Hormone replacement therapy, renal function and heart ultrasonographic parameters in postmenopausal women: an observational study

Glomerular filtration rate and sexual dimorphism: lessons from animal and human studies

PURPOSE OF REVIEW

Integrating sex-based analyses is becoming a key point in the new recommendations, particularly in nephrology.

RECENT FINDINGS

Whereas single nephron glomerular filtration rate (GFR) is not different between men and women, male sex is associated, after multiple adjustments, with a higher number of nephrons. However, after indexation to body surface area, measured GFR (mGFR) in healthy potential kidney donors is not different between men and women between 20 and 50 years of age. After 50 years, mGFR decline seems faster in women than in men, which is concordant with the protective role of estrogens on renal function, as demonstrated in animal and some human studies. Conversely, testosterone has a detrimental effect on renal function. Of note, although testosterone has been shown to increase the kidney volume of the remnant kidney after a unilateral nephrectomy in animal models, this may generate deleterious hyperfiltration in the longer term.

SUMMARY

Taken together, these data highlight the impact of sex on GFR, notably through sexual hormones whose receptors are expressed in glomerular cells.

Association between estrogen and kidney function: population based evidence and mutual bidirectional Mendelian randomization study

BACKGROUND

Previous studies have suggested a potential role of estrogen in the pathophysiology of chronic kidney disease (CKD); however, the association and causality between estrogen and kidney function remain unclear.

METHODS

The cross-sectional correlation between serum estradiol concentration and estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR) was analyzed using data from the National Health and Nutrition Examination Survey 2013-2016. Causality was tested using mutual bidirectional Mendelian randomization (MR) approaches based on six large-scale GWAS studies. Weighted generalized multivariate linear regression was employed to estimate the association between estradiol and eGFR and ACR, and a restricted cubic spline analysis was utilized to investigate potential nonlinear relationships.

RESULTS

A total of 8932 participants were included. Serum estradiol concentration was positively associated with eGFR after adjusting for potential covariates (β, 0.76; 95% CI 0.24 to 1.27) and with ACR (β, 5.99; 95% CI 1.62 to 10.36). A nonlinear positive association was found between estradiol and eGFR, while an inverse "V"-shaped relationship was seen with ACR. Sensitivity analyses confirmed the stability of the relationship between estradiol and eGFR but indicated a less robust association with ACR. Stratified analysis showed that the association between estradiol and eGFR was particularly significant in populations with CKD and hypertension. All forward MR analyses demonstrated a positive causal relationship between estradiol and eGFR, but no causality was found between estradiol and ACR. No reverse causal association was observed.

CONCLUSIONS

Serum estradiol concentration was causally associated with eGFR. Further longitudinal research is needed to validate these findings.

Menopause is associated with a reduction in glomerular filtration rate, independent of body composition and metabolic syndrome

OBJECTIVES

This study examines the relationship between menopause and glomerular filtration rate (GFR), independent of body composition and metabolic profile, both known risk factors for GFR decline.

STUDY DESIGN

Cross-sectional study involving 3918 women aged 40-55 years.

MAIN OUTCOME MEASURES

Participants provided information about medical history, menopausal status, and current medication use. Participants underwent nutritional and anthropometric assessments. Blood samples were collected to measure biochemical parameters. Menopause was defined as no menstrual cycle for 12 months or more. GFR was estimated using the EPI-CKD formula, and metabolic syndrome was identified using harmonized criteria. Premenopausal and postmenopausal women were matched by age, body composition, and metabolic syndrome factors to assess the menopause-GFR association.

RESULTS

Postmenopausal women exhibited higher fat mass, lower fat-free mass, and reduced GFR compared with premenopausal women. They also had higher rates of hypertension, impaired fasting glucose, and metabolic syndrome. After matching for age, fat mass index, fat-free mass index, and components of the metabolic syndrome, menopause was independently associated with a GFR reduction of 2.32 ml/min/1.73m2 (95 % CI: -3.81, -0.83). Additionally, menopause was linked to a 51 % higher risk of GFR <90 ml/min/1.73m2 (OR = 1.51; 95 % CI 1.12, 2.02).

