁻ group. For trochanter BMC, the corresponding differences were 2.7% (−1.6 to 7.2%) and 5.5% (0.9 to 10.3%). The mean differences in CSA and Z were 3.8% (−0.9 to 8.7%) and 4.4% (−2.1 to 11.4%) in favor of the Ca⁺ group and 6.8% (1.9 to 12.0%) and 9.6% (2.5 to 17.1%) in favor of the PA⁺ group, respectively. Proximal femur BMC declined generally, but the initial differences between the physical activity and the calcium intake groups were maintained. High calcium intake seemed to slow the decline in trochanter BMC in premenopausal women, while high physical activity was beneficial for proximal femur, particularly among older women.     

The Influence of Physical Activity and Fractures on Ultrasound Parameters in Elderly People

In this cross-sectional study we investigated the relationship between ultrasound measurements in the calcaneus versus daily physical activity and fractures sustained in the past in elderly subjects. Ultrasound measurements were performed at both heels, which enabled us to examine determinants of differences between contralateral heels. Participants were 132 men and 578 women, aged 70 years and over (mean age and standard deviation (SD): 83 ± 6 years), living in homes for the elderly (n= 343) or apartment houses for the elderly (n= 367). Broadband ultrasound attenuation (BUA) and speed of sound (SOS) were measured in the right and left calcaneus. The median difference (and interquartile range) between the two heels for BUA and SOS, expressed as a percentage of the mean value for each individual, was 9.6% (4.2–15.7%) and 1.0% (0.4–1.7%), corresponding to 25% and 40% of the study population SD, respectively. Greater differences in BUA between the two heels were associated with variables indicating poorer functional status, such as past fractures at the lower extremities. The level of daily physical activity was obtained by means of a questionnaire regarding household and leisure activities. Subsequently sumscores were calculated for daily physical activity and a subscore indicating weight-bearing physical activity. After adjustment for age, gender, residence, and body weight, physical activity scores were positively linearly related to both BUA and SOS. Each 5 point increase on the weight-bearing physical activity score, corresponding to, for example, walking for 2.5 h per week, was associated with a difference in BUA of 4.7 dB/MHz and in SOS of 5.1 m/s, which is similar to the differences associated with 10 kg higher body weight, or 10 years younger age. After the age of 50 years, 47 subjects had fractured a hip, 61 subjects had sustained another lower extremity fracture, 104 subjects a wrist fracture, and 62 subjects another upper extremity fracture. After adjusting for age, gender and residence, odds ratios for all fracture types in the lowest terciles of BUA and SOS versus the highest terciles ranged from 1.9 to 3.8. This study showed significant differences in ultrasound measurements between the left and the right heel, indicating that measurements at both sides are necessary for optimal evaluation of bone strength. Furthermore, after careful adjustments, ultrasound parameters had higher values with higher daily physical activity in elderly subjects and discriminated subjects with a history of fracture from those without. Received: 26 June 1997 / Accepted: 1 February 1998     

Geographic Differences in Bone Mineral Density of Mexican Women

The aim of this study was to generate standard curves for normal spinal and femoral neck bone mineral density (BMD) in Mexican women using dual-energy X-ray absorptiometry (DXA), to analyze geographic differences and to compare these with “Hispanic” reference data to determine its applicability. This was a cross-sectional study of 4460 urban, clinically normal, Mexican women, aged 20–90 years, from 10 different cities in Mexico (5 in the north, 4 in the center and 1 in the southeast) with densitometry centers. Women with suspected medical conditions or who had used drugs affecting bone metabolism, were excluded. Lumbar spine BMD was significantly higher (1.089 ± 0.18 g/cm²) in women from the northern part of Mexico, with intermediate values in the center (1.065 ± 0.17 g/cm²) and lower values (1.013 ± 0.19 g/cm²) in the southeast (p<0.0001). Similarly, femoral neck BMD was significantly higher in women from the north (0.895 ± 0.14 g/cm²), intermediate in the center (0.864 ± 0.14 g/cm²) and lower (0.844 ± 0.14 g/cm²) in the southeast part of Mexico (p<0.0001). Northern Mexican women tend to be taller and heavier than women from the center and, even more, than those from the southeast of Mexico (p<0.0001). However, these differences in BMD remained significant after adjustment for weight (p<0.0001). A significant loss (p<0.0001) in BMD was observed from 40 to 69 years of age at the lumbar spine and up to the eighth decade at the femoral neck. Higher and lower lumbar spine values, as compared with the “Hispanic” population, were observed in Mexican mestizo women from the northern and southeastern regions, respectively. In conclusion, there are geographic differences in weight and height of Mexican women, and in BMD despite adjustment for weight. Received: 1 September 1999 / Accepted: 20 October 1999     

Exercise May Induce Reversible Low Bone Mass in Unloaded and High Bone Mass in Weight-Loaded Skeletal Regions

