Estrogen effects on osmotic regulation of AVP and fluid balance

Multidisciplinary care of peripartum heart failure: A scientific statement of the Heart Failure Association of the ESC

Heart failure is the most common cardiovascular complication during pregnancy and the postpartum period. It is associated with increased risk of maternal morbidity and mortality as well as potentially life-threatening foetal pathology. Management of heart failure in pregnancy requires expert knowledge of cardiovascular disease as well as obstetrics which underscores the importance of multidisciplinary cardio-obstetrics teams in order to optimize diagnosis, treatment and outcome. This includes counselling of women at risk before and during the course of pregnancy in order to strengthen the relationship between medical specialists and patients, as well as to allow patient-centred delivery of care and improve quality of life.

Guidelines on the use of sex and gender in cardiovascular research

In cardiovascular research, sex and gender have not typically been considered in research design and reporting until recently. This has resulted in clinical research findings from which not only all women, but also gender-diverse individuals have been excluded. The resulting dearth of data has led to a lack of sex- and gender-specific clinical guidelines and raises serious questions about evidence-based care. Basic research has also excluded considerations of sex. Including sex and/or gender as research variables not only has the potential to improve the health of society overall now, but it also provides a foundation of knowledge on which to build future advances. The goal of this guidelines article is to provide advice on best practices to include sex and gender considerations in study design, as well as data collection, analysis, and interpretation to optimally establish rigor and reproducibility needed to inform clinical decision-making and improve outcomes. In cardiovascular physiology, incorporating sex and gender is a necessary component when optimally designing and executing research plans. The guidelines serve as the first guidance on how to include sex and gender in cardiovascular research. We provide here a beginning path toward achieving this goal and improve the ability of the research community to interpret results through a sex and gender lens to enable comparison across studies and laboratories, resulting in better health for all.

Linking Cardiovascular Risk With Estradiol Level in Men

Aim      To study the relationship between the cardiovascular risk and the level of estradiol in men of young and middle age. The main group included 71 patients with newly diagnosed hyperestrogenia (HE) (serum estradiol >41.2 pg/ ml). Using pseudorandomization, 68 men with normal estradiol level and age- and body weight index (BWI)-matched with the main group were included into the control group. Anthropometric data, bioimpedance variables, blood pressure (BP), and concentrations of estradiol, testosterone, glucose, and total cholesterol were analyzed in both groups.Results Patients of the main and control groups did not differ in age, BWI, and smoking status. Testosterone concentration was 10.18 nmol/l in the HE group and 12.18 nmol /l in the control group (p=0.006). Systolic BP was 142.0 mm Hg in the HE group and 135.2 mm Hg in the control group (p=0.011); diastolic BP was 90.3 mm Hg in the HE group and 86.2 mm Hg in the control group (p=0.008). Total cholesterol was 5.87 mmol/l in the HE group and 5.33 mmol/l in the control group (p=0.023). Blood glucose did not differ between the groups. The presence of HE in men 2.11 times (р=0.038) increased the probability of arterial hypertension. The intergroup difference by the SCORE scale did not reach statistical significance (р=0.172). BWI, waist and hip circumferences, and bioimpedance body composition parameters did not differ between the groups.Conclusion      In the studied cohort of young and middle-aged men, HE was an independent predictor for the presence of arterial hypertension. There were no significant intergroup differences in the total risk of cardiovascular diseases calculated with the SCORE scale.

Fluid balance during physical work in the heat is not modified by the menstrual cycle when fluids are freely available

We tested the hypothesis that women may be more at risk of becoming dehydrated during physical work in the heat in the early follicular phase (EF), compared with the late follicular (LF) and mid-luteal (ML) phases of the menstrual cycle when allowed free access to drink. Twelve healthy, eumenorrheic, unacclimated women (26 ± 5 yr) completed three trials (EF, LF, and ML phases) involving 4 h of exposure to 33.8 ± 0.8 °C, 54 ± 1% relative humidity. Each hour, participants walked on a treadmill for 30 min at a rate of metabolic heat production of 338 ± 9 W. Participants drank a cool, flavor-preferred non-caloric sport drink ad libitum. Nude body weight was measured pre- and post-exposure, and percent changes in body weight loss were interpreted as an index of changes in total body water. Total fluid intake and urine output were measured and sweat rate was estimated from changes in body mass corrected for fluid intake and urine output. Fluid intake was not different between phases (EF: 1,609 ± 919 mL; LF: 1,902 ± 799 mL; ML: 1,913 ± 671; P = 0.202). Total urine output (P = 0.543) nor sweat rate (P = 0.907) differed between phases. Percent changes in body mass were not different between phases (EF: -0.5 ± 0.9%; LF: -0.3 ± 0.9%; ML: -0.3 ± 0.7%; P = 0.417). This study demonstrates that the normal hormonal fluctuations that occur throughout the menstrual cycle do not alter fluid balance during physical work in the heat.NEW & NOTEWORTHY The effect of the menstrual cycle on fluid balance during physical work in the heat when fluids are freely available is unknown. This study demonstrates that fluid balance is not modified in women across three distinct phases of the menstrual cycle during physical work in the heat These results indicate that when women have free access to cool fluid during physical work in the heat, they respond similarly across all three phases to maintain fluid homeostasis across the menstrual cycle.

Fluid Balance, Sodium Losses and Hydration Practices of Elite Squash Players during Training

Elite squash players are reported to train indoors at high volumes and intensities throughout a microcycle. This may increase hydration demands, with hypohydration potentially impairing many key performance indicators which characterise elite squash performance. Consequently, the main aim of this study was to quantify the sweat rates and sweat [Na+] of elite squash players throughout a training session, alongside their hydration practices. Fourteen (males = seven; females = seven) elite or world class squash player’s fluid balance, sweat [Na+] and hydration practices were calculated throughout a training session in moderate environmental conditions (20 ± 0.4 °C; 40.6 ± 1% RH). Rehydration practices were also quantified post-session until the players’ next training session, with some training the same day and some training the following day. Players had a mean fluid balance of −1.22 ± 1.22% throughout the session. Players had a mean sweat rate of 1.11 ± 0.56 L·h−1, with there being a significant difference between male and female players (p < 0.05), and a mean sweat (Na+) of 46 ± 12 mmol·L−1. Players training the following day were able to replace fluid and sodium losses, whereas players training again on the same day were not. These data suggest the variability in players hydration demands and highlight the need to individualise hydration strategies, as well as training prescription, to ensure players with high hydration demands have ample time to optimally rehydrate.

Sex-specific issues of central and peripheral arginine-vasopressin concentrations in neurocritical care patients

BACKGROUND

Arginine-Vasopressin (AVP) is a nonapeptide that exerts multiple functions within the central nervous system and in the blood circulation that might contribute to outcome in critically ill patients. Sex differences have been found for mental and physical effects of AVP. For example, stress response and response due to hemorrhage differ between males and females, at least in animal studies. Data on humans -especially on AVP within the central nervous system (CNS)-are scarce, as cerebrospinal fluid (CSF) which is said to represent central AVP activity, has to be collected by means of invasive procedures. Here we present data on 30 neurocritical care patients where we simultaneously collected blood, CSF and saliva to analyze concentrations in the central and peripheral compartments.

