Lack of evidence that progesterone in ovulatory cycles causes breast cancer.

A recent Perspective article asserted that progesterone secretion during ovulatory cycles is the cause of breast cancer. However, we challenge most of the evidence developed in this publication. First, there is a lack of evidence that progesterone is mutagenic for breast cells. Cause of a cancer should mean initiation by mutation, as opposed to promotion. Second, subclinical ovulatory disturbances occur rather frequently in normal-length menstrual cycles. Third, the authors attribute a potential carcinogenic effect to progesterone secreted during menstrual cycles but not to progesterone during pregnancy. They did not discuss breast cancer evidence from progesterone/progestin therapeutics. They argue that in genetic primary amenorrhea, a hypothetic lower risk of breast cancer could be due to the lack of progesterone, despite the progesterone/progestin in hormone replacements these women receive. Fourth, they advocate a regulatory effect of progesterone on several genes potentially involved in cancer genesis. In particular, they attribute a lower risk of breast cancer in women with Mayer-Rokitansky-Küster-Hauser syndrome to a defect in the progesterone-stimulated Wnt4 gene. However, this defect is only present in a small subset. Thus, the postulated progesterone breast cancer risk is unconvincing, which we discuss point by point in this commentary.

Simulated effects of early menopausal bone mineral density preservation on long-term fracture risk: a feasibility study.

Prevention of early menopausal bone loss may reduce the future burden of osteoporosis. In this modelling exercise, an osteoporosis prevention strategy involving 5-year infusions of zoledronic acid, beginning early in menopause, reduced long-term fracture risk and the proportion of aging women with femoral neck densitometric osteoporosis. This strategy warrants further evaluation. INTRODUCTION: Preventing early menopausal bone loss may substantially reduce the future burden of osteoporosis. We modelled the effects of infrequent zoledronic acid infusions on long-term fracture risk. METHODS: Data from the Canadian Multicentre Osteoporosis Study (CaMos) were used to determine the expected natural history of femoral neck areal bone mineral density (BMD) and fracture risk (using FRAX®) from ages 50-80 for women with no antiresorptive drug exposures. We modelled the effects of three infusions of zoledronic acid (at ages 50, 55, 60) on long-term fracture risk, assuming this intervention would preserve BMD until age 65 years, followed by losses mirroring early menopausal BMD loss. RESULTS: At age 65, untreated women and zoledronic acid recipients had expected mean (SD) femoral neck T-scores of - 1.5(1.0) and - 0.8(1.0), 10-year major osteoporotic fracture (MOF) risks of 9.8%(5.0) and 8.0%(3.7) and hip fracture risks of 1.7%(2.4) and 0.8%(1.2), respectively. At age 80, untreated women and zoledronic acid recipients had expected femoral neck T-scores of - 1.9(0.9) and - 1.4(0.9), MOF risks of 17.9%(8.2) and 14.9%(6.4) and hip fracture risks of 6.3%(6.2) and 4.4%(4.5), respectively. The expected proportion of women with femoral neck T-score ≤ - 2.5 was 14.9% for untreated women and 3.8% for zoledronic acid recipients at age 65, increasing to 28.1% and 12.0%, respectively, at age 80. Numbers-needed-to-treat to prevent one case of densitometric osteoporosis were 9 at age 65 and 5 at age 80. CONCLUSION: Infrequent infusions of zoledronic acid, initiated early in menopause, are expected to reduce long-term fracture risk and result in a substantial reduction in the proportion of women with densitometric osteoporosis after age 65.

Differences in fracture prevalence and in bone mineral density between Chinese and White Canadians: the Canadian Multicentre Osteoporosis Study (CaMos).