Exercise during growth and adolescence increases bone mineral density (BMD) in weight-loaded skeletal regions. The development of BMD in unloaded or minimally loaded regions during activity is unclear. We measured BMD in one unloaded, one partly loaded and one highly loaded skeletal region in 67 active soccer players, mean age 22.7 years (range 17–35 years), 128 former soccer players, mean age 54.0 years (range 19–85 years) and 138 controls, mean age 50.6 years (range 19–80 years). The active soccer players played at three different levels: premier league, 3rd league or 6th league. Duration of exercise in these three groups was 12, 8 and 6 h/week, respectively. BMD (g/cm²) was measured by dual-energy X-ray absorptiometry (DXA) in the upper part of the skull (the unloaded skeletal region), the arms (the partly loaded region) and the femoral neck (the maximal loaded region). Data are presented as mean ± SD. Active soccer players had 10.3 ± 10.4% lower BMD in the upper part of the skull (p<0.001), 1.4 ± 6.3% higher BMD in the arm (NS) and 12.7 ± 9.8% higher BMD in the femoral neck (p<0.001) compared with age- and gender-matched controls. All three levels of soccer players demonstrated, independent of activity level, the same discrepancies in BMD compared with controls. Former soccer players had lower BMD in the upper part of the skull until age 70 years and higher BMD in the femoral neck until age 50 years compared with controls. The BMD of the arm was not different in former soccer players compared with controls. In summary, active soccer players had lower BMD in the unloaded skeletal region, no difference in BMD in the partly loaded region and higher BMD in the weight-loaded region compared with controls. The discrepancies compared with controls diminished with age so that no differences were found in BMD after age 70 years. In conclusion, unloaded and weight-loaded skeletal regions may respond differently to increased and decreased physical activity. Received: 15 January 2001 / Accepted: 31 May 2001     

Relative Influence of Physical Activity, Muscle Mass and Strength on Bone Density

In a population-based sample of 348 men (age 22–90 years) and 351 women (age 21–93 years), we evaluated the relationship of bone density assessed at a variety of skeletal sites by dual-energy X-ray absorptiometry (DXA) with various muscle mass estimates obtained also from the DXA scan and with physical activity by interview and strength assessed both subjectively and objectively. All these parameters declined with age as judged from these cross-sectional data. All estimates of total skeletal muscle mass were strongly correlated with bone density at different skeletal sites. Muscle mass, in turn, was correlated with physical activity and hand strength. In multivariate models including these variables, muscle mass was the strongest determinant of bone density, accounting for 6–53% (mean 27%) of the variance at the different skeletal sites. Physical activity (and/or a physical activity × age interaction) was an independent predictor of bone mass in 48% of the site-specific models and accounted for 0.03–39% (mean 10%) of the variance, while hand strength (and/or a hand strength × age interaction) accounted for up to 4% (mean 1%) of the variance as an independent predictor of bone density in a third of the models. Although these variables together accounted for a large proportion of the variance in bone density, other potential predictors were not assessed in these analyses. The dramatic decline in physical activity over life seemed unable to completely explain the age-related loss of bone mass, and additional research is needed to determine whether the relationship of muscle mass with bone density is a direct one or due instead to other factors such as circulating hormone levels. Received: 2 December 1999 / Accepted: 12 May 2000     

Comparative Assessment of Bone Mineral Measurements Using Dual X-ray Absorptiometry and Peripheral Quantitative Computed Tomography

A measurement of bone mass is the single most important determinant of future fracture. However, controversy exists as to which technique (dual X-ray absorptiometry (DXA) or peripheral quanitative computed tomography (pQCT)), and which site of skeletal measurement (axial vs appendicular) provides the best prediction of fracture risk. The aims of this study were: (1) to determine the ability of pQCT to predict bone mass of the lumbar spine, proximal femur, and distal forearm measured using DXA, and (2) to compare the ability of DXA and pQCT to discriminate prevalent fractures in women with established osteoporosis. One hundred and sixty-five women were studied, including 47 with established osteoporosis (vertebral, hip or Colles' fractures) as well as 118 who had bone mass measurements to assess osteoporosis risk. Each subject had bone mass measured by DXA at the lumbar spine and femoral neck, and at the distal radius by both DXA and pQCT. In women with fractures, bone mass, when expressed as a standardized score, was in general lower using DXA compared with the appendicular skeleton measured using pQCT. Bone mass determinations at all sites were significantly correlated with each other. The highest correlation coefficients were observed within the axial skeleton. In women with fractures, the highest odds ratios were observed at skeletal regions measured using DXA. Likewise, the areas under the receiver-operating characteristic (ROC) curves were comparable at all skeletal regions measured using DXA; and were significantly greater than the areas under the ROC curves for pQCT measurements. In summary, the strongest discriminators of prevalent fractures were measurements using DXA. Measurements of bone mass at the appendicular skeleton, using either DXA or pQCT, were poorly associated with axial bone mass. PQCT has the poorer ability to discriminate persons with fractures, and appears to be less sensitive than measurements using DXA. Received: 15 September 1997 / Accepted: 17 February 1998     

Serum Albumin and Bone Mineral Density in Healthy Older Men and Women: The Rancho Bernardo Study

