Endocrine and physical determinants of bone mass in late postmenopause

Performance of five phalangeal QUS parameters in the evaluation of gonadal-status, age and vertebral fracture risk compared with DXA

The aim of this cross-sectional study was to study the value of five different quantified ultrasound (QUS) parameters-amplitude-dependent speed of sound (AD-SoS), Ultrasound Bone Profile Index (UBPI), fast-wave amplitude (FWA), bone transmission time (BTT) and signal dynamic (SDY)-measured at the phalanges of the hand in discriminating women with vertebral fracture and their relationship with some determinants of bone mass, in particular age and gonadal status compared with lumbar spine and hip dual-energy x-ray absorptiometry (DXA). We included 791 women aged 35-84 y, divided into pre-menopause, early menopause and late postmenopause groups on the basis of gonadal status and years since menopause (YSM). The presence of vertebral fracture was evaluated radiographically. All QUS parameters were very sensitive to changes in early postmenopause, with a doubled decrease in early postmenopausal with respect to late postmenopause. In particular AD-SoS and BTT decreases were markedly high in the early postmenopause group. In the late menopause group, similar decreases were observed for AD-SoS, UBPI and hip bone mineral density (BMD). In the multiple logistic model, DXA and QUS significantly discriminate women with and without fractures (p < 0.0001); odds ratio (OR) was higher at lumbar spine BMD (OR 4.01), FWA (OR 3.88), AD-SoS (OR 3.81) and total hip BMD (OR 3.77). Even adjusting the logistic model for age, height, weight, lumbar spine and total hip BMD, all QUS parameters remained significantly predictive of vertebral fracture. AD-SoS showed the best performances both in terms of OR and ROC analysis. QUS parameters show a different behavior in evaluating the effect on bone mass of the time since menopause; AD-SoS and BTT showed a high sensitivity to first changes in bone tissue after menopause. After correction for potential confounders, AD-SoS showed the same ability of lumbar spine BMD in discriminating women with or without vertebral fractures and in the prediction of fracture risk.

Evaluation of methods for prediction of bone mineral density by clinical and biochemical variables in perimenopausal women

OBJECTIVES

to predict spinal and femoral bone mineral density (BMD) in perimenopausal women from simple clinical and biochemical variables.

METHODS

2016 women 3-24 months past last menstrual bleeding. Mean age 50.1+/-2.8 years. Age, height, weight, number of full term pregnancies, weekly hours of physical activity, sunbathing habits, use of sun bed, daily intake of calcium and vitamin D, smoking habits, consumption of alcohol, coffee, and tea, history of forearm or femoral neck fractures among the parents, serum osteocalcin (S-OC), serum bone specific isoenzyme of alkaline phosphatase (BSAP), and urine hydroxyproline/creatinine ratio (U-OHP) were used as predictors in three different mathematical models. Lumbar spine (L2-L4) and femoral neck BMD were measured by DEXA. Three mathematical models (multiple regression, logistic regression, and discriminant analysis) were applied.

RESULTS

the multiple regression explained 19-21% of the total variation, and the logistic regression and discriminant function had a sensitivity between 53 and 67% with specificity ranging from 67 to 80%. Age, S-OC, serum bone specific alkaline phosphatase, and a maternal history of forearm or femoral neck fractures seemed to be reproducible risk factors for low bone mineral density irrespective of the mathematical model applied. When applied to a separate population, the models performed poorly.

CONCLUSIONS

Simple clinical and biochemical variables are not useful to predict spinal and femoral BMD in the individual perimenopausal woman.

The pathophysiological implications of circulating androgens on bone mineral density in a normal female population

In this cross-sectional study performed on 147 healthy or osteoporotic, but otherwise normal premenopausal (n = 26 and n = 13, respectively) or postmenopausal (n = 40 and n = 68, respectively) women aged 40.1+/-9.9 and 61.9+/-8.9 years, respectively (range 20-82 years), serum ovarian and adrenal sex steroids and their relationship to bone mineral density (BMD) were evaluated. The levels of dehydroepiandrosterone sulfate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (AD), and estradiol correlated positively with BMD at the hip and spine as did serum testosterone with BMD at the spine. An inverse relationship was found between sex hormone binding globulin (SHBG) levels and BMD at the spine and hip. After adjustment for age, body mass, and sex steroid confounders, the bioavailable testosterone value (but not the DHEAS, DHEA, AD, or SHBG) values was demonstrated to be an independent determinant of BMD at the spine (beta 0.18, P<0.02) and hip (beta 0.24, P<0.02). Similarly, estradiol was found to be an independent determinant of BMD at the spine (beta 0.25, P<0.007). However, only SHBG levels (but not other steroid parameters) correlated positively with indices of bone remodeling, namely, serum osteocalcin and cross-linked telopeptide of type I collagen (ICTP). The present study suggests that a major decline in index of free testosterone (testosterone/SHBG) may influence the development of female osteoporosis. The clinical significance of circulating SHBG levels in the assessement of bone metabolic turnover remains to be established.

Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women

OBJECTIVES

To determine the relationships between serum vitamin D metabolites, bone mass, and dietary calcium and phosphorus in a cohort of 510 healthy Danish perimenopausal women.

DESIGN

A population-based cross-sectional study.

SUBJECTS

A total of 510 healthy women aged 45-58 years, with amenorrhoea for 3-24 months. None of the women was using hormone replacement therapy.

MEASUREMENTS

Measurements of total bone mineral content and regional bone mineral density were performed by dual-energy X-ray absorptiometry. Analyses of serum levels of 25-OHD and 1,25-(OH)2D, intact PTH, ionized calcium and phosphate, as well as biochemical markers of bone turnover in blood and urine. Assessment of calcium and phosphorus intake using dietary records.

RESULTS

A consistent inverse relationship between serum 1,25-(OH)2D and bone mineral content/ density was found in whole-body mineral content (P = 0.001), spine (P = 0.005) and femoral neck (P<0.05). There was a positive relationship between levels of 1,25-(OH)2D and biochemical bone markers, indicating that high levels of 1,25-(OH)2D are accompanied by increased bone turnover. The dietary calcium:phosphorus ratio was inversely related to serum 1,25-(OH)2D (P = 0.04) and positively related to bone mineral density (P<0.0005). No relationships could be detected between levels of PTH, serum ionized calcium and phosphate, and serum vitamin D metabolites.

CONCLUSION

Within normal physiological range, elevated levels of 1,25-(OH)2D were associated with decreased bone mineral density and content, reduced calcium:phosphorus ratio in the diet and increased bone turnover.