CONCLUSIONS

Menopause represents an independent risk factor for GFR decline, beyond the effects related to body composition and metabolic risk factors.

Factors Contributing to Coronary Microvascular Dysfunction in Patients with Angina and Non-Obstructive Coronary Artery Disease

BACKGROUND

Coronary microvascular dysfunction (CMD), characterised by a reduced coronary flow reserve (CFR) or an increased index of microcirculatory resistance (IMR), has received considerable attention as a cause of chest pain in recent years. However, the risks and causes of CMD remain unclear; therefore, effective treatment strategies have not yet been established. Heart failure or coronary artery disease (CAD) is a risk factor for CMD, with a higher prevalence among women. However, the other contributing factors remain unclear. In this study, we assessed the risk in patients with angina and non-obstructive coronary artery disease (ANOCA), excluding those with heart failure or organic stenosis of the coronary arteries. Furthermore, we analysed whether the risk of CMD differed according to component factors and sex.

METHODS

This study included 84 patients with ANOCA (36 men and 48 women; mean age, 63 years) who underwent coronary angiography and functional testing (CFT). The CFT included a spasm provocation test (SPT), followed by a coronary microvascular function test (CMVF). In the SPT, patients were mainly provoked by acetylcholine (ACh), and coronary spasm was defined as >90% transient coronary artery constriction on coronary angiography, accompanied by chest pain or ischaemic changes on electrocardiography. In 15 patients (18%) with negative ACh provocation, ergonovine maleate (EM) was administered as an additional provocative drug. In the CMVF, a pressure wire was inserted into the left anterior descending coronary artery using intravenous adenosine triphosphate, and the CFR and IMR were measured using previously described methods. A CFR < 2.0 or IMR ≥ 25 was indicative of CMD. The correlations between various laboratory indices and CMD and its components were investigated, and logistic regression analysis was performed, focusing on factors where p < 0.05.

RESULTS

Of the 84 patients, a CFR < 2.0 was found in 22 (26%) and an IMR ≥ 25 in 40 (48%) patients, with CMD identified in 46 (55%) patients. CMD was correlated with smoking (p = 0.020) and the use of EM (p = 0.020). The factors that correlated with a CFR < 2.0 included the echocardiograph index E/e' (p = 0.013), which showed a weak but positive correlation with the CFR (r = 0.268, p = 0.013). Conversely, the factors correlated with an IMR ≥ 25 included RAS inhibitor usage (p = 0.018) and smoking (p = 0.042). Assessment of the risk of CMD according to sex revealed that smoking (p = 0.036) was the only factor associated with CMD in men, whereas the left ventricular mass index (p = 0.010) and low glycated haemoglobin levels (p = 0.012) were associated with CMD in women.

CONCLUSIONS

Our results indicated that smoking status and EM use were associated with CMD. The risk of CMD differed between the two CMD components and sex. Although these factors should be considered when treating CMD, smoking cessation remains important. In addition, CMD assessment should be performed carefully when EM is used after ACh provocation. Further validation of our findings using prospective studies and large registries is warranted.

Cardiac Mechanics in Altered Hormonal States as a Surrogate for Understanding the Effects of Transgender Hormone Therapy

Transgender individuals are increasingly seeking the care of physicians to physically transition to their self-identified gender identity. Gender-affirming hormone therapy (GAHT) has significant endocrine effects which may have cardiovascular consequences, and cardiovascular disease in transgender individuals is a growing area of study. The effects of GAHT on cardiac mechanics have yet to be characterized, but there is existing literature regarding changes to cardiac mechanics in similar altered hormonal states. We reviewed this literature, with a focus on echocardiographic findings. We found variable results between studies of different methodologies. These include findings that supraphysiological levels of testosterone may impair cardiac mechanics, whereas estrogen-containing hormonal replacement therapy may improve diastolic echocardiographic parameters. In summary, there are alterations to echocardiographic parameters in altered endocrine states related to exogenous testosterone and estrogen, in a manner that is likely dose-dependent. Encouragingly, the studies we reviewed did not suggest that hormonal changes within physiologic ranges would detrimentally affect echocardiographic parameters of systolic and diastolic function. Future research into the cardiovascular effects of long-term GAHT is warranted to safely guide the longitudinal treatment of transgender individuals.

