Cytokine Production and Bone Mineral Density at the Lumbar Spine and Femoral Neck in Premenopausal Women

Cytokines such as interleukin-1 (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor (TNF-α) can influence both bone resorption and bone formation. The objective of this cross-sectional study was to examine the relationship between cytokine production by peripheral blood mononuclear cells (PBMC) and bone mineral density (BMD); the annual rate of change in BMD was examined. Subjects participating in a randomized clinical trial entitled the Women's Healthy Lifestyle Project in Allegheny County, Pennsylvania were used. They included 50 healthy premenopausal women, aged 45–52 years, who had regular menses within the past 3 months and were not on replacement estrogens. Dual-energy X-ray absorptiometry measurements at the AP lumbar spine and femoral neck were made at baseline and at the first annual exam using a Hologic QDR 2000 densitometer. Cytokine production of IL-1β, IL-6, and TNF-α by PBMC was measured at the annual exam. The median values for stimulated cytokine production by PBMC were 3.92 ng/ml, 31.3 ng/ml, and 1.05 ng/ml, for IL-1β, IL-6, and TNF-α, respectively. There were modest correlations between cytokine production and cross-sectional BMD, ranging from r =−0.30 to r =−0.13. Trends of greater spinal bone loss were observed in women with ``high' (≥75th percentile) cytokine production of stimulated IL-1β and IL-6 (IL-1β: ``high' =−1.56% ± 0.70 versus ``low' (<75th percentile) =−0.56% ± 0.35, P= 0.21). In contrast, greater annual gains in femoral neck BMD were observed in those with high cytokine production of IL-1β and IL-6 (IL-1β: high = 3.39% ± 1.16 versus low =−0.85 ± 0.58, P= 0.002). There was no association between stimulated TNF production and annual change in BMD. In this population of healthy premenopausal women, the relationship between cytokine production by PBMC and the rate of change in BMD was significantly different for the lumbar spine and femoral neck, possibly reflecting differences in the proportion of trabecular and cortical bone at these sites. Received: 5 February 1997 / Accepted: 11 May 1998     

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     

Bone Mineral Density of the Skull in Premenopausal Women

Dual-energy X-ray absorptiometry (DXA) of the head has received little attention. We used DXA to measure bone mineral density (BMD) of the entire skull including the mandible (BMD_Head) and BMD of the cranial vault (BMD_Vault) in 91 normal young women. We also measured BMD of the total body (BMD_{Total body}), proximal femur (``total femur'), and lumbar vertebrae (L1–L4). BMD (g/cm²; mean ± SE) was 1.032 ± 0.011 for L1–L4, 0.995 ± 0.011 for total femur, and 2.283 ± 0.028 for BMD_Vault (cranial vault) and the mean body weight of all subjects was 59.8 kg. Correlation between BMD_Vault and BMD_Head was 0.991 and this was not different from 1.0 (P= 0.473). The average difference between BMD_Vault and BMD_Head was −0.004 g/cm² suggesting that these two measurements of bone mass of the skull were similar. To determine the correlation between the different variables after accounting for external sources of variation, partial correlation derived from multiple regression was determined. Correlations between BMD at the various locations and with BMD_{Total body} were moderate to strong. Although small in magnitude, the partial correlations of body weight with BMD_{Total body}, total femur, and L1–L4 were significantly different from zero (P < 0.02). The results show that BMD_Vault, total femur, and L1–L4 were of equal value in predicting BMD_{Total body} and further, BMD_Vault was not influenced by body weight. Including body weight in multiple regression in addition to total femur or L1–L4 removed the extraneous variation due to body weight, and predictions of BMD_{Total body} were as reliable as when BMD_Vault was based on goodness of fit tests (P= 0.314). The technique used to measure BMD of the cranial vault is a relatively new variation of DXA technology. The precision was as good as other measurements of bone mass of the entire skull (including the mandible). Because the cranial vault is less sensitive to mechanical influences, it may be a region where response to therapy could be evaluated. The cranial vault may be a useful area to study certain heritable diseases that affect the skeleton, skeletal artifact, or evaluation of oral bone loss. Received: 22 December 1995 / Accepted: 24 September 1996     

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     

Long-Term Vegetarian Diet and Bone Mineral Density in Postmenopausal Taiwanese Women