Fracture determinants differ between Canadians of Chinese and White descent, the former constituting the second largest visible minority group in Canada. The results of this study support the importance of characterizing bone health predictors in Canadians of different ethnicity to improve population-specific fracture prevention and treatment strategies. PURPOSE: We aimed to compare clinical risk factors, bone mineral density, prevalence of osteoporosis, and fractures between Chinese and White Canadians to identify ethnicity-specific risks. METHODS: We studied 236 Chinese and 8945 White Canadians aged 25+ years from the Canadian Multicentre Osteoporosis Study (CaMos). The prevalence of osteoporosis using ethnicity-specific peak bone mass (PBM), and of prior and incident low trauma fractures were assessed and compared between groups. Linear regressions, adjusting for age and anthropometric measures, were used to examine the association between baseline and 5-year changes in BMD and ethnicity. RESULTS: Chinese participants had shorter stature, lower BMI, and lower rate of falls than White participants. Adjusted models showed no significant differences in baseline BMD between ethnic groups except in younger men where total hip BMD was 0.059 g/cm2 (0.009; 0.108) lower in Chinese. Adjusted 5-year BMD change at lumbar spine was higher in older Chinese women and men compared with Whites. When using Chinese-specific PBM, the prevalence of osteoporosis in Chinese women was 2-fold lower than when using that of White women The prevalence of fractures was higher in White women compared with Chinese with differences up to 14.5% (95% CI 9.2; 19.7) and 10.5% (95% CI 4.5-16.4) in older White men. Incident fractures were rare in young Chinese compared with White participants and not different in the older groups. CONCLUSION: Our results support the importance of characterizing bone strength predictors in Chinese Canadians and the development of ethnicity-specific fracture prediction and prevention strategies.

Effects of progesterone therapy on serum sclerostin levels in healthy menopausal women: a 3-month randomized, placebo-controlled clinical trial.

Sclerostin, a natural hormone made in bone, suppresses bone formation. Sclerostin is also decreased by estrogen. Progesterone, estrogen's menstrual partner, stimulates bone formation. It is unclear whether progesterone influences sclerostin. This study showed that progesterone did not change sclerostin using serum remaining from a randomized progesterone hot flush therapy trial. INTRODUCTION: Progesterone and sclerostin are both endogenous hormones acting through osteoblast-origin cells and promote or suppress bone formation, respectively. Estradiol suppresses sclerostin, but progesterone, its menstrual cycle partner hormone, has unclear sclerostin relationships. We postulated that progesterone therapy would influence serum sclerostin levels. METHODS: We obtained sclerostin levels for an ethics-approved post hoc analysis. Fasting sclerostin was measured in all remaining sera from a previous 12-week randomized controlled trial (RCT) of oral micronized progesterone (progesterone) for menopausal (> 1 year after last flow) vasomotor symptoms (VMS). Women in the RCT took 300 mg progesterone at bedtime or placebo (1:1) in a trial showing progesterone significantly decreased VMS. RESULTS: Participants were healthy menopausal, primarily Caucasian (91.2%) community-dwelling women (± SD), 55.2 ± 4.6 years old with BMI 24.9 ± 2.9 kg/m2. The baseline sclerostin level in 60 women was 28.41 ± 10.47 pmol/L. Baseline sclerostin was not correlated with the run-in VMS score (r = 0.143, P = 0.294). Paired baseline and 12-week RCT data for 52 women showed serum sclerostin levels did not change related to experimental therapy (P = 0.504). Changes in final sclerostin values adjusted for baseline were progesterone (- 1.07 ± 7.96 pmol/L) and placebo (- 2.64 ± 8.70 pmol/L). In observational data (n = 60), baseline sclerostin levels correlated with the General Framingham Cardiovascular (CVD) Risk score (r = - 0.398, P = 0.003) and self-reported health by SF-36 quality of life instrument (QoL, r = - 0.331, P = 0.016). CONCLUSION: Physiological oral micronized progesterone did not stimulate nor suppress serum sclerostin levels based on post hoc analysis of RCT data. Exploratory results, however, showed sclerostin negatively correlated with CVD risk and QoL. ClinicalTrials.gov #NCT0146469.

Testing a theoretical model of imminent fracture risk in elderly women: an observational cohort analysis of the Canadian Multicentre Osteoporosis Study.