PATIENTS AND METHODS

30 neurocritical care patients were included (13 male, 13 postmenopausal female, 4 premenopausal female) with a median age of 60 years. CSF, plasma and saliva were obtained simultaneously once in each patient and analyzed for AVP concentrations. Correlations between the central compartment represented by CSF, and the peripheral compartment represented by plasma and saliva, were identified. Relations between AVP concentrations and serum sodium and hematocrit were also determined.

RESULTS

In the whole patient collective, only very weak to weak correlations could be detected between AVP plasma/CSF, plasma/saliva and CSF/saliva as well as between AVP concentrations in each of the compartments and serum sodium/hematocrit. Regarding the subgroup of postmenopausal females, a significant moderate correlation could be detected for AVP in plasma and CSF and AVP CSF and serum sodium.

CONCLUSION

Absolute concentrations of AVP in central and peripheral compartments did not show sex differences. However, correlations between AVP plasma and CSF and AVP CSF and serum sodium in postmenopausal females indicate differences in AVP secretion and AVP response to triggers that deserve further examination.

Gender differences in clinical characteristics of emergency department patients involving illicit drugs use with analytical confirmation

BACKGROUND

To compare gender differences in socio-demographics, clinical manifestations, and laboratory test results of individuals who visited emergency departments (EDs) involving drug use.

METHODS

We retrospectively collected the data from 10 hospitals in Taiwan on drug-related ED visits from May 2017 to December 2020. We then examined the gender differences in their socio-demographics, clinical manifestations, urine toxicological results, and other laboratory tests results using chi-square or multivariable logistic regression.

RESULTS

Among individuals with drug-related ED visits, there were 546 (73.7%) men and 195 (26.3%) women. The most commonly used drugs were meth/amphetamine, followed by synthetic cathinones, and ketamine and its analogs. Compared to men, women were younger (32.03 ± 10.86 vs. 36.51 ± 10.84 years, p < 0.001) and more likely to use new psychoactive substances (NPS) (p = 0.011). Men were more likely to have human immunodeficiency virus infection (p < 0.001), whereas women were more likely to report psychiatric comorbidities (p = 0.003). Women were less likely to have aggressive behaviors (odds ratio (OR): 0.59, 95% CI: 0.39-0.88). After adjusting for socio-demographics and drug types, women were still less likely to have aggressive behaviors than men (adjusted OR: 0.59, 95% CI: 0.38-0.93). The likelihood of rhabdomyolysis and intensive care unit admission was higher in men (p < 0.001).

CONCLUSION

We found considerable gender differences in clinical characteristics among ED-visiting drug users, which could offer valuable information for the future development of more tailored gender-specific drug prevention and treatment strategies.

Estradiol dominance induces hemodilution and mild hematological alterations in mifepristone-treated rats

We examined that an estradiol-dominant state against progesterone could affect hematological parameters through hemodilution because estradiol is known to increase plasma volume via oncotic pressure. We performed a 2- and 3-week repeated oral dose study with mifepristone, a progesterone receptor antagonist, in female rats and examined erythrocyte counts, hemoglobin, hematocrit, plasma volume, levels of estradiol and progesterone, water intake, and water loss. Mifepristone treatment decreased some hematological parameters mildly and increased plasma volume. There were no remarkable changes in the balance of water intake and water loss through urination. Both estradiol and progesterone levels and the ratio of estradiol to progesterone increased. Therefore, our findings indicate that repeated mifepristone treatment increases estradiol levels and plasma volume, resulting in lower erythrocyte counts, hemoglobin, and hematocrit. The present study proved the possible contribution of estradiol to understanding the toxicological significance of mifepristone-induced hemodilution.

Response to a Water Bolus in Long Term Oral Contraceptive Users

The purpose of our study was to determine the responses to an acute water bolus in long-term oral contraception (OCP) users. Seventeen female volunteers (27 ± 5 y, 64.1 ± 13.7 kg, 39.6 ± 5.9 kg/LBM) provided consent and enrolled in our study. All were long-term OCP users and participated in two trials, one during the active pill (High Hormone, HH) dose of their prescribed OCP and one during the sham pill (Low Hormone, LH) dose. Participants reported to the laboratory euhydrated, were fed breakfast, remained seated for 60 min and were provided a bolus of room temperature water in the amount of 12 mL/kg/LBM. Urine output over 180 min was measured. Nude body mass was measured pre- and post-trial. Urine specific gravity (USG) and urine osmolality were analyzed. Between trials, there were no differences in 3-h total urine volume (P = 0.296), 3-h USG (P = 0.225), 3-h urine osmolality (P = 0.088), or 3-h urine frequency (P = 0.367). Heart rate was not different between trials (P = 0.792) nor over time (P = 0.731). Mean arterial pressure was not different between trials (P = 0.099) nor over time (P = 0.262). Perceived thirst demonstrated a significant main effect for increasing over time regardless of trial (P &lt; 0.001) but there was no difference between trials (P = 0.731). The urgency to void was not different between trials (P = 0.149) nor over time (P = 0.615). Plasma volume change was not different between trials (P = 0.847) (HH: −3.4 ± 5.0, LH post: −3.8 ± 4.5%) and plasma osmolality did not differ between trials (P = 0.290) nor over time (P = 0.967) (HH pre: 290 ± 4, HH post: 289 ± 4, LH pre: 291 ± 4, LH post: 291 ± 4 mosm/L). Blood glucose significantly decreased over time (P &lt; 0.001) but there was no difference between trials (P = 0.780) (HH pre: 95.9 ± 113.9, HH post: 86.8 ± 6.5, LH pre: 95.9 ± 13.5, LH post: 84.6 ± 9.4 mmol/L). Copeptin concentration did not differ between phases of OCP use (P = 0.645) nor from pre- to post-trial (P = 0.787) Despite fluctuations in hormone concentrations, responses to a water bolus seem to be unaffected in OCP users in euhydrated, resting conditions.