This study examined bone density among postmenopausal Buddhist nuns and female religious followers of Buddhism in southern Taiwan and related the measurements to subject characteristics including age, body mass, physical activity, nutrient intake, and vegetarian practice. A total of 258 postmenopausal Taiwanese vegetarian women participated in the study. Lumbar spine and femoral neck bone mineral density (BMD) were measured using dual-photon absorptimetry. BMD measurements were analyzed first as quantitative outcomes in multiple regression analyses and next as indicators of osteopenia status in logistic regression analyses. Among the independent variables examined, age inversely and body mass index positively correlated with both the spine and femoral neck BMD measurements. They were also significant predictors of the osteopenia status. Energy intake from protein was a significant correlate of lumbar spine BMD only. Other nutrients, including calcium and energy intake from nonprotein sources, did not correlate significantly with the two bone density parameters. Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold (adjusted odds ratio = 2.48, 95% confidence interval = 1.03–5.96) and of being classified as having osteopenia of the femoral neck (3.94, 1.21–12.82). Identification of effective nutrition supplements may be necessary to improve BMD levels and to reduce the risk of osteoporosis among long-term female vegetarians. Received: 10 May 1996 / Accepted: 9 August 1996     

Body Size Accounts for Most Differences in Bone Density Between Asian and Caucasian Women

We compared bone mineral density (BMD) of the whole body (and subregions: arm, leg, and pelvis), hip, spine, lateral spine, wrist, and forearm among Caucasian and Asian women at four geographic centers (Honolulu, HI; Nottingham, UK; Portland, OR; Copenhagen, Denmark). Data were derived from the baseline examination of 1367 Caucasian and 162 Asian women enrolled in the 1609-subject Early Postmenopausal Interventional Cohort (EPIC) study. After adjusting for age, study site, years postmenopause, and years of estrogen use, BMD was approximately 4–6% lower (P < 0.05) among Asian women at most skeletal sites, but there was no significant difference for wrist or forearm BMD. Adding height, lean body mass, fat mass, and/or quadriceps muscle strength to the regression models reduced the racial differences at most skeletal sites; after these additional adjustments, Asian women had significantly lower BMD only for the lateral spine (−4.4%; P < 0.005), arm (−2.20%; P < 0.05) and leg (−1.65%; P < 0.05), whereas the wrist was significantly greater (4.64%; P < 0.005) for Asian women. Further research is needed to determine why racial differences in BMD persist at certain skeletal sites, but not others, after adjusting for body size. Received: 22 January 1996 / Accepted: 3 May 1996     

A Comparison Study of the Reference Curves of Bone Mineral Density at Different Skeletal Sites in Native Chinese,Japanese, and American Caucasian Women

To understand the differences among reference curves for bone mineral density (BMD) for Chinese, Japanese, and American Caucasian women, we measured the BMD at the anteroposterior (AP) lumbar spine (L1–L4), lateral lumbar spine (L2–L4), hip (including the femoral neck, trochanter, intertrochanter, Wards triangle, and total hip), and ultradistal forearm by the dual-energy X-ray absorptiometry (DXA) in a total of 2728 healthy Chinese women, aged 5–96 years. Documented BMD data for Japanese women and device manufacturers BMD new reference databases (including the NHANES III dataset) for American Caucasian women were also used in this study. The cubic regression model was found to fit best in analyzing the age-associated variations of BMD at various sites in Chinese women, i.e., the equations had the largest coefficient of determination (R ²). At the AP/Lat spine, trochanter, intertrochanter, and Wards triangle, BMD reference curves for Chinese women were lower than those for Japanese or Caucasian women, while at the femoral neck, total hip, and ultradistal forearm, the reference curves for Chinese women were higher than those for Japanese women, with overlaps and crossing of the curves for some age spans in comparing the Chinese and Caucasian women. There were significant differences in the peak BMD (PBMD) at various sites among the Chinese, Japanese, and Caucasian women (P = 0.000). The PBMDs for Chinese women at the lumbar spine and various sites of the hip were 5.7% ± 2.1% (mean ± SD, range, 2.7–7.9%) lower than those for Japanese women and 5.1% ± 2.7% (range, 0.5–7.2%) lower than those for Caucasian women; however, the PBMDs for Chinese women were 26.2% higher than those for Japanese women and 10% higher than those for Caucasian women at the ultradistal forearm. After the PBMD, average T-scores of Chinese women for losses at the AP lumbar spine with increasing age were nearly identical to those for Japanese women, but both were greater than those for Caucasian women. The average T-scores for BMD loss at various sites in Chinese women were higher than those for both Japanese and Caucasian women except at the femoral neck, where the T-scores of Chinese women were exceeded by those of both Japanese and Caucasian women. Estimated from the T-score curve of BMD loss, the age of osteoporosis occurrence at the femoral neck in Chinese women was about 10 years later than that in Japanese or Caucasian women; at the AP spine, Chinese women were similar to Japanese women; at the other sites, the age for occurrence of osteoporosis in Chinese women was about 5–15 years earlier than that in either Japanese or Caucasian women. There are differences in prevalence or odds ratio (OR) of osteoporosis at the same skeletal region for Chinese, Japanese, and Caucasian women aged 50 years or at different skeletal regions in women of the same race. The prevalences of osteoporosis at various regions of the hip in Chinese women are 10.1–19.8% and ORs are 22.0–32.3, of which prevalence at the femoral neck is the lowest (10.1%); the prevalences of osteoporosis in Japanese women are 11.6–16.8% and ORs are 21.1–26.3, of which prevalence at the femoral neck is the lowest (11.6%); and the prevalences of osteoporosis in Caucasian women are 13.0–20.0% and ORs are 19.4–48.9, of which prevalence at the femoral neck is the highest (20%). In conclusion, racial differences in BMD reference curves, prevalences, and risks of osteoporosis at various skeletal sites exist among native Chinese, Japanese, and American Caucasian women.     