We examined the underlying relationship between fracture risk factors and their imminent risk. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher imminent fracture risk. Past year falls indirectly predicted imminent risk through physical functioning and general health. INTRODUCTION: This study aimed to examine direct and indirect effects of several factors on imminent (1 year) fracture risk. METHODS: Data from women age 65 and older from population-based Canadian Multicentre Osteoporosis Study were used. Predictors were identified from study years 5 and 10, and imminent fracture data (1-year fracture) came from years 6 and 11 (year 5 predicts year 6, year 10 predicts year 11). A structural equation model (SEM) was used to test the theoretical construct. General health and physical functioning were measured as latent variables using items from the 36-Item Short Form Health Survey (SF-36) and bone mineral density (BMD) T-score was a latent variable based on observed site-specific BMD data (spine L1-L4, femoral neck, total hip). Observed variables were fractures and falls. Model fit was evaluated using root mean square error of approximation (RMSEA), Tucker Lewis index (TLI), and comparative fit index (CFI). RESULTS: The analysis included 3298 women. Model fit tests showed that the SEM fit the data well; χ2(172) = 1122.10 < .001, RMSEA = .03, TLI = .99, CFI = .99. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher risk of fracture in the subsequent year (p < .001). Past year falls had a statistically significant but indirect effect on imminent fracture risk through physical functioning and general health (p < .001). CONCLUSIONS: We found several direct and indirect pathways that predicted imminent fracture risk in elderly women. Future studies should extend this work by developing risk scoring methods and defining imminent risk thresholds.

Longitudinal assessment of health-related quality of life in osteoporosis: data from the population-based Canadian Multicentre Osteoporosis Study.

Little is known about the association between health-related quality of life (HRQOL) and osteoporosis in the absence of fracture, and how HRQOL may change over time. This study provides evidence of substantially reduced HRQOL in women and men with self-reported and/or BMD-confirmed osteoporosis, even in the absence of fragility fracture. INTRODUCTION: Fragility fractures have a detrimental effect on the health-related quality of life (HRQOL) of those with osteoporosis. Less is known about the association between HRQOL and osteoporosis in the absence of fracture. METHODS: Canadian Multicentre Osteoporosis Study participants completed the SF-36, a detailed health questionnaire and measures of bone mineral density (BMD) at baseline and follow-up. We report the results of participants ≥ 50 years with 10-year follow-up. Self-reported osteoporosis at baseline and BMD-based osteoporosis at follow-up were ascertained. Multivariable linear regression models were developed for baseline SF-36 domains, component summaries, and change over time, adjusting for relevant baseline information. RESULTS: Baseline data were available for 5266 women and 2112 men. Women in the osteoporosis group had substantially lower SF-36 baseline scores, particularly in the physically oriented domains, than those without osteoporosis. A similar but attenuated pattern was evident for the men. After 10-year follow-up (2797 women and 1023 men), most domain scores dropped for women and men regardless of osteoporosis status, with the exception of mentally-oriented ones. In general, a fragility fracture was associated with lower SF-36 scores and larger declines over time. CONCLUSIONS: This study provides evidence of substantially reduced HRQOL in women and men with self-reported and/or BMD-confirmed osteoporosis, even in the absence of fragility fracture. HRQOL should be thoroughly investigated even prior to fracture, to develop appropriate interventions for all stages of the disease.

Mortality risk reduction differs according to bisphosphonate class: a 15-year observational study.