Utility of an Isotonic Beverage on Hydration Status and Cardiovascular Alterations

This study determined the beverage hydration index (BHI) and postprandial cardiac autonomic activity after consuming an isotonic beverage (IB) compared to distilled water (DW). Twenty-two participants (50% female; mean ± SD; age, 27 ± 3 year; height, 169.1 ± 12.6 cm; weight, 73.3 ± 13.8 kg; BF%, 23 ± 10%) completed two experimental trials where they consumed 1 L DW or an IB; after which urine volume and cardiac autonomic activity was measured through 240 min. Cardiac autonomic activity was quantified using heart rate (HR), log transformed heart rate variability measures (root mean square of successive R–R intervals; RMSSD; low frequency, LF; and high frequency, HF) and systolic time intervals (pre-ejection period, PEP). BHI was significantly greater after IB consumption at min 0 (MD [95% CI]; 1.31 [0.35, 2.27]), 180 min (0.09 [0.022, 0.16]), and 240 min (0.1 [0.03, 0.17]) compared to DW (p = 0.031). Net fluid balance was significantly greater in IB than DW at 180 min (90 [−16.80, 196.81]) and 240 min (106 [−13.88, 225.88]) (p = 0.037). HR decreased over time in both beverage trials but was higher following IB ingestion at 0 min (3.9 [−2.42, 10.22]), 30 min (5.3 [−0.94, 11.54]), and 60 min (2.7 [−3.42, 8.82]) (p = 0.0002). lnHF was greater 30 min post DW ingestion compared to IB (0.45 [−0.23, 1.13]) (p = 0.039). IB promotes greater fluid retention capacity compared to DW within 4 hours of consumption. The variations in cardiac autonomic measures may warrant further investigation in clinical populations (i.e., patients with autonomic failure).

Acclimation to a High-Salt Diet Is Sex Dependent

Background Premenopausal women are less likely to develop hypertension and salt-related complications than are men, yet the impact of sex on mechanisms regulating Na+ homeostasis during dietary salt challenges is poorly defined. Here, we determined whether female rats have a more efficient capacity to acclimate to increased dietary salt intake challenge. Methods and Results Age-matched male and female Sprague Dawley rats maintained on a normal-salt (NS) diet (0.49% NaCl) were challenged with a 5-day high-salt diet (4.0% NaCl). We assessed serum, urinary, skin, and muscle electrolytes; total body water; and kidney Na+ transporters during the NS and high-salt diet phases. During the 5-day high-salt challenge, natriuresis increased more rapidly in females, whereas serum Na+ and body water concentration increased only in males. To determine if females are primed to handle changes in dietary salt, we asked the question whether the renal endothelin-1 natriuretic system is more active in female rats, compared with males. During the NS diet, female rats had a higher urinary endothelin-1 excretion rate than males. Moreover, Ingenuity Pathway Analysis of RNA sequencing data identified the enrichment of endothelin signaling pathway transcripts in the inner medulla of kidneys from NS-fed female rats compared with male counterparts. Notably, in human subjects who consumed an Na+-controlled diet (3314-3668 mg/day) for 3 days, women had a higher urinary endothelin-1 excretion rate than men, consistent with our findings in NS-fed rats. Conclusions These results suggest that female sex confers a greater ability to maintain Na+ homeostasis during acclimation to dietary Na+ challenges and indicate that the intrarenal endothelin-1 natriuretic pathway is enhanced in women.

Serum Sodium Concentration and Increased Risk for Primary Epiretinal Membrane

Aims: To examine the prevalence of primary epiretinal membranes (ERMs) and associated systemic factors.

Methods: The cross-sectional, community-based Tongren Health Care Study enrolled participants who received regular health examinations in the Beijing Tongren Hospital from 2017 to 2019. Using fundus photographs, retinal specialists assessed the presence of ERMs and their systemic associations.

Results: Primary ERMs were detected in 841/22820 individuals, with a prevalence of 3.7% [95% confidence intervals (CI): 3.4–3.9%] in the total study population (mean age: 44.5 ± 13.8 years) and 6.5% (95% CI: 6.1–7.0%) in individuals aged 40+ years. In multivariable analysis, a higher ERMs prevalence was associated with older age [odds ratio (OR): 1.10; P < 0.001], higher serum cholesterol concentration (OR: 1.14; P = 0.003) and higher serum sodium concentration (SSC) (OR: 1.12; P < 0.001). In women, a higher SSC, even within the normal range, was associated with an increased risk of ERMs (OR: 1.19; P < 0.001). Female participants with an SSC of 144–145mmol/L as compared with those with an SSC of 135–137 mmol/L had a 5-fold increased odds of having ERMs (All women: OR: 5.33; P < 0.001; Women aged 40+years: OR: 4.63; P < 0.001).

Conclusion: Besides older age and higher serum cholesterol concentration, a higher SSC, even if within the normal range, was independently associated with a higher ERM prevalence in women.

The Rise of the Female Warfighter: Physiology, Performance, and Future Directions

ABSTRACT

Since 1948, the United States military has been open to both men and women as permanent party service members. However, in the majority of the time since, there have been a subset of military occupational specialties (MOS), or job descriptions, open only to men. In particular, jobs requiring more intense physical and/or environmental strain were considered to be beyond the physiological capabilities of women. In the present analysis, we review the literature regarding neuromuscular, physical performance, and environmental physiology in women, to highlight that women have no inherent limitation in their capacity to participate in relevant roles and jobs within the military, within accepted guidelines to promote risk mitigation across sexes. First, we discuss performance and injury risk: both neuromuscular function and physical capabilities. Second, physiological responses to environmental stress. Third, we discuss risk as it relates to reproductive health and nutritional considerations. We conclude with a summary of current physiological, performance and injury risk data in men and women that support our overarching purpose, as well as suggestions for future directions.

Hypogonadism in Women with Prader-Willi Syndrome-Clinical Recommendations Based on a Dutch Cohort Study, Review of the Literature and an International Expert Panel Discussion

Prader-Willi syndrome (PWS) is a rare neuroendocrine genetic syndrome. Characteristics of PWS include hyperphagia, hypotonia, and intellectual disability. Pituitary hormone deficiencies, caused by hypothalamic dysfunction, are common and hypogonadism is the most prevalent. Untreated hypogonadism can cause osteoporosis, which is already an important issue in PWS. Therefore, timely detection and treatment of hypogonadism is crucial. To increase understanding and prevent undertreatment, we (1) performed a cohort study in the Dutch PWS population, (2) thoroughly reviewed the literature on female hypogonadism in PWS and (3) provide clinical recommendations on behalf of an international expert panel. For the cohort study, we retrospectively collected results of a systematic health screening in 64 female adults with PWS, which included a medical questionnaire, medical file search, medical interview, physical examination and biochemical measurements. Our data show that hypogonadism is frequent in females with PWS (94%), but is often undiagnosed and untreated. This could be related to unfamiliarity with the syndrome, fear of behavioral changes, hygienic concerns, or drug interactions. To prevent underdiagnosis and undertreatment, we provide practical recommendations for the screening and treatment of hypogonadism in females with PWS.