Calcaneus Bone Mineral Density Using Single X-ray Absorptiometry in Japanese Women

Calcaneus bone mineral density (BMD) of 738 Japanese women (605 healthy and 133 with osteoporosis) was measured using single X-ray absorptiometry (SXA). A reference range of calcaneus BMD values for healthy Japanese women was established and the usefulness of this method for screening and diagnosis of osteoporosis was evaluated. There was no significant age change of calcaneus BMD prior to menopause, though values decreased significantly thereafter. BMD loss ratio was 1.7%/year in the 10 years after menopause. The reference range of calcaneus BMD was 410 ± 43 mg/cm², calculated from the mean BMD value of subjects whose ages ranged from 25 to 50 years old. The fracture threshold for the spine was established as 294 mg/cm², which corresponded to −2.67 SD from the average BMD of the young healthy women, and the odds ratio for spine fracture in the subjects with BMD lower than this threshold was 3.52 [95% CI (confidence interval) 1.34–9.26]. The spine fracture group showed statistically lower calcaneus BMD than the nonfracture group when subjects with adjusted age and body size were analyzed. There were no significant differences in the ROC analysis for spine fracture between calcaneus BMD and spine BMD. Therefore, calcaneus BMD is not readily affected by degenerative change or soft tissue, and the annual decrement rate (1.7%/year) can be detected easily and with low precision error (0.8%). These indices may prove useful for the screening and diagnosis of osteoporosis. Received: 16 September 1998 / Accepted: 28 January 1999     

Bone Density and Body Composition in Japanese Women

Total body bone mineral content (BMC_TB in g) and density (BMD_TB in g/cm²) and body composition were measured in 1006 healthy Japanese women aged 20–79 years using dual X-ray absorptiometry. Peak BMD_TB was 1.11 ± 0.05 g/cm² in women 20–49 years, and mean BMD_TB was 1.019 g/cm² in the 6th decade, 0.956 g/cm² in the 7th decade, and 0.900 g/cm² in the 8th decade. BMD_TB declined by 0.007 g/cm²/year in women after age 50. This age-related decline in BMD showed a similar pattern to that seen for the lumbar spine and femoral neck, but the actual rate of loss was lower for BMD_TB than for these other measurement sites. There was no significant difference between a eumenorrheic premenopausal group and a group with irregular menses. BMC_TB and BMD_TB were associated with body build, lean tissue mass, and fat mass (r = 0.29 ∼ 0.65 and 0.26 ∼ 0.41, respectively). Bone mass and density decreased significantly in older women of all body builds. Premenopausal Japanese women had a 5% lower BMD_TB than U.S. and European whites, but the difference was several times greater in postmenopausal than in premenopausal women. Received: 1 June 1995 / Accepted: 3 March 1997     

Osteoporosis After Gastrectomy: Bone Mineral Density of Lumbar Spine Assessed by Dual-Energy X-ray Absorptiometry