In this prospective cohort of 6120 participants aged 50+, nitrogen-bisphosphonates but not non-nitrogen bisphosphonates were associated with a significant 34% mortality risk reduction compared to non-treated propensity score matched controls. These findings open new avenues for research into mechanistic pathways. INTRODUCTION: Emerging evidence suggests that bisphosphonates (BP), first-line treatment of osteoporosis, are associated with reduced risks for all-cause mortality. This study aimed to determine the association between different BP types and mortality risk in participants with or without a fracture. METHODS: A prospective cohort study of users of different BPs matched to non-users by propensity score (age, gender, co-morbidities, fragility fracture status) and time to starting the BP medication from the population-based Canadian Multicentre Osteoporosis Study from nine Canadian centres followed from 1995 to 2013. Mortality risk for bisphosphonate users vs matched non-users was assessed using pairwise multivariable Cox proportional hazards models. RESULTS: There were 2048 women and 308 men on BP and 1970 women and 1794 men who did not receive medication for osteoporosis. The relationship between BP and mortality risk was explored in three separate 1:1 propensity score-matched cohorts of BP users and no treatment (etidronate, n = 599, alendronate, n = 498, and risedronate n = 213). Nitrogen BP (n-BP) (alendronate and risedronate) was associated with lower mortality risks [pairwise HR, 0.66 (95% CI, 0.48-0.91)] while the less potent non-n-BP, etidronate, was not [pairwise HR: 0.89 (95% CI, 0.66-1.20)]. A direct comparison between n-BP and etidronate (n = 340 pairs) also suggested a better survival for n-BP [paired HR, 0.47 (95%CI, (95% CI, 031-0.70)] for n-BP vs. etidronate]. CONCLUSION: Compared to no treatment, nitrogen but not non-nitrogen bisphosphonates appear to be associated with better survival.

Progesterone for treatment of symptomatic menopausal women.

This review's purpose is to highlight evidence that oral micronized progesterone (progesterone) is effective for hot flushes and night sweats (vasomotor symptoms, VMS), improves sleep and is likely safe in menopausal women (who are more than 1 year since last menstruation). Methods include randomized controlled clinical trials (RCT) supplemented with basic science, population and observational data as needed. The barrier to use of progesterone is lack of awareness that safety concerns with estrogen-including 'menopausal hormone therapy' (MHT) are not applicable to progesterone. In a single 3-month RCT, progesterone (300 mg at bedtime) was effective treatment of VMS in 133 healthy menopausal women. It caused an overall 55% VMS decrease, no withdrawal-related VMS rebound and a greater VMS decrease in 46 women with ≥50 moderate-intense VMS/week. Progesterone is equally or more effective than estradiol in improving cardiovascular endothelial function and caused no cardiovascular safety concerns in a 3-month RCT. An 8-year prospective cohort study (E3N) in more than 80 000 menopausal women showed progesterone prevented breast cancer in estrogen-treated women. Multiple RCTs confirm that progesterone (300 mg daily at bedtime) does not cause depression and improves deep sleep. In conclusion, progesterone effectively treats VMS, improves sleep and may be the only therapy that symptomatic women, who are menopausal at a normal age and without osteoporosis, need.

Progesterone for the prevention and treatment of osteoporosis in women.

Estradiol (E2) is women's dominant 'bone hormone' since it is essential for development of adolescent peak bone mineral density (BMD) and physiological levels prevent the rapid (3-week) bone resorption that causes most adult BMD loss. However, deceasing E2 levels trigger bone resorption/loss. Progesterone (P4) is E2's physiological partner, collaborating with E2 in every cell/tissue; its bone 'job' is to increase P4-receptor-mediated, slow (3-4 months) osteoblastic new bone formation. When menstrual cycles are normal length and normally ovulatory, E2 and P4 are balanced and BMD is stable. However, clinically normal cycles commonly have ovulatory disturbances (anovulation, short luteal phases) and low P4 levels; these are more frequent in teen and perimenopausal women and increased by everyday stressors: energy insufficiency, emotional/social/economic threats and illness. Meta-analysis shows that almost 1%/year spinal BMD loss occurs in those with greater than median (∼31%) of ovulatory disturbed cycles. Prevention of osteoporosis and fragility fractures requires the reversal of stressors, detection and treatment of teen-to-perimenopausal recurrent cycle/ovulatory disturbances with cyclic oral micronized progesterone. Low 'Peak Perimenopausal BMD' is likely the primary risk for fragility fractures in later life. Progesterone plus estradiol or other antiresorptive therapies adds 0.68%/year and may be a highly effective osteoporosis treatment. Randomized controlled trials are still needed to confirm progesterone's important role in women's bone formation.

