Age, steroids and bone mineral content

Associations between genetic variants and the effect of letrozole and exemestane on bone mass and bone turnover

Adjuvant therapy for hormone receptor (HR) positive postmenopausal breast cancer patients includes aromatase inhibitors (AI). While both the non-steroidal AI letrozole and the steroidal AI exemestane decrease serum estrogen concentrations, there is evidence that exemestane may be less detrimental to bone. We hypothesized that single nucleotide polymorphisms (SNP) predict effects of AIs on bone turnover. Early stage HR-positive breast cancer patients were enrolled in a randomized trial of exemestane versus letrozole. Effects of AI on bone mineral density (BMD) and bone turnover markers (BTM), and associations between SNPs in 24 candidate genes and changes in BMD or BTM were determined. Of the 503 enrolled patients, paired BMD data were available for 123 and 101 patients treated with letrozole and exemestane, respectively, and paired BTM data were available for 175 and 173 patients, respectively. The mean change in lumbar spine BMD was significantly greater for letrozole-treated (-3.2 %) compared to exemestane-treated patients (-1.0 %) (p = 0.0016). Urine N-telopeptide was significantly increased in patients treated with exemestane (p = 0.001) but not letrozole. Two SNPs (rs4870061 and rs9322335) in ESR1 and one SNP (rs10140457) in ESR2 were associated with decreased BMD in letrozole-treated patients. In the exemestane-treated patients, SNPs in ESR1 (Rs2813543) and CYP19A1 (Rs6493497) were associated with decreased bone density. Exemestane had a less negative impact on bone density compared to letrozole, and the effects of AI therapy on bone may be impacted by genetic variants in the ER pathway.

The relationship between serum dehydroepiandrosterone sulfate concentration and bone mineral density, lipids, and hormone replacement therapy in premenopausal and postmenopausal women

OBJECTIVE

To investigate the relationship between serum dehydroepiandrosterone sulfate (DHEAS) concentration and bone mineral density (BMD), lipids, and hormone replacement therapy (HRT) in postmenopausal women.

METHODS

Two hundred twenty-seven women aged >40 years were admitted to the study and divided into three groups: 61 premenopausal normally menstruating women, 108 postmenopausal women who were not receiving HRT, and 58 postmenopausal women receiving HRT. DHEAS levels and lipid patterns were measured. BMD measurements of the lumbar spine (L1-L4) were performed by dual-energy x-ray absorptiometry (DXA).

RESULTS

A positive correlation between DHEAS levels and BMD was found in all three groups. A linear regression model was used to assess the effect of age, body mass index (BMI), parity, and BMD of lumbar vertebrae (L1-L4) on changes in the serum level of DHEAS and found that aging and BMD at the spine had a significant association with serum level of DHEAS and only aging after adjustment for age, BMI, parity, and lipid patterns among the three groups. Age (RR 0.80), DHEAS (RR 0.98), and osteoporosis/osteopenia rate (RR 24.94) were also found to be independent influencing factors for HRT use.

CONCLUSIONS

A positive correlation between DHEAS levels and BMD was found in all three groups. Our study confirms earlier reports that DHEAS levels decrease with age in premenopausal and, especially, postmenopausal women regardless of estrogen treatment. DHEAS levels in postmenopausal women were not associated with atherogenic lipid patterns in the present study.

The effect of circulating androgens on bone mineral density in postmenopausal women

BACKGROUND

Osteoporosis is a common problem in postmenopausal period. Recent studies have suggested that endogenous and exogenous androgens may influence the bone mineral density in women. There is limited data about the effect of circulating androgens on bone density in postmenopausal women.

AIM

The aim of this study was to evaluate the effect of circulating androgens of ovarian and adrenal origin on bone mineral density in postmenopausal women.

MATERIALS AND METHODS

This cross-sectional study included 178 postmenopausal women, who had never been treated with hormonal therapy or calciotropic agents. Serum free testosterone, dehydroepiandrosterone sulfate and androstenedione levels and their relationship with bone mass (dual X-ray absorptiometry) were evaluated.

RESULTS

Serum free testosterone and DHEAS levels were correlated positively with bone mineral density at lumbar spine and femoral neck (P < 0.001). However, stepwise linear regression analyses revealed a differential effect of androgens on bone density. Serum free testosterone was among the independent predictor of bone density at lumbar spine (trabecular bone), whereas serum DHEAS level was of bone density at femoral neck (cortical bone).