Differential influences of dietary sodium on blood pressure regulation based on race and sex

There are clear differences between men and women, and differences among races, in the incidence and prevalence of hypertension. Furthermore, there is extensive inter-individual variability among humans in the extent to which sodium ingestion alters blood pressure. Orthostatic intolerance and orthostatic hypotension are more common in women; these are often treated with a high salt diet, which has variable efficacy in increasing blood volume and blood pressure. Conversely, people with certain forms of hypertension are often counseled to decrease their sodium intake. Non-Hispanic Black men and women have higher rates of hypertension compared to non-Hispanic White men and women and other racial/ethnic groups. In aggregate, Black women appear to have better orthostatic tolerance than White women. In the present paper, we summarize and evaluate the current evidence for mechanisms of blood pressure regulation in men and women, as well as differences between Black and White groups, with a focus on cardiovascular responses to salt and differences among these groups. We also provide a brief review of factors that are not traditionally considered to be "biological" - such as socio-economic disparities resulting from historic and contemporary inequity across racial groups. These non-biological factors have direct and substantial influences on cardiovascular mechanisms, as well as implications for the influences of salt and sodium intake on blood pressure and cardiovascular health. We conclude that both biological and socio-economic factors provide critical modulating influences when considering the impacts of sodium on cardiovascular health as functions of race and sex.

Depression and obesity among females, are sex specificities considered?

This study aimed to systematically review the relationship of obesity-depression in the female sex. We carried out a systematic search (PubMed, MEDLINE, Embase) to quantify the articles (controlled trials and randomized controlled trials) regarding obesity and depression on a female population or a mixed sample. Successively, we established whether the sex specificities were studied by the authors and if they reported on collecting data regarding factors that may contribute to the evolution of obesity and depression and that could be responsible for the greater susceptibility of females to those conditions. After applying the inclusion and exclusion criteria, we found a total of 20 articles with a female sample and 54 articles with a mixed sample. More than half of all articles (51.35%, n = 38) evaluated the relationship between depression and obesity, but only 20 (27.03%) evaluated this relationship among females; still, 80% of those (n = 16) presented supporting results. However, few articles considered confounding factors related to female hormones (12.16%, n = 9) and none of the articles focused on factors responsible for the binomial obesity-depression in the female sex. The resulting articles also supported that depression (and related impairments) influencing obesity (and related impairments) is a two-way road. This systematic review supports the concurrency of obesity-depression in females but also shows how sex specificities are ultimately under-investigated. Female sex specificity is not being actively considered when studying the binomial obesity-depression, even within a female sample. Future studies should focus on trying to understand how the female sex and normal hormonal variations influence these conditions.

Estrogen to Progesterone Ratio and Fluid Regulatory Responses to Varying Degrees and Methods of Dehydration

The purpose of this study was to investigate the relationship between volume regulatory biomarkers and the estrogen to progesterone ratio (E:P) prior to and following varying methods and degrees of dehydration. Ten women (20 ± 1 year, 56.98 ± 7.25 kg, 164 ± 6 cm, 39.59 ± 2.96 mL•kg•min⁻¹) completed four intermittent exercise trials (1.5 h, 33.8 ± 1.3°C, 49.5 ± 4.3% relative humidity). Testing took place in two hydration conditions, dehydrated via 24-h fluid restriction (Dehy, USG > 1.020) and euhydrated (Euhy, USG ≤ 1.020), and in two phases of the menstrual cycle, the late follicular phase (days 10–13) and midluteal phase (days 18–22). Change in body mass (%BMΔ), serum copeptin concentration, and plasma osmolality (P_osm) were assessed before and after both dehydration stimuli (24-h fluid restriction and exercise heat stress). Serum estrogen and progesterone were analyzed pre-exercise only. Estrogen concentration did not differ between phases or hydration conditions. Progesterone was significantly elevated in luteal compared to follicular in both hydration conditions (Dehy—follicular: 1.156 ± 0.31, luteal: 5.190 ± 1.56 ng•mL⁻¹, P < 0.05; Euhy—follicular: 0.915 ± 0.18, luteal: 4.498 ± 1.38 ng·mL⁻¹, P < 0.05). As expected, E:P was significantly greater in the follicular phase compared to luteal in both hydration conditions (Dehy—F:138.94 ± 89.59, L: 64.22 ± 84.55, P < 0.01; Euhy—F:158.13 ± 70.15, L: 50.98 ± 39.69, P < 0.01, [all •10³]). Copeptin concentration was increased following 24-h fluid restriction and exercise heat stress (mean change: 18 ± 9.4, P < 0.01). We observed a possible relationship of lower E:P and higher copeptin concentration following 24-h fluid restriction (r = −0.35, P = 0.054). While these results did not reach the level of statistical significance, these data suggest that the differing E:P ratio may alter fluid volume regulation during low levels of dehydration but have no apparent impact after dehydrating exercise in the heat.

Relationships between reproductive hormones and maternal pregnancy physiology in women conceiving with or without in vitro fertilization

We evaluated maternal pregnancy adaptations and their relationships with circulating hormones in women who conceived with or without in vitro fertilization (IVF). Pregnancies were grouped by corpus luteum (CL) number: 1 CL with physiological plasma relaxin concentration (P_RLN; spontaneous pregnancies); 0 CL without circulating RLN (programmed cycles); >1 CL with elevated P_RLN (ovarian stimulation). Major findings were that declines in plasma osmolality (P_osm) and plasma sodium concentration ([Formula: see text]) were comparable in the 1 CL and 0 CL cohorts, correlated with plasma estradiol and progesterone concentrations but not P_RLN; gestational declines in plasma uric acid (UA) concentration (P_UA) were attenuated after IVF, especially programmed cycles, partly because of subdued increases of renal UA clearance; and P_RLN and cardiac output (CO) were inversely correlated when plasma estradiol concentration was below ∼2.5 ng/mL but positively correlated above ∼2.5 ng/mL. Unexpectedly, P_RLN and plasma sFLT1 (P_sFLT1) were directly correlated. Although P_sFLT1 and CO were not significantly associated, CO was positively correlated with plasma placental growth factor (PLGF) concentration after the first trimester, particularly in women who conceived with 0 CL. Major conclusions are that 1) circulating RLN was unnecessary for gestational falls in P_osm and [Formula: see text]; 2) P_RLN and CO were inversely correlated during early gestation, suggesting that P_RLN in the lower range may have contributed to systemic vasodilation, whereas at higher P_RLN RLN influence became self-limiting; 3) evidence for cooperativity between RLN and estradiol on gestational changes in CO was observed; and 4) after the first trimester in women who conceived without a CL, plasma PLGF concentration was associated with recovery of CO, which was impaired during the first trimester in this cohort.

Let's talk about sex: Differences in drug therapy in males and females

Professor Henry Higgins in My Fair Lady said, 'Why can't a woman be more like a man?' Perhaps unintended, such narration extends to the reality of current drug development. A clear sex-gap exists in pharmaceutical research spanning from preclinical studies, clinical trials to post-marketing surveillance with a bias towards males. Consequently, women experience adverse drug reactions from approved drug products more often than men. Distinct differences in pharmaceutical response across drug classes and the lack of understanding of disease pathophysiology also exists between the sexes, often leading to suboptimal drug therapy in women. This review explores the influence of sex as a biological variable in drug delivery, pharmacokinetic response and overall efficacy in the context of pharmaceutical research and practice in the clinic. Prospective recommendations are provided to guide researchers towards the consideration of sex differences in methodologies and analyses. The promotion of disaggregating data according to sex to strengthen scientific rigour, encouraging innovation through the personalisation of medicines and adopting machine learning algorithms is vital for optimised drug development in the sexes and population health equity.

