Spinal trabecular bone loss and fracture in American and Japanese women.

Background:Thyroid hormones affect bone remodeling in patients with thyroid disease by acting directly or indirectly on bone cells. In view of limited information on correlation of thyroid function with bone mineral density (BMD) in euthyroid subjects, we undertook this study to evaluate the correlation between thyroid function with BMD in subjects with normal thyroid function and subclinical hypothyroidism.Material and Methods:A total of 1290 subjects included in this cross sectional study, were divided in Group-1 with normal thyroid function and Group-2 with subclinical hypothyroidism. Fasting blood samples were drawn for the estimation of serum 25(OH)D, intact parathyroid hormone, total and ionized calcium, inorganic phosphorus, and alkaline phosphatase. BMD at lumbar spine, femur, and forearm was measured.Results:BMD at all sites (radius, femur, and spine) were comparable in both groups. There was no difference in BMD when subjects were divided in tertiles of TSH in either group. In group-1, FT4 and TSH were positively associated with BMD at 33% radius whereas FT3 was negatively associated with BMD at femoral neck in multiple regression analysis after adjustment for age, sex, BMI, 25(OH)D and PTH levels. In group-2, there was no association observed between TSH and BMD at any site. Amongst all study subjects FT4 and FT3 were positively correlated with BMD at lumbar spine and radius respectively among all subjects.Conclusion:TSH does not affect BMD in euthyroid subjects and subjects with subclinical hypothyroidism. Thyroid hormones appear to have more pronounced positive effect on cortical than trabecular bone in euthyroid subjects.

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, Ward's 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 manufacturer's 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 (R2). At the AP/Lat spine, trochanter, intertrochanter, and Ward's 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 > or = 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.

Strategies for the prevention and treatment of osteoporosis during early postmenopause

In order to determine the age and menopause-related changes in spinal bone mineral density (BMD) in healthy Japanese women, the spinal BMD at L(2-4) was measured by dual X-ray absorptiometry (DXA) in 172 healthy Japanese women aged 31-69 years (mean age 53.1+/-6.7 years) in 1990 and 2000. This prospective study showed that there was no significant decrease of BMD in premenopausal women, but there was a significant decrease of BMD (-1.59%/year) in the early post menopausal women when compared with the premenopausal and late postmenopausal women (P <0.0001). The rate of decrease in BMD slowed down with the prolongation of the years since menopause (YSM). In postmenopausal women the annual rate of decrease in BMD for obese women was significantly lower than that for slim ones (P <0.01), suggesting that fat tissue may be effective for preventing bone loss. A multiple regression analysis of variables contributing to the annual rate of decrease in spinal BMD showed that YSM and physiological age were the most influential factors, considering other factors such as weight, height and bone mass index. In conclusion, an accelerated bone loss was seen in the early postmenopausal stage. The YSM and physiological age were the most important factors that affect the rate of bone loss in healthy postmenopausal Japanese women.

When and how should bone mineral density be measured?

Association of Bone Mineral Density With Deformity of the Distal Radius in Low-Energy Colles' Fractures in Japanese Women Above 50 Years of Age

As aconsequence of the exponential BMD/fracture risk relationship,very small increases in BMD can be expected to have very largeeffects on reducing fracture rates (Fig. 1). It is not necessary todouble BMD to reduce fractures by a factor of 2.On the basis of the established relationships betweenBMD, bone strength, and fracture risk, current therapies forreducing fractures have been targeted at reversing bone lossto increase bone strength. Several different therapies havebeen shown to increase bone density and reduce frac-tures.

Surrogates for fracture endpoints in clinical trials.

The Val432Leu polymorphism of the CYP1B1 gene is associated with differences in estrogen metabolism and bone density

Arterial calcification and osteoporosis commonly accompany one another in postmenopausal women. Hypertension is a known contributing factor to arterial calcification. Thus, we aimed to investigate any associations between hypertension, arterial calcification and vertebral fractures in a cross-sectional study in Japanese postmenopausal women. The medical histories of 421 postmenopausal Japanese women diagnosed with hypertension, diabetes mellitus or hyperlipidemia were investigated. Bodyweight, body height and ultradistal bone mineral density (BMD) were measured. The prevalent vertebral fractures were diagnosed by a semiquantitative method, and the number of breast arterial calcifications (BAC) was investigated by mammography screening. Patients with vertebral fractures were of a significantly higher age, lower height, lower ultradistal BMD and had a higher number of BAC compared with those without vertebral fractures. Furthermore, a significantly higher prevalence of hypertension was observed in the patients with vertebral fractures as compared with those without. A multivariate stepwise regression analysis using these variables for vertebral fractures showed that the significant odds ratios (OR) of age (OR 1.76, 95% CI 1.11-2.77, P = 0.016), the prevalence of BAC (OR 2.52, 95% CI 1.62-3.93, P < 0.001) and the presence of hypertension (OR 1.76, 95% CI 1.11-2.80, P = 0.017) were found as significant independent risk factors for vertebral fractures. This is the first report of the relevance of BAC or hypertension to vertebral fractures in Japanese women. The results suggest that hypertension, BAC and osteoporotic fractures share a common metabolic pathway in their pathogenesis.

AB0711 USEFULNESS OF THE TRABECULAR BONE SCORE AS A PREDICTOR OF VERTEBRAL FRACTURE IN PATIENTS WITH AXIAL SPONDYLOARTHROPATHY

Bone mass in females with different thyroid disorders: influence of menopausal status

Bone mineral density (BMD) and fracture rates vary among women of differing ethnicities. Most reports suggest that BMD is highest in African-Americans, lowest in Asians, and intermediate in Caucasians, yet Asians have lower fracture rates than Caucasians. To assess the contributions of anthropometric and lifestyle characteristics to ethnic differences in BMD, we assessed lumbar spine and femoral neck BMD by dual-energy x-ray absorptiometry in 2277 (for the lumbar spine) and 2330 (for the femoral neck) premenopausal or early perimenopausal women (mean age, 46.2 yr) participating in the Study of Women's Health Across the Nation. Forty-nine percent of the women were Caucasian, 28% were African-American, 12% were Japanese, and 11% were Chinese. BMDs were compared among ethnic groups before and after adjustment for covariates. Before adjustment, lumbar spine and femoral neck BMDs were highest in African-American women, next highest in Caucasian women, and lowest in Chinese and Japanese women. Unadjusted lumbar spine and femoral neck BMDs were 7-12% and 14-24% higher, respectively, in African-American women than in Caucasians, Japanese, or Chinese women. After adjustment, lumbar spine and femoral neck BMD remained highest in African-American women, and there were no significant differences between the remaining groups. When BMD was assessed in a subset of women weighing less than 70 kg and then adjusted for covariates, lumbar spine BMD became similar in African-American, Chinese, and Japanese women and was lowest in Caucasian women. Adjustment for bone size increased values for Chinese women to levels equal to or above those of Caucasian and Japanese women. Among women of comparable weights, there are no differences in lumbar spine BMD among African-American, Chinese, and Japanese women, all of whom have higher BMDs than Caucasians. Femoral neck BMD is highest in African-Americans and similar in Chinese, Japanese, and Caucasians. These findings may explain why Caucasian women have higher fracture rates than African-Americans and Asians.

Background:Osteoporosis is defined as a bone mineral density (BMD) of at least 2.5 standard deviations below the young adult mean (YAM) (T-score ≤2.5) according to World Health Organization criteria, or...

Determinants of vertebral fracture prevalence among native Japanese women and women of Japanese descent living in Hawaii.