Although osteoporosis is a common clinical disorder associated with gastric surgery, long-term effects of gastrectomy on bone metabolism are still unclear. The purpose of this study was to clarify the incidence and risk factors of osteoporosis after gastrectomy using univariate and multivariate analyses of quantitative measurements. The study included 59 patients who had undergone gastrectomy more than 5 years before. There were 38 men and 21 women, aged 37–81 years, mean 64 years. Bone mineral density (BMD) of L2–L4 spine was measured using dual-energy X-ray absorptiometry (DXA). Absolute value of BMD (g/cm²) and age- and sex-matched BMD (%) were given. The mean BMD was 0.766 g/cm², and the incidence of osteoporosis (BMD less than 0.70 g/cm²) was 37%: 18% in men and 71% in women. The mean age- and sex-matched BMD was 85.9%: 87.5% in men and 83.1% in women. Univariate and multivariate analyses revealed that BMD was significantly associated with the age and sex of patients, but was not influenced by the type of gastrectomy (partial versus total) and years after operation (<20 versus 20<). Our study clarified the fact that postgastrectomy osteoporosis was frequent in the aged or female patients. BMD should be evaluated after gastrectomy, especially in the aged and in women. Received: 5 January 1998 / Accepted: 13 August 1999     

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     

Bone Mineral Density of Patients with Thalassemia Major: Four-Year Follow-Up

The purpose of this study was to evaluate the bone mineral density (BMD) of 50 patients aged 9–28 years, with thalassemia major and to assess the alterations of bone density in a 4-year follow-up study. They were measured with a DPX densitometer at the lumbar spine and femur area and divided into three groups: preadolescents, adolescents, and adults. All patients received calcium and vitamin D supplements, and 8 of the 50 received hormone replacement therapy (HRT). All patients had a significantly lower BMD compared with healthy subjects. Mean values of lumbar BMD of the three groups were 1.3, 2, and 3 standard deviations (SDs) lower than those of healthy subjects of the same age. All adolescent patients with normal gonadal function and those who received HRT showed an increase in BMD during the period of the study. Adult patients also showed an increase in bone density as long as the treatment lasted. However, adolescent and adult patients who had hypogonadotropic hypogonadism but could not get therapy showed a decrease in bone density. BMD of patients with thalassemia major shows a good index of bone status which should be evaluated, especially for the determination and follow-up of therapy. Received: 31 March 1997 / Accepted: 1 November 1998     

Bone Mineral Density in Athletes During and After Career: A Comparison Between Loaded and Unloaded Skeletal Regions

Bone mineral density (BMD) was measured in the upper part of the skull, the femoral neck, and the total body by dual energy X-ray absorptiometry in 56 male and 33 female active athletes, 18–40 years of age, together with 64 male ex-weight lifters, 35–79 years of age. The active athletes were compared with 41 male and 54 female controls, the ex-weight lifters with 133 male controls. The purpose of the study was to see if BMD in the upper part of the skull, a region virtually unaffected by physical load, is different in athletes and controls. The male athletes had a 3% higher BMD for the total body and 12% for the hip, whereas the BMD for the upper part of the skull was 10% lower than controls. Corresponding BMD values for the female athletes were 4% higher for total body and 10% for the femoral neck, and the upper part of the skull was 7% lower than in controls. After 65 years of age there was no difference in BMD comparing ex-weightlifters and controls. Using a constructed ratio BMD total body to BMD upper part of the skull, the ex-weight lifters had 10% higher values also after age 65. It appears that bone mass is higher in weight-loaded areas and lower in an unloaded region, such as the upper part of the skull, in exercising athletes. After cessation of the active career, the bone mass approaches that of the controls and after 65 years of age, no difference was found comparing ex-weight lifters and controls. Due to the apparent bone mass shift from unloaded skeletal regions to loaded skeletal regions that seems to take place in active athletes, the constructed ratio, BMD total body to BMD upper part of the skull, seems to discriminate the influence on the skeleton in a more sensitive way than measuring the BMD in defined skeletal regions on their own. By using this constructed ratio, the influence on bone mass of physical exercise early in life is also detectable at older ages. Received: 6 June 1995 / Accepted: 1 April 1996     

Bone Mineral Density, Body Mass Index, and Hip Axis Length in Postmenopausal Cretan Women with Cervical and Trochanteric Fractures

We assessed the bone mineral density (BMD), the body mass index (BMI), and the hip axis length (HAL) in 78 postmenopausal women with 38 cervical and 40 trochanteric hip fractures. The results were compared with those of age-matched, control postmenopausal women. No statistically significant difference was found in the values of BMD, BMI, and HAL between the groups of patients with cervical and those with trochanteric fractures, but lower BMD and BMI were found in fracture patients compared with the corresponding values of the control subjects. Contrary to the existing data, HAL was found to be shorter in the fracture patients compared with the controls. Thus, the type of hip fracture was found to be independent of the value of BMD, BMI, and the length of the patient's hip axis. The fact that a shorter hip axis was found in the group of fracture patients compared with that found in the control subjects raises questions about the significance of this parameter as an independent risk factor for hip fracture. Received: 9 February 1998 / Accepted: 24 June 1998     