Serum albumin has been found to be positively correlated with bone mass in small studies of ambulatory men or women with diagnosed osteoporosis. In this study the relation between serum albumin and bone mineral density (BMD) was examined in 1593 white, community-dwelling men and women aged 50–95 years. BMD was determined using single-photon absorptiometry (SPA) at the ultradistal radius and the midshaft radius, and using dual-energy X-ray absorptiometry (DXA) at the hip and spine. Albumin was measured from a fasting blood sample using the Technicon SMA 12 autoanalyzer. Mean albumin levels in both men and women decreased significantly with increasing age. All but four values were within the normal range (3.5–5.0 g/dl). BMD decreased with increasing age at all sites. In both sexes there was weak positive correlation between serum albumin and BMD in the unadjusted model (Pearson's rvalues <0.3, p values <0.005). After age adjustment, however, the relationship was no longer significant (Pearson's r values <0.05, p values >0.18). Men and women were divided into three sex-specific categories – osteoporotic, osteopenic and normal – based on World Health Organization criteria in relation to young adult means (normal, BMD > –1 SD; osteopenia, BMD between –1 SD and –2.5 SD; osteoporosis, BMD <–2.5 SD). Mean albumin values did not differ significantly across the three BMD categories in men or women. BMD levels stratified for albumin levels and calcium supplement status (a marker for osteoporosis awareness) also did not differ. Albumin levels were also not associated with a history of low-trauma fractures. In summary, there was no age-independent association between serum albumin within the normal range and low BMD or fractures in community-dwelling healthy older adults. We conclude that previously reported associations most likely reflect inadequate adjustment for the age-related decrease in albumin levels and the selection of very frail osteoporotic subjects. Received: 7 October 1997 / Revised: 21 January 1998     

Total-Body Calcium Estimated by Delayed Gamma Neutron Activation Analysis and Dual-Energy X-ray Absorptiometry

Total body calcium (TBCa) in 270 black and white women age 21–79 years was measured concurrently by delayed gamma neutron activation analysis (DGNA) and dual-energy X-ray absorptiometry (DXA). The mean value for TBCa calculated from DXA was 933 g compared with 730 g for DGNA. By regression, TBCa_DXA(g)= 1.35 × TBCa_DGNA(g)−54 (r= 0.90, r ²= 81.4%, SEE = 66.9 g). This remarkable difference of 203 g suggests that one or both these methods is not accurate. Adjustment of the regression of DXA versus DGNA for body mass index or trunk thickness explained 8.5–10% of the variability between methods. The unadjusted slope for the DXA values regressed against the DGNA values was 1.35, indicating significant discordance between the methods. There is greater agreement between the two DGNA facilities (Brookhaven National Laboratory and Baylor College of Medicine) and between the various DXA instruments. Either DGNA underestimates TBCa or DXA overestimates total-body bone mineral content. Resolution of these disparate results may possibly be achieved by concurrent measurement of whole human cadavers of different sizes with chemical determination of the calcium content of the ash. In the interim, cross-calibration equations between DGNA and standardized values for DXA for total-body bone mineral content may be used, which will permit reporting of consistent values for TBCa from the two technologies. Received: 28 December 1998 / Accepted: 20 May 1999     

Effects of High-Intensity Resistance Training on Bone Mineral Density in Young Male Powerlifters

The effects of high-intensity resistance training on bone mineral density (BMD) and its relationship to strength were investigated. Lumbar spine (L2-L4), proximal femur, and whole body BMD were measured in 10 male powerlifters and 11 controls using dual-energy X-ray absorptiometry (DXA). There were significant differences in lumbar spine and whole body BMD between powerlifters and controls, but not in proximal femur BMD. A significant correlation was found between lumbar spine BMD and powerlifting performance. These results suggest that high-intensity resistance training is effective in increasing the lumbar spine and whole body BMD. Received: 27 February 1997 / Accepted: 23 March 1998     

Bone Mineral Density Differences at the Femoral Neck and Ward's Triangle: A Comparison Study on the Reference Data Between Chinese and Caucasian Women

The incidence of hip fracture is lower in Chinese women compared with those from western countries, though they usually have lower bone mineral density (BMD). In this study, reference data (from Caucasian women) supplied by the manufacturer of Hologic Inc. was compared with data obtained from healthy women in Changsha, Hunan province, P.R.C. A total of 1488 Chinese women aged 15–95 years were randomly chosen for the study. Measurements of BMD were taken at the hip by dual energy X-ray absorptiometry (DXA) (QDR 4500A, Hologic Inc., USA). The BMD and the BMD decrease rate were somewhat lower than reference curves at all age groups and all sites except for the femoral neck and Ward's triangle. Chinese women reached their peak BMD 5–10 years later than their counterparts, and had a lower BMD decrease rate for about 35 years after peak BMD was attained. The fact that Chinese women take longer time to reach peak BMD and have a lower BMD decrease rate at the neck and Ward's triangle after peak BMD is attained protects them against hip fractures, and is a phenomenon that needs to be studied in the future. Received: 11 May 1999 / Accepted: 29 February 2000