CONCLUSION

This study suggests that endogenous androgens are influential on bone density in postmenopausal women. However, regression analyses revealed a differential effect of androgens on different bone types.

The role of estrogens in men and androgens in women

The past years several have witnessed a significant transformation in our understanding of sex steroid action in the male and female skeleton. Data from animal and human studies indicate that sex steroids have important skeletal effects in both genders. It seems from the in vivo human data that estrogen is likely more potent than testosterone in inhibiting bone resorption. Estrogen and testosterone appear to be important for maintaining bone formation. In addition, androgens clearly enhance bone size, likely through effects on periosteal bone formation. How much of this gender cross-talk at the physiological level is caused by "promiscuous" actions of sex steroids at the molecular level, with estrogen acting by way of the androgen receptor (and androgens via the estrogen receptor) is an interesting and important question, the answer to which may well provide additional surprises.

Dehydroepiandrosterone supplementation and bone turnover in middle-aged to elderly men

In the present placebo-controlled, double-blind study, we assessed the effect of dehydroepiandrosterone (DHEA) supplementation (90 mg orally/d) on bone turnover in 43 healthy men, 56-80 yr old. Placebo or steroid was given for 6 months, followed by a 1-month washout period and then a further 6 months of the opposite agent. Serum samples were collected at baseline 3, 6, 7, and 13 months and assayed for procollagen peptide, bone-specific alkaline phosphatase, and osteocalcin, all markers of bone formation. Measurements were also made of serum cortisol, DHEA/DHEA-S, E2 and free and total T. First void, fasting urine was collected at baseline, 6, 7, and 13 months and assessed for deoxypyridinoline, a marker of bone resorption. Mean serum DHEA and DHEA-S levels in treated men were increased approximately 3-fold ( approximately 2.2 ng/ml to approximately 6 ng/ml) and 4.5-fold ( approximately 1000 ng/ml to approximately 4500 ng/ml), respectively, after 6 months and returned to baseline after washout. Similarly, circulating E2 concentrations were also increased 1.4-fold (from approximately 16-23 pg/ml; P < 0.001), a finding not observed with any other measured hormone. Bone marker levels remained remarkably constant at each sampling interval; procollagen peptide at approximately 8.0 ng/ml; bone-specific alkaline phosphatase at approximately 21.0 U/liter; deoxypyridinoline at approximately 4.5 nmol/mmol Cr. Osteocalcin showed a transient reduction from approximately 10.2- 6.2 ng/ml, P < 0.005 to P < 0.001, at 3 months, but this decline was observed in both treated and controls. Stratifying the marker levels by age or baseline DHEA/DHEA-S levels did not affect the findings. We conclude that oral DHEA does not affect bone turnover in middle-aged to elderly men when used for a 6-month period at doses targeted to restore circulating levels of the steroid to that seen in young adults.

A primary adrenal steroid, 11beta-hydroxyandrostenedione, has an osteotropic effect and little androgenic activity

The physiological role of 11beta hydroxy-androstenedione (11betaOHA), a primary adrenal steroid, remains unknown. In the present study, we investigated the effect of 11betaOHA on bone metabolism in vitro and in vivo. Administration of 11betaOHA enhanced the clonal growth of marrow osteoprogenitor cells cultured from normal rats. In ovariectomized rats, 11betaOHA restored osteogenesis and increased the bone mineral density at both the metaphyseal and diaphyseal regions of the femur. Bone histomorphometric study of ovariectomized rats demonstrated that the mineral apposition rate of both cortical bone and trabecular bone was increased by treatment with 11betaOHA. In addition, 11betaOHA increased alkaline phosphatase activity in cultured osteoblastic cells (MC3T3-E1 and SaOS-2). The androgenic and anabolic effects of 11betaOHA were respectively estimated to be less than 1/100th and 1/10th-1/100th of those of testosterone, while the estrogenic action of 11betaOHA was also very weak. These findings suggest an influence of 11betaOHA on physiological bone metabolism and indicate that this steroid may be useful for stimulating of bone formation in the treatment of osteoporosis.