Biochemical Markers of Bone Turnover and Bone Loss at the Lumbar Spine and Femoral Neck: The Taiji Study

The purpose of this study was to ascertain whether biochemical markers of bone turnover predict bone loss. The survey was carried out in Taiji, Wakayama Prefecture, Japan. From a list of inhabitants aged 40–79 years, 400 participants (50 men and 50 women in each of four age groups) were selected randomly. Bone mineral density (BMD) was measured, and blood and urine samples of all participants were examined to obtain values for eight biochemical markers: alkaline phosphatase (ALP), bone Gla protein (BGP), type I procollagen (carboxyterminal peptide of type I procollagen; PICP), cross-linked carboxyterminal telopeptide region of type I collagen (ICTP), and urinary excretion of calcium (Ca), phosphate (P), pyridinoline (Pyr), and deoxypyridinoline (D-Pyr). Each marker was evaluated as a predictor of the rate of bone change in lumbar spine and femoral neck BMD over a 3-year period. The value of Pyr was significantly related to the change of lumbar spine BMD in men (P= 0.009), and that of BGP was found to be significant in women (P= 0.045). By contrast, none of the bone markers significantly correlated with bone loss at the femoral neck. The coefficient of determination at the lumbar spine was 5% and 7% at the femoral neck only. We conclude that biochemical markers of bone turnover cannot predict bone loss rates in middle-aged or elderly Japanese men and women over a 3-year period with sufficient accuracy for use in clinical decision making. Received: 26 January 1998 / Accepted: 9 July 1998     

Differences in Bone Resorption after Menopause in Japanese Women with Normal or Low Bone Mineral Density: Quantitation of Urinary Cross-Linked N-Telopeptides

The objective of this study was to examine the value of NTx, a urinary cross-linked N-telopeptides of type I collagen, as a marker of bone resorption. We assessed changes in pre- and postmenopausal bone resorption by evaluating the correlation of NTx with L2–4 bone mineral density (BMD) in a total of 1100 Japanese women, aged 19–80 years [272 premenopausal (45.2 ± 6.2 years) and 828 postmenopausal (59.5 ± 6.2 years)]. Postmenopausal women were divided into three groups based on the range of BMD (normal, osteopenic, and osteoporotic). Within each group, subjects were further segregated according to years since menopause (YSM). NTx values were then evaluated for each group. Our results showed that BMD was significantly decreased (P < 0.05) and NTx was significantly increased (P < 0.01) after menopause in age-matched analysis. Consistent with a previous report, NTx was inversely correlated with BMD for the entire cohort of study subjects (r =−0.299), although NTx correlated better with premenopausal than postmenopausal BMD (r =−0.240 versus r =−0.086). This may have been due to the fact that elevated values of NTx were exhibited over the entire range of BMD present in the postmenopausal women, suggesting that NTx might respond faster to the estrogen withdrawal than BMD. In all postmenopausal women, regardless of the range of BMD, the increase in NTx reached a peak within 5 YSM. After 11 YSM, however, NTx remained elevated in the osteoporotic group but it decreased in the osteopenic group, and showed no significant change in the group of postmenopausal women with normal BMD. These findings suggest that bone resorption is dramatically increased within 5 years after menopause but remains increased only in osteoporotic women. Received: 29 April 1997 / Accepted: 12 August 1997     

A Prospective Study of Bone Mineral Density Change in Taiwan

In 1989, a cross-sectional study was carried out in Lin-Kou Township, Taiwan, to determine the distribution of bone mineral density (BMD) in the lumbar spine of Chinese people. Lumbar spine BMD was measured using dual-photon absorptiometry in 404 healthy volunteers (266 women and 138 men, aged 15 to 83 years). In 1994–1995, 318 of the same volunteers were reexamined for the present study. Except for there being fewer males and smokers present, there were no significant differences between the second survey respondents and nonrespondents. Spine BMD decreased at over 1% per year in Chinese women over age 50, which was somewhat higher than reported for caucasian women. Since there was a loss of BMD in Chinese women after their 20s, a case can be made for starting preventive activities for female adolescents. There were no differences in the mean BMD change rates among the different age groups of Chinese men. Baseline BMD, menopause, and weight change were associated with the lumbar spine BMD change rates in Chinese women. Body mass index was the only variable significantly associated with BMD change in Chinese men. The rate of BMD change was not associated with diet. Received: 18 February 1997 / Accepted: 5 June 1997     