Influence of Peak Menstrual Cycle Hormonal Changes on Restoration of Fluid Balance After Induced Dehydration

The present study examined the impact of hormonal differences between late follicular (LF) and midluteal (ML) phases on restoration of fluid balance following dehydration. Ten eumenorrheic female participants were dehydrated by 2% of their body mass through overnight fluid restriction followed by exercise-heat stress. Trials were undertaken during the LF (between Days 10 and 13 of the menstrual cycle) and ML phases (between Days 18 and 23 of the menstrual cycle) with one phase repeated to assess reliability of observations. Following dehydration, participants ingested a volume equivalent to 100% of mass loss of a commercially available sports drink in four equal volumes over 30 min. Mean serum values for steroid hormones during the ML (estradiol [E2]: 92 ± 11 pg/ml, progesterone: 19 ± 4 ng/ml) and LF (estradiol [E2]: 232 ± 64 pg/ml, progesterone: 3 ± 2 ng/ml) were significantly different between phases. Urine tests confirmed no luteinizing hormone surge evident during LF trials. There was no effect of menstrual cycle phase on cumulative urine volume during the 3-hr rehydration period (ML: 630 [197-935] ml, LF: 649 [180-845] ml) with percentage of fluid retained being 47% (33-85)% on ML and 46% (37-89)% on LF (p = .29). There was no association between the progesterone:estradiol ratio and fluid retained in either phase. Net fluid balance, urine osmolality, and thirst intensity were not different between phases. No differences in sodium (ML: -61 [-36 to -131] mmol, LF: -73 [-5 to -118] mmol; p = .45) or potassium (ML: -36 [-11 to -80] mmol, LF: -30 [-19 to -89] mmol; p = .96) balance were observed. Fluid replacement after dehydration does not appear to be affected by normal hormonal fluctuations during the menstrual cycle in eumenorrheic young women.

Sex differences in the physiological responses to exercise-induced dehydration: consequences and mechanisms

Physiological strain during exercise is increased by mild dehydration (∼1%-3% body mass loss). This response may be sex-dependent, but there are no direct comparative data in this regard. This review aimed to develop a framework for future research by exploring the potential impact of sex on thermoregulatory and cardiac strain associated with exercise-induced dehydration. Sex-based comparisons were achieved by comparing trends from studies that implemented similar experimental protocols but recruited males and females separately. This revealed a higher core temperature (T_c) in response to exercise-induced dehydration in both sexes; however, it seemingly occurred at a lower percent body mass loss in females. Although less clear, similar trends existed for cardiac strain. The average female may have a lower body water volume per body mass compared with males, and therefore the same percent body mass loss between the sexes may represent a larger portion of total body water in females potentially posing a greater physiological strain. In addition, the rate at which T_c increases at exercise onset might be faster in females and induce a greater thermoregulatory challenge earlier into exercise. The T_c response at exercise onset is associated with lower sweating rates in females, which is commonly attributed to sex differences in metabolic heat production. However, a reduced sweat gland sensitivity to stimuli, lower fluid output per sweat gland, and sex hormones promoting fluid retention in females may also contribute. In conclusion, the limited evidence suggests that sex-based differences exist in thermoregulatory and cardiac strain associated with exercise-induced dehydration, and this warrants future investigations.

Fluid and electrolyte balance considerations for female athletes

This review explores the effects of oestrogen and progesterone fluctuations across the menstrual cycle on fluid and electrolyte balance. The review aims to provide information on this topic for the exercising female but also for researchers working in this field. Beginning with a basic introduction to fluid and electrolyte balance, the review goes on to describe how oestrogen and progesterone have independent and integrated roles to play in the regulation of fluid and electrolyte balance. Despite evidence that oestrogen can influence the osmotic threshold for arginine vasopressin release, and that progesterone can influence aldosterone production, these actions do not appear to influence fluid retention, plasma volume changes at rest and during exercise, or electrolyte losses. However, the large inter-individual variations in hormonal fluctuations throughout the menstrual cycle may mean that specific individuals with high fluctuations could experience disturbances in their fluid and electrolyte balance. During phases of oestrogen dominance (e.g. late-follicular phase) heat dissipation is promoted, while progesterone dominance (e.g. mid-luteal phase) promotes heat conservation with overall higher basal body temperature. However, these responses do not consistently lead to any change in observed sweat rates, heat-stress, or dehydration during exercise. Finally, the literature does not support any difference in fluid retention during post-exercise rehydration periods conducted at different menstrual cycle phases. Although these mean responses largely reveal no effects on fluid and electrolyte balance, further research is required particularly in those individuals who experience high hormonal fluctuations, and greater exploration of oestrogen to progesterone interactions is warranted.

Association between oral contraceptive use and incident heart failure

Aims

Oral contraceptives (OCs) are widely used in women of reproductive age, but their influences on heart failure (HF) development have yet to be reported. This study was performed to assess HF risk associated with OC use.

Methods and results

We studied women participating in the Multi‐Ethnic Study of Atherosclerosis with available data on OC use. Inverse probability of treatment weighting analyses were used to reduce baseline imbalances. Cox proportional hazards models were applied to evaluate the associations of OC use and HF risk. The primary analysis comprised a total of 3594 participants [average age 62.10 (10.24) years]. During an average follow‐up of 12.45 (3.75) years, 138 incident HF occurred. In unadjusted Cox model, OC use was associated with a decreased risk of HF [hazard ratio (HR) = 0.45, 95% confidence interval (CI) 0.31–0.64, P < 0.001]. However, in multivariable‐adjusted and inverse probability of treatment weighting models, the results were attenuated and became non‐significant (HR = 0.96, 95% CI 0.63–1.48, P = 0.86 and HR = 0.79, 95% CI 0.45–1.40, P = 0.43, respectively). Duration of OC use was not related to increased risks of HF. When stratifying HF into subtypes, similar associations were observed. In multivariable–adjusted regression models, OC use was positively associated with left ventricular end‐diastolic mass [coefficient (β) = 3.04, P = 0.006] and stroke volume (β = 1.76, P = 0.01 for the left ventricle; β = 2.17, P = 0.005 for the right ventricle) but had no impact on left ventricular ejection fraction (β = 0.09, P = 0.75) and right ventricular ejection fraction (β = 0.33, P = 0.25).

Conclusions

Oral contraceptive use in women of reproductive age does not portend increased risk of HF. However, whether the formulations or dosages differently impact this association should be further investigated.