Serum estradiol and sex hormone-binding globulin and the risk of hip fracture in elderly women: the EPIDOS study

It has been suggested that low serum 17beta-estradiol (E2) and sex hormone-binding globulin (SHBG) may predict hip fracture in postmenopausal women. We have investigated the predictive value of serum E2 and SHBG concentrations and urinary deoxypyridinoline (D-Pyr) and type I collagen breakdown products (CTX) in a large prospective cohort of 7,598 healthy elderly ambulatory women (EPIDOS study), aged 75 years or more. We performed a nested case control study, by matching 212 patients with incident hip fracture with 636 controls. Mean follow-up was 3.3 years (maximum, 4.9 years). Women having serum E2 below the limit of detection (3 pg/ml), that is, 2% of the population, were not at higher risk, with a relative hazard (RH) of 1.59 (95% CI = 0.45-5.55). Women having serum E2 below 5, 6, 7, or 8 pg/ml, in the lowest quartile, or below the median had no increased risk of hip fracture. In contrast, women having serum E2 in the highest quartile (i.e., > or = 10 pg/ml) were protected, with an RH of 0.66 (0.44-0.98) that did not remain significant after adjustment for weight (RH = 0.71 [0.47-1.06]). High serum SHBG values with different cut-offs tended to be associated with an increased risk of hip fracture. Women in the highest quartile had an RH of 2.5 (1.37-4.61), compared with those in the lowest quartile, that decreased markedly after adjustment for body weight (1.61 [0.99 -2.62]). The highest quartile of the ratio E2/SHBG, which is an index of free E2, was associated with a lower hip fracture risk (RH = 0.6 [0.4-0.91]) that was no longer significant after adjustment for weight. In contrast, urinary D-Pyr and CTX, when elevated above the upper limit of premenopausal values, were predictive of hip fracture, with an RH of 2.07 (1.49-2.9) and 1.67 (1.19-2.32), respectively, even after adjustment for body weight, serum E2, and SHBG. We conclude that in healthy elderly French women over 75 years of age, serum E2 and E2/SHBG in the highest quartile are associated with a lower risk of hip fracture and that this association is explained by a higher body weight. In addition, serum levels of E2 and SHBG do not account for the increased risk of hip fracture associated with high levels of bone resorption markers.

Dehydroepiandrosterone (DHEA) and DHEA-S interact with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) to stimulate human osteoblastic cell differentiation

DHEA, an adrenocortical steroid, and its sulfate derivative (DHEA-S), have been implicated in many biological functions, including the regulation of bone mass. In this study, we examined whether DHEA/DHEA-S are capable of directly affecting bone cell proliferation and differentiation, and compared this with the effects of, and interaction with, the established bone cell modulating steroid, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Two in vitro models of human osteoblastic cells were used, viz. MG63 osteosarcoma cell line and normal primary osteoblast-like cells (HOB). Our results show that DHEA and DHEA-S failed on their own to exert direct, independent significant effects on the growth and differentiation of human osteoblastic cells, but treating the cells in conjunction with 1,25(OH)2D3 resulted in enhancement of specific A1P activity. Moreover, 1,25(OH)2D3-induced osteocalcin production was potentiated by the adrenal steroids in both cell models. DHEA-S proved in general to be more potent than DHEA. In conclusion, this study shows that the effects of DHEA/DHEA-S on osteoblastic cell growth and differentiation are likely to be mediated via an effect on 1,25(OH)2D3-induced changes in bone cells, suggesting a distinctive role for these steroids in the regulation of bone metabolism.

Effects of estrogen replacement therapy on dehydroepiandrosterone, dehydroepiandrosterone sulfate, and cortisol responses to exercise in postmenopausal women

OBJECTIVE

To determine the effects of hormone replacement therapy (HRT) on dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and cortisol (F) responses to treadmill exercise.

DESIGN

Controlled clinical study.

SETTING

Female volunteers in an academic research environment.

PATIENT(S)

Sixteen healthy, postmenopausal women (7 were receiving HRT, 9 were not).

INTERVENTION(S)

Blood samples were taken from an intravenous catheter before, during, and after 30 minutes of treadmill exercise following an overnight fast. A second session was conducted one month later for the same subjects using the same blood sampling protocol without exercise.

MAIN OUTCOME MEASURE(S)

Serum DHEA, DHEAS, and F concentrations.

RESULT(S)

The HRT and untreated DHEA area under the curve (AUC) for the exercise trials was significantly greater than that for the control trials. The untreated, but not the HRT, DHEAS AUC for the exercise trials was significantly greater than that for the control trials. The HRT and untreated F AUC for the exercise trials was significantly greater than that for the control trials. The AUC for the HRT exercise trials was significantly higher than the untreated exercise trials for DHEA and F, but not DHEAS.

