Osteoprotegerin, RANKL and bone turnover in postmenopausal osteoporosis.

BACKGROUND: Osteoprotegerin (OPG) and receptor activator of nuclear factor κ B ligand (RANKL) play a critical role in the regulation of bone turnover, but the relative importance of these two cytokines in the pathogenesis of postmenopausal osteoporosis is controversial. AIM: To investigate the relationship between circulating levels of OPG, RANKL, bone turnover and bone mineral density (BMD) in postmenopausal women. METHODS: A cross-sectional study of 185 women with osteoporosis and 185 age- and sex-matched control subjects was undertaken. Measurements were made of plasma OPG, RANKL, interleukin-6 (IL-6), sex steroids, calciotropic hormones, biochemical markers of bone turnover, BMD and anthropometry. Health questionnaires were administered. RESULTS: Plasma RANKL was significantly higher (p<0.0001) in women with osteoporosis (0.66±0.67 pmol/l) than in control subjects (0.37±0.38 pmol/l), as was plasma OPG (18.70±9.70 pmol/l in women with osteoporosis, 10.44±5.85 pmol/l in control subjects; p<0.0001). OPG/RANKL ratio was higher in women with osteoporosis (51.3) than in control subjects (36.6). The women with osteoporosis also had significantly higher biochemical markers of bone turnover, IL-6 and parathyroid hormone and lower 25-hydroxyvitamin D and oestradiol than the control subjects. Multiple regression analysis showed that lumbar spine and femoral neck BMD in postmenopausal women were best predicted by OPG and RANKL, giving an R(2) value of 15.5% and 14.9%, respectively. CONCLUSIONS: This study indicates that the circulating levels of OPG and RANKL are inversely related to BMD and contribute to the development of osteoporosis in postmenopausal women.

Peripheral dual-energy X-ray absorptiometry in the management of osteoporosis: the 2007 ISCD Official Positions.

Peripheral assessment of bone density using photon absorptiometry techniques has been available for over 40 yr. The initial use of radio-isotopes as the photon source has been replaced by the use of X-ray technology. A wide variety of models of single- or dual-energy X-ray measurement tools have been made available for purchase, although not all are still commercially available. The Official Positions of the International Society for Clinical Densitometry (ISCD) have been developed following a systematic review of the literature by an ISCD task force and a subsequent Position Development Conference. These cover the technological diversity among peripheral dual-energy X-ray absorptiometry (pDXA) devices; define whether pDXA can be used for fracture risk assessment and/or to diagnose osteoporosis; examine whether pDXA can be used to initiate treatment and/or monitor treatment; provide recommendations for pDXA reporting; and review quality assurance and quality control necessary for effective use of pDXA.

Ethnic and gender differences in body fat in British schoolchildren as measured by DXA.

BACKGROUND: There are known to be ethnic differences in body composition in adults which are related to ethnic differences in adult disease. OBJECTIVES: To evaluate gender and ethnic differences in percentage body fat in British schoolchildren and to compare these differences with classification of obesity using body mass index (BMI) criteria. DESIGN: A cross-sectional study of 1251 healthy children and adolescents aged 5-18 years from white, South Asian and African-Caribbean ethnic groups. Percentage body fat was determined by dual x ray absorptiometry and the subjects classified using BMI criteria for overweight and obesity. RESULTS: Significant gender differences in percentage body fat were seen, with girls having higher values from the age of 5 years. Girls had 3.8% higher percentage body fat at 5 years of age increasing to 12.9% at 18 years of age. Significant ethnic differences were found, with South Asian girls and boys having the highest percentage body fat from 5 and 7 years of age, respectively. These differences increased with age, being most significant in the teenage years. Although South Asian girls and boys were over-represented in the group containing children with more than 25% body fat (p<0.0001, chi2 test), African-Caribbean subjects were more likely to be classified as obese using BMI criteria. CONCLUSIONS: There are clear gender and ethnic differences in percentage body fat in British schoolchildren which may relate to known differences in the risk of type 2 diabetes in adolescence and adulthood. BMI criteria for defining overweight and obesity do not accurately identify ethnic differences in body fat.

Identification of men with reduced bone density at the lumbar spine and femoral neck using BMD of the os calcis.

We assessed the utility of os calcis (OC) bone mineral density (BMD) measurements to identify men with low BMD at the lumbar spine (LS) and femoral neck (FN). BMD was measured by dual X-ray absorptiometry (DXA). Receiver operator characteristics (ROC) analysis was applied to determine the risk of osteoporosis at the lumbar spine or femoral neck. [A total of 230 men with an average age of 59 yr were studied.] The most common reasons for referral were fracture (47%) and steroid use (46%). Twenty-six percent were osteoporotic at the LS, 21% at the FN, and 15% at the OC. Optimal classification with respect to osteoporotic measurements at the LS or FN was obtained at an OC T-score of -1.9 (BMD = 0.45 g/cm2). Osteoporosis was only weakly related to a simple cumulative risk factor score, but was strongly related to a T-score OC categorized into quartiles. Regression analysis of BMD on the major risk factors alone explained only 17% of the variance in BMD at the LS and 5% at the FN. The combination of the T-score at the OC, age, and weight provided the best model. BMD OC is superior to risk factors alone in the clinical evaluation and selection of men referred for axial densitometry.