Discordance Between Ultrasound of the Calcaneus and Bone Mineral Density in Black and White Women

Black women have 40% of the incidence rate for hip fracture and have a higher bone mineral density (BMD) than white women. The possibility was raised that bone quality may be disproportionately greater than the advantage in bone density in protection against osteoporotic fractures in black versus white women. Ultrasound (US) of the calcaneus is believed to measure properties of bone in addition to its density. We performed bone density measurements and US of the calcaneus in 108 black and 177 healthy white women, aged 20–70 years. The highest correlation was seen between total body bone density and speed of sound (r = 0.75). The interracial differences in BMD were all statistically significant and varied from 3.4 to 7.6%. The US measurements had lesser interracial differences than the bone density measurements, with velocity barely different between races. These findings suggest that US of the calcaneus measures properties of bone different from density. Fracture prediction data using US from prospective data in white women should not be extrapolated to black women because of the discordance between bone density and US measurements. Prospective studies are needed comparing US measurements in black women to the occurrence of osteoporotic fractures. Received: 30 May 1997 / Accepted: 8 January 1998     

Anomalies in the Measurement of Changes in Bone Mineral Density of the Spine by Dual-Energy X-ray Absorptiometry

Dual-energy X-ray absorptiometry (DXA) is frequently used for longitudinal studies of bone mineral status because of the high precision obtained, but evidence is emerging that the accuracy of measurements of changes may be a limitation because of artefacts of the analysis procedure, in particular, a dependence of the measured bone area (BA) on the bone mineral content (BMC). Results of spine bone mineral measurements taken at intervals with two DXA scanners, a Hologic QDR 1000W, and a Norland XR 26 HS, were examined. There was a consistent correlation between changes in BA and in BMC, with a slope of approximately 0.25 when expressed as percentages. A real change of BA of the magnitude observed is not feasible. There were no differences among the correlations for different instruments, genders, ages, or weight changes. There would appear to be an underestimation of changes in bone mineral density (BMD), but there is a possibility that some of the anomaly is manifested as an overestimation of a change in BMC. Phantom measurements were undertaken with the DXA scanners mentioned above and with a Lunar DPX. The phantoms consisted of simulations of the spine cut from aluminium sheet, so that the effective BMD could be varied. The dependence of the measured BA on BMC varied with the phantom outline, particularly the thickness of the transverse processes. Evidence was obtained of both an underestimate of BMD changes and an overestimate of BMC changes. There are errors in measuring spine changes, but these do not seem to be as serious as a previous report suggests for the Hologic scanner and are not likely to lead to misinterpretation of results. Received: 17 June 1997 / Accepted: 23 January 1998     

Dual Energy X-Ray Absorptiometry in Small Rats with Low Bone Mineral Density

The feasibility of dual energy X-ray absorptiometry (DXA) using the Norland XR-26 Mark II bone densitometer for measurements of bone mineral content (BMC) and bone mineral density (BMD) in small rats was evaluated. Thirty-two young, isogenic, Lewis rats (weights from 119 g to 227 g) were used; normal rats (n = 7) and rats with low BMD obtained from three different vitamin D-depleted models (n = 25). DXA measurements were performed using the special software for small animals. Duplicate scans of excised femurs performed at 2 mm/second (pixel size of 0.5 mm × 0.5 mm) were very precise measurements with a coefficient of variation (CV) below 1.6% in animals with normal BMD; in rats with low BMD, the CV was significantly higher (P= 0.02–0.04), 7.8% and 4.4% for BMC and BMD, respectively. Regression analysis demonstrated that these measurements were related to the ash weight (R² > 98.6%). The CV for measurements of the lumbar spine at 10 mm/second (pixel size 0.5 mm × 0.5 mm) was 2.6% and 2.2% for BMC and BMD, respectively in rats with normal BMD, and again higher (P= 0.03–0.14) in rats with low BMD, 7.3% and 4.7%, respectively, for BMC and BMD. Even though low CVs were obtained for total body duplicate scans (scan speed of 20 mm/second and a pixel size of 1.5 mm × 1.5 mm), the measurements were problematic for accuracy because of an overestimation of both BMC and the area of bone. Using these scan parameters the measurements of total body bone mineral could not be recommended in small rats with low BMD. Received: 21 May 1999 / Accepted: 3 August 2000 / Online publication: 22 December 2000