Estrogen-progestin therapy causes a greater increase in spinal bone mineral density than estrogen therapy - a systematic review and meta-analysis of controlled trials with direct randomization.

OBJECTIVE: To assess whether progesterone (P4) or osteoblast P4 receptor-acting progestin (P) contributed to estrogen (E) therapy-related increased areal bone mineral density (BMD) in randomized controlled trials (RCT) with direct randomization to estrogen (ET) or estrogen-progestin (EPT) therapy. METHODS: Systematic literature searches in biomedical databases identified RCT with direct randomization and parallel estrogen doses that measured spinal BMD change/year. Cyclic P4/P was included in this random effects meta-analysis only if for ≥ half the number of E-days. RESULTS: Searches yielded 155 publications; five met inclusion criteria providing eight dose-parallel ET-EPT comparisons in 1058 women. Women averaged mid-50 years, ⟨five years into menopause and took conjugated equine E daily at 0.625 mg with/without 2.5 mg medroxyprogesterone acetate (MPA). The weighted mean EPT minus ET percentage difference in spinal BMD change was +0.68%/year (95% CI 0.38, 0.97%) (P=0.00001). This result was highly heterogeneous (I²=81%) but this may reflect the small number of studies. CONCLUSION: Estrogen with an osteoblast P4R-acting progestin (EPT) in these five published RCT provides Level 1 evidence that MPA caused significantly greater annual percent spinal BMD gains than the same dose of ET. These data have implications for management of vasomotor symptoms and potentially for osteoporosis treatment in menopausal women.

Premenopausal Trabecular Bone Loss is Associated with a Family History of Fragility Fracture.

INTRODUCTION: Although a fragility fracture family history (FFFH+) has repeatedly been shown to be associated with lower bone mineral density (BMD), its relationship to human BMD change is unclear. Animal research, however, documented that different purebred strains within rodent species have wide ranges in rates of bone acquisition during growth as well as in change post-ovariectomy. Our objective was to compare the rate of premenopausal spinal trabecular BMD change between women with and without a general family history of fragility fracture. PARTICIPANTS AND METHODS: Healthy premenopausal community women participated in prospective observational studies at two academic medical research centres: Vancouver, Canada (n = 66) and Munich, Germany (n = 20). The primary outcome was annual spinal BMD change, measured by quantitative computed tomography (QCT). The two studies employed similar methodologies for assessing QCT and FFFH. RESULTS: Volunteer community participants had a mean age of 36.0 (SD, 6.9) years, body mass index 22.5 (2.4) and baseline QCT of 150.2 (22.5) mg/cm3 trabecular bone. The rates of BMD change were similar in both cities: - 3.5 (5.1)/year Vancouver, - 2.0 (3.4)/year Munich (95 % CI of difference: - 3.9, 0.9). Over a third of the women (31 of the 86, 36 %) reported FFFH+. Those with and without a FFFH were similar in demographics, nutrition, exercise, menstrual cycle and luteal phase lengths and physiological measures (serum calcium, osteocalcin and estradiol). However, women with FFFH+ lost trabecular BMD more rapidly: FFFH+, - 4.9 (5.0), FFFH-, - 2.2 (4.4) mg/cm3/year (95 % CI diff - 0.7 to - 4.8, F1.83 = 7.88, p = 0.006). FFFH+ explained 7.7 % of the variance in QCT volumetric trabecular spinal bone change/year in these healthy premenopausal women. CONCLUSION: This study shows for the first time that having a history of a fragility fracture in a family member is associated with a greater rate of premenopausal spinal trabecular bone loss.

Associations of Protein Intake and Protein Source with Bone Mineral Density and Fracture Risk: A Population-Based Cohort Study.