CONCLUSION(S)

Data suggest that treadmill exercise elevates DHEA, DHEAS, and F levels in postmenopausal women and that HRT enhances the DHEA and F responses.

Endogenous sex steroids and bone mineral density in older women and men: the Rancho Bernardo Study

This study examines the associations between endogenous sex steroids and bone mineral density (BMD), using data from a geographically defined cohort in Rancho Bernardo, California. Participants were community-dwelling women and men aged 50-89 years who took part in a study of endogenous sex steroid measurement between 1984-1987 and who had BMD measured in 1988-1991. Those taking corticosteroids or estrogen at the time of sex steroid determination were excluded. The main study outcomes were BMD of the ultradistal radius, midshaft radius, lumbar spine, and total hip by sex steroid level, adjusted for age, body mass index, cigarette smoking, alcohol consumption, leisure exercise, use of thiazides, thyroid hormones, and former estrogen use (women only). At the time of the hormone measurements, the mean age of the 457 women was 72.1 years and that of the 534 men was 68.6 years. A statistically significant positive relation was seen between bioavailable estradiol and BMD at all sites in women and men. Total estradiol was significantly associated with BMD at all sites in women and at all but the ultradistal radius in men. Estrone had a global effect on BMD in women and was not measured in men. Higher bioavailable (but not total) testosterone levels were associated with higher BMD of the ultradistal radius, spine, and hip in men and the ultradistal radius in women. Dehydroepiandrosterone was positively associated with BMD of the midradius, spine, and hip in women and was not associated with BMD at any site in men. Of the sex steroids tested, bioavailable estrogen was most strongly associated with BMD in both women and men. We conclude that endogenous sex steroid levels are significantly related to bone density in older women and men. Individual variation in age-related bone loss may be partially accounted for by alterations in sex steroid levels with aging. Further study to elucidate safe environmental and medical methods to maintain optimal sex steroid levels in old age is needed.

Dehydroepiandrosterone (DHEA) and aging

Dehydroepiandrosterone sulfate (DHEAS) is the most abundant circulating steroid hormone in humans and can readily be converted to its parent steroid DHEA by tissue sulfatases. Yet, a biologic function for these steroids has not been defined. The link between DHEA and aging has been raised by: (1) its well documented age-related decline, and (2) a preventive effect of DHEA on numerous age-related illnesses: ischemic heart-disease, cognitive impairment, immunodeficiency, malignancies, osteoporosis. These effects have been suggested by epidemiological studies in humans. Animal studies support a protective effect of DHEA on these age-related diseases. However, it remains unknown whether these results in animals can be transposed in humans, because adrenal secretion of DHEA seems to be particular to primates. In humans, only a few studies have been performed. The effects of oral supplementation with DHEA have, so far, focused on the possible metabolic effects of DHEA. A few studies have shown: the absence of any side-effects; no change in body-weight; conflicting results on body-composition and lipids and no effect on insulin-tolerance. The latest study showed a beneficial effect on well-being but these results need to be confirmed.

Effect of dehydroepiandrosterone sulfate on carnitine acetyl transferase activity and L-carnitine levels in oophorectomized rats

Alteration in energy metabolism of postmenopausal women might be related to the reduction of dehydroepiandrosterone sulfate (DHEAS). DHEA and DHEAS decline with age, leveling at their nadir near menopause. DHEA and DHEAS modulate fatty acid metabolism by regulating carnitine acyltransferases and CoA. The purpose of this study was to determine whether dietary supplementation with DHEAS would also increase tissue L-carnitine levels, carnitine acetyltransferase (CAT) activity and mitochondrial respiration in oophorectomized rats. Plasma L-carnitine levels rose following oophorectomy in all groups (P < 0.0001). Supplementation with DHEAS was not associated with further elevation of plasma L-carnitine levels, but with increased hepatic total and free L-carnitine (P = 0.021 and P < 0.0001, respectively) and cardiac total L-carnitine concentrations (P = 0.045). In addition, DHEAS supplementation increased both hepatic and cardiac CAT activities (P < 0.0001 and P = 0.05 respectively). CAT activity positively correlated with the total and free carnitine levels in both liver and heart (r = 0.764, r = 0.785 and r = 0.700, r = 0.519, respectively). Liver mitochondrial respiratory control ratio, ADP:O ratio and oxygen uptake were similar in both control and supplemented groups. These results demonstrate that in oophorectomized rats, dietary DHEAS supplementation increases the liver and heart L-carnitine levels and CAT activities. In conclusion, DHEAS may modulate L-carnitine level and CAT activity in estrogen deficient rats. The potential role of DHEAS in the regulation of fatty acid oxidation in postmenopausal women is worthy of investigation.