Body Composition Over the Menstrual and Oral Contraceptive Cycle in Trained Females

Purpose: The influence of female sex hormones on body fluid regulation and metabolism homeostasis has been widely studied. However, it remains unclear whether hormone fluctuations throughout the menstrual cycle (MC) and with oral contraceptive (OC) use affect body composition (BC). Thus, the aim of this study was to investigate BC over the MC and OC cycle in well-trained females. Methods: A total of 52 eumenorrheic and 33 monophasic OC-taking well-trained females participated in this study. Several BC variables were measured through bioelectrical impedance analysis 3 times in the eumenorrheic group (early follicular phase, late follicular phase, and midluteal phase) and on 2 occasions in the OC group (withdrawal phase and active pill phase). Results: Mixed linear model tests reported no significant differences in the BC variables (body weight, body mass index, basal metabolism, fat mass, fat-free mass, and total body water) between the MC phases or between the OC phases (P > .05 for all comparisons). Trivial and small effect sizes were found for all BC variables when comparing the MC phases in eumenorrheic females, as well as for the OC cycle phases. Conclusions: According to the results, sex hormone fluctuations throughout the menstrual and OC cycle do not influence BC variables measured by bioelectrical impedance in well-trained females. Therefore, it seems that bioimpedance analysis can be conducted at any moment of the cycle, both for eumenorrheic women and women using OC.

Pharmacologic management of nocturnal polyuria: a contemporary assessment of efficacy, safety, and progress toward individualized treatment

This narrative review synthesizes current evidence on the medical management of nocturnal polyuria, including antidiuretic replacement therapy as well as other emerging modalities, with particular emphasis on areas of active investigation and future research directions. Relative to earlier formulations, the pharmacological profiles of novel desmopressin acetate nasal spray and orally disintegrating tablet formulations appear favorable in optimizing the balance between efficacy and safety. Additionally, several highly selective small-molecule arginine vasopressin 2 receptor agonists are under active development, while appropriately timed short-acting diuretics, pharmacotherapy for hypertension, nonsteroidal anti-inflammatory drugs, and sex hormone replacement therapy are also a focal point of extensive ongoing nocturnal polyuria research. Emerging laboratory technologies now make feasible a sub-stratification of nocturnal polyuria patients into substrate-based phenotypes for individualized treatment. An increasingly refined understanding of the pathogenesis of nocturnal polyuria, and arginine vasopressin dysregulation in particular, has also introduced new opportunities for point-of-care testing in patients with nocturnal polyuria.

Sex Differences in Renal Outcomes After Medical Treatment for Bilateral Primary Aldosteronism

A higher incidence of bilateral primary aldosteronism in women is reported. Treatment of bilateral primary aldosteronism usually involves mineralocorticoid receptor antagonists. However, the impact of sex on renal outcomes is unknown. We compared renal outcomes between the sexes after mineralocorticoid receptor antagonist initiation by analyzing data obtained from 415 female and 313 male patients with bilateral primary aldosteronism who were treated with spironolactone or eplerenone in the JPAS (Japan Primary Aldosteronism Study). Over the course of 5 years, the temporal reduction in the estimated glomerular filtration rate was greater in women than in men (P<0.001). Systolic blood pressure levels were equal between the sexes, despite higher doses of antihypertensive drugs in men. The mean of the annual decline in estimated glomerular filtration rate during what we termed the late phase, or 6 to 60 months after mineralocorticoid receptor antagonist initiation, was larger in women than in men after adjusting for patient characteristics (-1.33 mL/min per 1.73 m² per year versus -1.04 mL/min per 1.73 m² per year, P<0.01). Female sex was a significant predictor of greater annual decline during the late phase in patients taking spironolactone but not in those taking eplerenone. Spironolactone use and diabetes were independent predictors of a greater annual decline in estimated glomerular filtration rate during the late phase in women. These findings suggest that female sex is associated with poorer renal outcomes in patients receiving mineralocorticoid receptor antagonist for bilateral primary aldosteronism.

Integrative cardiovascular control in women: Regulation of blood pressure, body temperature, and cerebrovascular responsiveness

Over the past several decades, it has become increasingly clear that women have distinct cardiovascular profiles compared to men. In this review, our goal is to provide an overview of the literature regarding the influences of female sex and reproductive hormones (primarily estradiol) on mechanisms of cardiovascular control relevant to regulation of blood pressure, body temperature, and cerebral blood flow. Young women tend to have lower resting blood pressure compared with men. This sex difference is reversed at menopause, when women develop higher sympathetic nerve activity and the risk of systemic hypertension increases sharply as postmenopausal women age. Vascular responses to thermal stress, including cutaneous vasodilation and vasoconstriction, are also affected by reproductive hormones in women, where estradiol appears to promote vasodilation and heat dissipation. The influence of reproductive hormones on cerebral blood flow and sex differences in the ability of the cerebral vasculature to increase its blood flow (cerebrovascular reactivity) are relatively new areas of investigation. Sex and hormonal influences on integrative blood flow regulation have further implications during challenges to physiological homeostasis, including exercise. We propose that increasing awareness of these sex-specific mechanisms is important for optimizing health care and promotion of wellness in women across the life span.

Pain Across the Menstrual Cycle: Considerations of Hydration

Chronic pain – pain that persists for more than 3 months – is a global health problem and is associated with tremendous social and economic cost. Yet, current pain treatments are often ineffective, as pain is complex and influenced by numerous factors. Hypohydration was recently shown to increase ratings of pain in men, but studies in this area are limited (n = 3). Moreover, whether hypohydration also affects pain in women has not been examined. In women, changes in the concentrations of reproductive hormones across menstrual phases may affect pain, as well as the regulation of body water. This indicates potential interactions between the menstrual phase and hypohydration on pain, but this hypothesis has yet to be tested. This review examined the literature concerning the effects of the menstrual phase and hypohydration on pain, to explore how these factors may interact to influence pain. Future research investigating the combined effects of hypohydration and menstrual phase on pain is warranted, as the findings could have important implications for the treatment of pain in women, interpretation of previous research and the design of future studies.

Effects of sex and menstrual cycle on volume-regulatory responses to 24-h fluid restriction

Reproductive hormones have significant nonreproductive physiological effects, including altering fluid regulation. Our purpose was to explore the impact of sex and menstrual cycle (MC) phase on volume-regulatory responses to 24-h fluid restriction (24-h FR). Participants (men: n = 12, 20 ± 2 yr; women: n = 10, 20 ± 1 yr) were assigned two randomized and counterbalanced fluid prescriptions [Euhy: euhydrated, urine specific gravity (USG) < 1.020; Dehy: 24-h FR, USG > 1.020]. Men completed both (MEuhy, MDehy), while women completed both in the late-follicular (days 10-13; FDehy, FEuhy) and midluteal (days 18-22; LDehy, LEuhy) phases. We measured body mass, plasma and urine osmolality (P_osm, U_osm), urine specific gravity (USG), urine color (U_col), and serum copeptin; 24-h FR yielded mild dehydration without influence of sex or MC (P > 0.05). Copeptin increased in men following Dehy (pre: 8.2 ± 5.2, post: 15.8 ± 12.6, P = 0.04) but not in women (FDehy pre: 4.3 ± 1.6, post: 10.5 ± 6.9, P = 0.06; LDehy pre: 5.6 ± 3.5, post: 10.4 ± 6.2, P = 0.16). In FDehy, P_osm increased following FR (pre: 288 ± 2, post: 292 ± 1, P = 0.03) but not in men (pre: 292 ± 3, post: 293 ± 2, P = 0.46). No MC differences were observed between body mass loss, P_osm, U_osm, USG, and copeptin (P > 0.05). These results suggest that volume-regulatory responses to 24-h FR were present in men but not in women, without apparent effects of the menstrual cycle.