UNLABELLED: High dietary protein has been hypothesized to cause lower bone mineral density (BMD) and greater fracture risk. Previous results are conflicting and few studies have assessed potential differences related to differing protein sources. OBJECTIVE: To determine associations between total protein intake, and protein intake by source (dairy, non-dairy animal, plant) with BMD, BMD change, and incident osteoporotic fracture. DESIGN/SETTING: Prospective cohort study (Canadian Multicentre Osteoporosis Study). Participants/Measures: Protein intake was assessed as percent of total energy intake (TEI) at Year 2 (1997-99) using a food frequency questionnaire (N=6510). Participants were contacted annually to ascertain incident fracture. Total hip and lumbar spine BMD was measured at baseline and Year 5. Analyses were stratified by group (men 25-49 y, men 50+ y, premenopausal women 25-49 y, and postmenopausal women 50+ y) and adjusted for major confounders. Fracture analyses were limited to those 50+ y. RESULTS: Intakes of dairy protein (with adjustment for BMI) were positively associated with total hip BMD among men and women aged 50+ y, and in men aged 25-49. Among adults aged 50+ y, those with protein intakes of <12% TEI (women) and <11% TEI (men) had increased fracture risk compared to those with intakes of 15% TEI. Fracture risk did not significantly change as intake increased above 15% TEI, and was not significantly associated with protein source. CONCLUSIONS: In contrast to hypothesized risk of high protein, we found that for adults 50+ y, low protein intake (below 15% TEI) may lead to increased fracture risk. Source of protein was a determinant of BMD, but not fracture risk.

Characteristics of hyperparathyroid states in the Canadian multicentre osteoporosis study (CaMos) and relationship to skeletal markers.

CONTEXT: PTH is an essential regulator of mineral metabolism; PTH hypersecretion may result in hyperparathyroidism including normocalcaemic, primary and secondary hyperparathyroidism. OBJECTIVE: To examine the characteristics of participants with hyperparathyroid states and the relationship to bone mineral density (BMD). DESIGN AND PARTICIPANTS: A cross-sectional study of 1872 community-dwelling men and women aged 35+ years (mostly Caucasian) with available serum PTH from Year 10 Canadian Multicentre Osteoporosis Study follow-up (2005-07). PTH was determined using a second-generation chemiluminescence immunoassay. OUTCOME MEASURES: L1-L4, femoral neck and total hip BMD. RESULTS: We established a PTH reference range (2·7-10·2 pmol/l) based on healthy participants (i.e. normal serum calcium, serum 25-hydroxyvitamin D, kidney function and body mass index, who were nonusers of antiresorptives, glucocorticoids and diuretics and not diagnosed with diabetes or thyroid disease). Participants with PTH levels in the upper reference range (5·6-10·2 pmol/l), representing a prevalence of 10·7%, had lower femoral neck and total hip BMD, by 0·030 g/cm(2) [95% confidence interval: 0·009; 0·051] and 0·025 g/cm(2) (0·001; 0·049), respectively, than those with levels 2·7-5·6 pmol/l. Participants with normocalcaemic and secondary hyperparathyroidism also had lower total hip BMD than those with levels 2·7-5·6 pmol/l, and CaMos prevalences of normocalcaemic, primary and secondary hyperparathyroidism were 3·3%, 1·4% and 5·2%, respectively. CONCLUSION: We found reduced BMD in participants with accepted hyperparathyroid states but also a notable proportion of other participants that might benefit from having lower PTH levels.

Longitudinal changes in calcium and vitamin D intakes and relationship to bone mineral density in a prospective population-based study: the Canadian Multicentre Osteoporosis Study (CaMos).

OBJECTIVES: Our objective was to study changes in calcium and vitamin D intakes over time, and their cross-sectional and longitudinal associations with bone mineral density (BMD). METHODS: We followed 9382 women and men aged ≥25 and 899 aged 16-24, for 10 and 2 years respectively. RESULTS: Calcium and vitamin D intakes increased over time in adults, but decreased in women aged 16-18. The increased intakes in adults were largely attributable to the increased use of calcium and/or vitamin D supplements. Both the percentage of supplement users and average dose among users increased over time. There was nevertheless a high prevalence of calcium and vitamin D intake below the estimated average requirement. At baseline, higher calcium and vitamin D intakes were associated with higher total hip and femoral neck BMD in young men, and cumulatively high levels of calcium and vitamin D intakes over time contributed to better BMD maintenance at lumbar spine and hip sites in adult women. CONCLUSIONS: Although total intakes, particularly of vitamin D, frequently fell below the Institute of Medicine recommendations despite an increase over time in supplement use, we found some positive associations between total calcium and vitamin D intake and bone health.