Attributable risks of hospitalizations for urologic diseases due to heat exposure in Queensland, Australia, 1995-2016

BACKGROUND

Heat exposure is a risk factor for urologic diseases. However, there are limited existing studies that have examined the relationship between high temperatures and urologic disease. The aim of this study was to examine the associations between heat exposure and hospitalizations for urologic diseases in Queensland, Australia, during the hot seasons of 1995-2016 and to quantify the attributable risks.

METHODS

We obtained 238 427 hospitalized cases with urologic diseases from Queensland Health between 1 December 1995 and 31 December 2016. Meteorological data were collected from the Scientific Information for Land Owners-a publicly accessible database of Australian climate data that provides daily data sets for a range of climate variables. A time-stratified, case-crossover design fitted with the conditional quasi-Poisson regression model was used to estimate the associations between temperature and hospitalizations for urologic diseases at the postcode level during each hot season (December-March). Attributable rates of hospitalizations for urologic disease due to heat exposure were calculated. Stratified analyses were performed by age, sex, climate zone, socio-economic factors and cause-specific urologic diseases.

RESULTS

We found that a 1°C increase in temperature was associated with a 3.3% [95% confidence interval (CI): 2.9%, 3.7%] increase in hospitalization for the selected urologic diseases during the hot season. Hospitalizations for renal failure showed the strongest increase 5.88% (95% CI: 5.25%, 6.51%) among the specific causes of hospital admissions considered. Males and the elderly (≥60 years old) showed stronger associations with heat exposure than females and younger groups. The sex- and age-specific associations with heat exposure were similar across specific causes of urologic diseases. Overall, nearly one-fifth of hospitalizations for urologic diseases were attributable to heat exposure in Queensland.

CONCLUSIONS

Heat exposure is associated with increased hospitalizations for urologic disease in Queensland during the hot season. This finding reinforces the pressing need for dedicated public health-promotion campaigns that target susceptible populations, especially for those more predisposed to renal failure. Given that short-term climate projections identify an increase in the frequency, duration and intensity of heatwaves, this public health advisory will be of increasing urgency in coming years.

High Circulating Follicle-Stimulating Hormone Level Is a Potential Risk Factor for Renal Dysfunction in Post-Menopausal Women

OBJECTIVE

Menopause contributes to renal dysfunction in women, which is generally attributed to estrogen withdrawal. In addition to decreased estrogen level, serum follicle-stimulating hormone (FSH) level increases after menopause. This study investigated the association between high circulating FSH level and renal function in post-menopausal women.

METHODS

This observational cross-sectional study included 624 pre-menopausal, 121 peri-menopausal, and 2540 post-menopausal women. The levels of female sex hormones were examined by chemiluminescence and indices of renal function were measured using a clinical chemistry analyzer. The post-menopausal women were grouped into quartiles according to serum FSH levels.

RESULTS

Renal function progressively declined from pre-menopause to peri-menopause to post-menopause, which was accompanied by increasing serum FSH level. In post-menopausal women, serum creatinine level increased with increasing FSH quartile, which was accompanied by a decrease in estimated glomerular filtration rate (eGFR) (p for trend <0.001); moreover, the prevalence of declined eGFR (<90 ml/min/1.73 m²) and chronic kidney disease (CKD; eGFR <60 ml/min/1.73 m²) increased (p for trend <0.001). Even after adjusting for confounders, the odds ratios (ORs) of declined eGFR and CKD increased with increasing FSH quartiles in post-menopausal women. The ORs of declined eGFR (OR=2.19, 95% confidence interval [CI]: 1.63-2.92) and CKD (OR=10.09, 95% CI: 2.28-44.65) in the highest FSH quartile were approximately 2- and 10-fold higher, respectively, than in the lowest FSH quartile (p<0.05). After stratifying post-menopausal women by median age (61 years), the OR for declined eGFR for each FSH quartile in the older group was higher than that for the corresponding FSH quartile in the younger group.