Drinking to death: Hyponatraemia induced by synthetic phenethylamines

Synthetic phenethylamines are widely abused drugs, comprising new psychoactive substances such as synthetic cathinones, but also well-known amphetamines such as methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy). Cathinones and amphetamines share many toxicodynamic mechanisms. One of their potentially life-threatening consequences, particularly of MDMA, is serotonin-mediated hyponatraemia. Herein, we review the state of the art on phenethylamine-induced hyponatremia; discuss the mechanisms involved; and present the preventive and therapeutic measures. Hyponatraemia mediated by phenethylamines results from increased secretion of antidiuretic hormone (ADH) and consequent kidney water reabsorption, additionally involving diaphoresis and polydipsia. Data for MDMA suggest that acute hyponatraemia elicited by cathinones may also be a consequence of metabolic activation. The literature often reveals hyponatraemia-associated complications such as cerebral oedema, cerebellar tonsillar herniation and coma that may evolve to a fatal outcome, particularly in women. Ready availability of fluids and the recommendation to drink copiously at the rave scene to counteract hyperthermia, often precipitate water intoxication. Users should be advised about the importance of controlling fluid intake while using phenethylamines. At early signs of adverse effects, medical assistance should be promptly sought. Severe hyponatraemia (<130 mmol sodium/L plasma) may be corrected with hypertonic saline or suppression of fluid intake. Also, clinicians should be made aware of the hyponatraemic potential of these drugs and encouraged to report future cases of toxicity to increase knowledge on this potentially lethal outcome.

Osmotic stimulation of vasopressin acutely impairs glucose regulation: a counterbalanced, crossover trial

BACKGROUND

Epidemiological studies in humans show increased concentrations of copeptin, a surrogate marker of arginine vasopressin (AVP), to be associated with increased risk for type 2 diabetes.

OBJECTIVES

To examine the acute and independent effect of osmotically stimulated AVP, measured via the surrogate marker copeptin, on glucose regulation in healthy adults.

METHODS

Sixty subjects (30 females) participated in this crossover design study. On 2 trial days, separated by ≥7 d (males) or 1 menstrual cycle (females), subjects were infused for 120 min with either 0.9% NaCl [isotonic (ISO)] or 3.0% NaCl [hypertonic (HYPER)]. Postinfusion, a 240-min oral-glucose-tolerance test (OGTT; 75 g) was administered.

RESULTS

During HYPER, plasma osmolality and copeptin increased (P < 0.05) and remained elevated during the entire 6-h protocol, whereas renin-angiotensin-aldosterone system hormones were within the lower normal physiological range at the beginning of the protocol and declined following infusion. Fasting plasma glucose did not differ between trials (P > 0.05) at baseline and during the 120 min of infusion. During the OGTT the incremental AUC for glucose from postinfusion baseline (positive integer) was greater during HYPER (401.5 ± 190.5 mmol/L·min) compared with the ISO trial (354.0 ± 205.8 mmol/L·min; P < 0.05). The positive integer of the AUC for insulin during OGTT did not differ between trials (HYPER 55,850 ± 36,488 pmol/L·min compared with ISO 57,205 ± 31,119 pmol/L·min). Baseline values of serum glucagon were not different between the 2 trials; however, the AUC of glucagon during the OGTT was also significantly greater in HYPER (19,303 ± 3939 ng/L·min) compared with the ISO trial (18,600 ± 3755 ng/L·min; P < 0.05).

CONCLUSIONS

The present data indicate that acute osmotic stimulation of copeptin induced greater hyperglycemic responses during the oral glucose challenge, possibly due to greater glucagon concentrations.This study was registered at clinicaltrials.gov as NCT02761434.

Osmotic indices and kidney concentrating activity: population-based data on correlates and prognostic power

Background

Research data are limited on indices of osmotic equilibrium and of kidney concentrating activity (KCA). This study investigated correlates and prognostic power of these indices in a sample of the general population.

Methods

Urine osmolality (U-osm), plasma osmolality (P-osm), plasma creatinine and other variables were measured by the Gubbio Study for the 1988-92 exam (baseline). Plasma creatinine and other variables were re-measured in the 2001-07 exam (follow-up). KCA was assessed as the U-osm/P-osm ratio and kidney function as estimated glomerular filtration rate (eGFR).

Results

Baseline data were complete in 4220 adults, of whom 852 died before follow-up and 2795 participated in the follow-up. At baseline, the following independent cross-sectional associations were identified: female sex and higher urine flow with lower values of U-osm, P-osm and U-osm/P-osm ratio (P < 0.01); obesity with higher values of U-osm, P-osm and U-osm/P-osm ratio (P < 0.01); older age and lower eGFR with lower U-osm, lower U-osm/P-osm ratio and higher P-osm (P < 0.05); hypertension and smoking with lower U-osm and lower U-osm/P-osm ratio (P < 0.05) but not with P-osm. From baseline to follow-up, the annualized rate was 1.26% for mortality and -0.74 ± 0.76 mL/min × 1.73 m2 for eGFR change. Mortality was independently predicted by baseline U-osm and baseline U-osm/P-osm ratio (hazard ratio for one higher standard deviation was ≤0.91, 95% confidence interval was ≤0.97, P < 0.01), but not by baseline P-osm. The eGFR change was not independently predicted by baseline values of U-osm, P-osm and U-osm/P-osm ratio (P ≥ 0.4).

Conclusions

Sex, age, obesity, eGFR, urine flow, hypertension and smoking independently associated with U-osm and KCA. U-osm and KCA independently predicted mortality, but not kidney function change over time.

Effect of oestrogen-dependent vasopressin on HPA axis in the median eminence of female rats

The median eminence (ME) anatomically consists of external (eME) and internal (iME) layers. The hypothalamic neurosecretory cells terminate their axons in the eME and secrete their neurohormones regulating anterior pituitary hormone secretion involved in stress responses into the portal vein located in the eME. Magnocellular neurosecretory cells (MNCs) which produce arginine vasopressin (AVP) and oxytocin in the paraventricular (PVN) and supraoptic nuclei (SON) terminate their axons in the posterior pituitary gland (PP) through the iME. Here, we provide the first evidence that oestrogen modulates the dynamic changes in AVP levels in the eME axon terminals in female rats, using AVP-eGFP and AVP-DREADDs transgenic rats. Strong AVP-eGFP fluorescence in the eME was observed at all oestrus cycle stages in adult female rats but not in male transgenic rats. AVP-eGFP fluorescence in the eME was depleted after bilateral ovariectomy but re-appeared with high-dose 17β-oestradiol. AVP-eGFP fluorescence in the MNCs and PP did not change significantly in most treatments. Peripheral clozapine-N-oxide administration induced AVP-DREADDs neurone activation, causing a significant increase in plasma corticosterone levels in the transgenic rats. These results suggest that stress-induced activation of the hypothalamic-pituitary-adrenal axis may be caused by oestrogen-dependent upregulation of AVP in the eME of female rats.