Progesterone therapy increases free thyroxine levels--data from a randomized placebo-controlled 12-week hot flush trial.

OBJECTIVE: Thyroid hormones and progesterone both influence core temperature, metabolism and are crucial during pregnancy. Our objective was to discover whether progesterone therapy caused changes in thyroid physiology compared with placebo. DESIGN: Post hoc analysis from a randomized (1:1) placebo-controlled 12-week trial of oral micronized progesterone (Progesterone, 300 mg/d at bedtime) for hot flushes (vasomotor symptoms, VMS) conducted in an academic medical centre. PATIENTS: Postmenopausal euthyroid, healthy (without cardiovascular diseases or risks) women, 1-11 years since last flow on no thyroid or ovarian hormone therapy with VMS participated. MEASUREMENTS: Primary outcomes were final and 12-week changes in TSH, FreeT3 and FreeT4 on progesterone vs placebo. RESULTS: Women with thyroid data (69 of 133 in original trial) were randomized to progesterone (n = 39) or placebo (n = 30)-baseline thyroid values were normal. There were no VMS-thyroid interactions-VMS Score (number × intensity) did not correlate with TSH, FreeT3 or FreeT4 (Spearman's rank correlations: -0.03 to -0.19, respectively; all P > 0.15). At 12 weeks on progesterone, TSH levels tended to be lower (1.7 mU) than on placebo (2.2), P = 0.06; FreeT4 levels were higher (16.4 pmol/l) than on placebo (15.3), P = 0.02. FreeT3 was unchanged throughout. Analysis of covariance showed a significant increase in FreeT4 on progesterone (+2.5 pmol/l; 1.9-3.0) vs on placebo (+1.7; 1.1-2.4) with 95% CI of difference = 0.8 pmol/l [0.0, 1.6], P = 0.04. CONCLUSIONS: Progesterone caused a significant FreeT4 increase that was discovered during this randomized controlled VMS trial. The clinical importance of this increased FreeT4 level remains to be documented. Registered at ClinialTrials.gov#NCT00152438.

Predicting fracture using 2D finite element modelling.

A decrease in bone density at the hip or spine has been shown to increase the risk of fracture. A limitation of the bone mineral density (BMD) measurement is that it provides only a measure of a bone sample's average density when projected onto a 2D surface. Effectively, what determines bone fracture is whether an applied load exceeds ultimate strength, with both bone tissue material properties (can be approximated through bone density), and geometry playing a role. The goal of this project was to use bone geometry and BMD obtained from radiographs and DXA measurements respectively to estimate fracture risk, using a two-dimensional finite element model (FEM) of the sagittal plane of lumbar vertebrae. The Canadian Multicentre Osteoporosis Study (CaMos) data was used for this study. There were 4194 men and women over the age of 50 years, with 786 having fractures. Each subject had BMD testing and radiographs of their lumbar vertebrae. A single two dimensional FEM of the first to fourth lumbar vertebra was automatically generated for each subject. Bone tissue stiffness was assigned based on the BMD of the individual vertebrae, and adjusted for patient age. Axial compression boundary conditions were applied with a force proportional to body mass. The resulting overall strain from the applied force was found. Men and women were analyzed separately. At baseline, the sensitivity of BMD to predict fragility fractures in women and men was 3.77% and 0.86%, while the sensitivity of FEM to predict fragility fractures for women and men was 10.8% and 11.3%. The FEM ROC curve demonstrated better performance compared to BMD. The relative risk of being considered at high fracture risk using FEM at baseline, was a better predictor of 5 year incident fragility fracture risk compared to BMD.