CONCLUSIONS

A high circulating FSH level is an independent risk factor for renal dysfunction in women after menopause. Additionally, aging may aggravate the association of high FSH levels with reduced renal function in post-menopausal women.

Hormone therapy and urine protein excretion: a multiracial cohort study, systematic review, and meta-analysis

OBJECTIVE

Experimental models suggest estrogen has a renoprotective effect, but human studies show variable results. Our objective was to study the association of hormone therapy (HT) and albuminuria in postmenopausal women and to synthesize the results with outcomes from prior studies.

METHODS

We analyzed data from postmenopausal women who participated in the second study visit (2000-2004) of the Genetic Epidemiology Network of Arteriopathy (GENOA) study. The exposure was self-reported HT use and the outcome was albuminuria (urine albumin-to-creatinine ratio >25 mg/g creatinine). We also conducted a systematic review and meta-analysis on the association of HT and urine protein in postmenopausal women. Continuous and dichotomous measures of protein excretion were converted to a standardized mean difference (SMD) for each study.

RESULTS

In the GENOA cohort (n = 2,217), there were fewer women with albuminuria among HT users than nonusers (9% vs 19%, P < 0.001). HT use was associated with decreased odds of albuminuria (odds ratio 0.65, 95% confidence interval (CI), 0.45-0.95), after adjusting for significant differences in age, race, education, comorbidities, and the age at and cause of menopause. The SMD of the effect of HT on urine proteinuria/albuminuria in the randomized control trials (n = 3) was 0.02 (95% CI, -0.29 to 0.33) and -0.13 (95% CI, -0.31 to 0.05) in the observational studies (n = 9). There was significantly less albuminuria among HT users (SMD -0.15, 95% CI, -0.27 to -0.04) in the 9 studies that only reported albuminuria as an outcome and in the 10 studies with a comparator arm (SMD -0.15, 95% CI, -0.26 to -0.04).

CONCLUSIONS

HT is associated with decreased odds of albuminuria, but some of the observed benefits may be related to reported outcomes, the presence of a comparator arm, and the type of study design.

Cardiorenal disease connection during post-menopause: The protective role of estrogen in uremic toxins induced microvascular dysfunction

Female gender, post-menopause, chronic kidney disease (CKD) and (CKD linked) microvascular disease are important risk factors for developing heart failure with preserved ejection fraction (HFpEF). Enhancing our understanding of the interrelation between these risk factors could greatly benefit the identification of new drug targets for future therapy. This review discusses the evidence for the protective role of estradiol (E₂) in CKD-associated microvascular disease and related HFpEF. Elevated circulating levels of uremic toxins (UTs) during CKD may act in synergy with hormonal changes during post-menopause and could lead to coronary microvascular endothelial dysfunction in HFpEF. To elucidate the molecular mechanism involved, published transcriptome datasets of indoxyl sulfate (IS), high inorganic phosphate (HP) or E₂ treated human derived endothelial cells from the NCBI Gene Expression Omnibus database were analyzed. In total, 36 genes overlapped in both IS- and HP-activated gene sets, 188 genes were increased by UTs (HP and/or IS) and decreased by E₂, and 572 genes were decreased by UTs and increased by E₂. Based on a comprehensive in silico analysis and literature studies of collected gene sets, we conclude that CKD-accumulated UTs could negatively impact renal and cardiac endothelial homeostasis by triggering extensive inflammatory responses and initiating dysregulation of angiogenesis. E₂ may protect (myo)endothelium by inhibiting UTs-induced inflammation and ameliorating UTs-related uremic bleeding and thrombotic diathesis via restored coagulation capacity and hemostasis in injured vessels.