Osteoporosis prevention and treatment with sex hormone replacement therapy

Oestrogen deficiency is by far the major factor contributing to the high rate of osteoporotic fractures in women. The anti-osteoporotic effect of estrogen may be explained by its property to regulate cytokine secretion and thus balance bone remodeling. In oestrogen deficiency, increased resorption and remodeling will occur leading to osteoporosis. It has been extensively shown that oestrogen replacement therapy (ERT) prevents postmenopausal bone loss and reduces fracture risk by half, provided that an appropriate dose is used. In order to optimize osteoporosis prevention, ERT should be started a early as possible in menopause and be maintained as long as possible. ERT may also be effective in elderly osteoporotic patients in preventing bone loss and, reducing fracture risk. The acceptance of ERT, however, at an older age has not been thoroughly evaluated. A reduction of cardiovascular disease and of climateric symptoms are among other benefits of ERT. So far, only few postmenopausal women are treated with ERT. ERT without progestins has been repeatedly found associated with an increased risk of developing endometrial cancer, but the cyclic addition of progestins protects from endometrial hyperplasia and carcinoma. Combined oestrogen-progestin therapy is as efficient as estrogen therapy alone, but not more so. Since progestins may oppose some of the beneficial effects of estrogens, the lowest dose with the least metabolic impact should be prescribed. Women who have had a hysterectomy, should probably be treated by estrogen replacement therapy only. Meta-analyses concerning breast cancer associated with ERT found a very moderately increased risk (RR = 1.06). Therefore ERT prescription should be discussed openly with women considering all risks and benefits. In women who have suffered from breast cancer, a bone sparing effect of tamoxifen has been shown.

Dehydroepiandrosterone sulphate and bone mineral density

Several series of data suggest that alterations in adrenal androgen output might be a contributing factor to changes in bone mass. To study the possible relationship between bone density and serum levels of dehydroepiandrosterone sulphate (DHEAS) we investigated 105 women (aged 45-69 years; 76 postmenopausal, 29 perimenopausal). The patients were divided into two groups according to the bone mineral density (BMD) measurement (normal density n = 50, low density n = 55). BMD was measured by dual-energy X-ray absorptiometry of the lumbar spine and femoral neck. Bone mineral content (BMC) of the radius midshaft was measured by single photon absorptiometry. Serum DHEAS level was significantly lower in the 'low density' group than in the 'normal' one (1.91 +/- 1.04 v 4.77 +/- 2.03 mumol/l, p < 0.001). The serum DHEAS level decreased significantly with age in both groups (r = 0.43, p < 0.001 in the 'normal' group; r = 0.35, p < 0.01 in the 'low density' group). Unlike the slopes, the positions of the regression lines differed significantly (difference 2.85 mumol/l, p < 0.001). Correcting for age by multiple linear regression we established a significant positive relationship between DHEAS and BMD of the lumbar spine and femoral neck, and BMC of radius midshaft as well. Since there was no significant difference between the two groups regarding oestrogens, we suggest that DHEAS may have a non-oestrogenic effect on bone. The odds ratio of a subject with a low (< 3.3 mumol/l) serum DHEAS level having low BMD was 40 (confidence interval 13-126).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of the climacteric on the bone mass of the spine and femur

OBJECTIVE

To determine the correlation between the bone mass of the lumbar spine and the neck of the femur in Spanish climacteric women.

METHOD

Bone mass was measured using quantitative digital radiology in 200 climacteric women who had no record of receiving hormone replacement therapy.

RESULT

A statistically significant correlation (P < 0.05) is observed between the bone mineral density and content of the lumbar spine and the femur in all the groups of climacteric women, although only in the postmenopausal women does it approach 70%. A direct relationship is observed between the loss of bone mass and the onset of the menopause, as well as with the patients' body mass index.

CONCLUSION

When the different parameters are analyzed, the results show that measurement of the lumbar spine is essential, and measurement of the femur should not be used as a substitute, but rather in addition to it.