Acute NaCl Loading Reveals a Higher Blood Pressure for a Given Serum Sodium Level in African American Compared to Caucasian Adults

Purpose: African American individuals are more prone to salt-sensitive hypertension than Caucasian individuals. Small changes in serum sodium (Na⁺) result in increased blood pressure (BP). However, it remains unclear if there are racial differences in BP responsiveness to increases in serum Na⁺. Therefore, the purpose of this investigation was to determine if African American adults have altered BP responsiveness to acute changes in serum Na⁺ compared to Caucasian adults.

Methods: We measured beat-by-beat BP, serum Na⁺, plasma renin activity (PRA), angiotensin II (Ang II), and aldosterone (Aldo) during a 60-min 3% NaCl infusion (hypertonic saline infusion, HSI) in 39 participants (19 African Americans, age: 23 ± 1, 20 Caucasians, age: 25 ± 1). Data reported as African American vs. Caucasian cohort, mean ± SEM.

Results: Baseline BP and serum Na⁺ were similar between groups and increased during HSI in both African American and Caucasian participants (p < 0.01). However, the peak change in serum Na⁺ was greater in African American participants (Δ5.8 ± 0.34 vs. Δ4.85 ± 0.38 mmol/L, p = 0.03). There was a significant group effect (p = 0.02) and an interaction between race and serum Na⁺ on systolic BP (p = 0.02). Larger categorical changes in serum Na⁺ corresponded to changes in systolic BP (p < 0.01) and African American participants demonstrated greater systolic BP responses for a given categorical serum Na⁺ increase (p < 0.01). Baseline Aldo was lower in African American adults (7.2 ± 0.6 vs. 12.0 ± 1.9 ng/dL, p = 0.03), there was a trend for lower baseline PRA (0.59 ± 0.9 vs. 1.28 ± 0.34 ng/mL/h, p = 0.07), and baseline Ang II was not different (14.2 ± 1.8 vs. 18.5 ± 1.4 pg/mL, p = 0.17). PRA and Aldo decreased during the HSI (p ≤ 0.01), with a greater decline in PRA (Δ–0.31 ± 0.07 vs. Δ–0.85 ± 0.25 ng/mL/h, p < 0.01) and Aldo (Δ–2.5 ± 0.5 vs. Δ–5.0 ± 1.1 ng/dL, p < 0.01) in Caucasian participants. However, the racial difference in PRA (p = 0.57) and Aldo (p = 0.59) reduction were no longer significant following baseline covariate analysis. Conclusion: African American individuals demonstrate augmented serum Na⁺ to an acute hypertonic saline load and greater systolic BP responsiveness to a given serum Na⁺. The altered BP response may be attributable to lower basal PRA and Aldo and a subsequently blunted RAAS response during the HSI.

Neither body mass nor sex influences beverage hydration index outcomes during randomized trial when comparing 3 commercial beverages

Background

The beverage hydration index (BHI) assesses the hydration potential of any consumable fluid relative to water. The BHI is a relatively new metric, and the impact of body mass, sex, and reproducibility has yet to be investigated.

Objectives

To assess the independent impact of body mass and sex on BHI using beverages not previously assessed, including an amino acid-based oral rehydration solution (AA-ORS), a glucose-containing ORS (G-ORS), and a sports drink (SpD), compared with water (control). The reproducibility of the results was examined using statistical modeling (bootstrap analysis).

Design

Using a repeated-measures design, 40 euhydrated and fasted subjects (17 male, 23 female; urine specific gravity <1.025) were studied on 4 separate occasions. During each trial, subjects ingested 1 L of each beverage, and urine output was measured immediately postingestion and at 1-h intervals for the next 4 h. The BHI was calculated as a ratio of each individual's cumulative urine output after drinking 1 L of water over their cumulative urine output after drinking each of the test beverages.

Results

The calculated mean ± SD BHIs of the beverages were as follows: water (1.0 ± 0.0), AA-ORS (1.15 ± 0.28), G-ORS (1.21 ± 0.28), and SpD (1.09 ± 0.26). The BHI for both AA-ORS and G-ORS was greater than that for water (P < 0.05). Despite overall differences in body mass, neither body mass nor sex independently affected BHI. Based upon statistical modeling, our results demonstrate excellent reproducibility of outcomes and external validity.

Conclusions

Our results suggest that the BHI may be used and interpreted with confidence independently of body mass or sex. Furthermore, a novel carbohydrate-free AA-ORS and a traditional commercially available G-ORS were superior to water in optimizing hydration, whereas SpD was not. This trial was registered at clinicaltrials.gov as NCT03262597.

The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review

BACKGROUND

Dehydration is highly prevalent and is associated with adverse cardiovascular and renal events. Clinical assessment of dehydration lacks sensitivity. Perhaps a patient's thirst can provide an accurate guide to fluid therapy. This systematic review examines the sensitivity of thirst in responding to changes in plasma osmolality in participants of any age with no condition directly effecting their sense of thirst.

METHODS

Medline and EMBASE were searched up to June 2017. Inclusion criteria were all studies reporting the plasma osmolality threshold for the sensation of thirst.

RESULTS

A total of 12 trials were included that assessed thirst intensity on a visual analogue scale, as a function of plasma osmolality (pOsm), and employed linear regression to define the thirst threshold. This included 167 participants, both healthy controls and those with a range of pathologies, with a mean age of 41 (20-78) years.The value ±95% CI for the pOsm threshold for thirst sensation was found to be 285.23 ± 1.29 mOsm/kg. Above this threshold, thirst intensity as a function of pOsm had a mean ± SEM slope of 0.54 ± 0.07 cm/mOsm/kg. The mean ± 95% CI vasopressin release threshold was very similar to that of thirst, being 284.3 ± 0.71 mOsm/kg.Heterogeneity across studies can be accounted for by subtle variation in experimental protocol and data handling.

CONCLUSION

The thresholds for thirst activation and vasopressin release lie in the middle of the normal range of plasma osmolality. Thirst increases linearly as pOsm rises. Thus, osmotically balanced fluid administered as per a patient's sensation of thirst should result in a plasma osmolality within the normal range. This work received no funding.

Oestradiol effects on neuroendocrine responses induced by water deprivation in rats

Water deprivation (WD) induces changes in plasma volume and osmolality, which in turn activate several responses, including thirst, the activation of the renin-angiotensin system (RAS) and vasopressin (AVP) and oxytocin (OT) secretion. These systems seem to be influenced by oestradiol, as evidenced by the expression of its receptor in brain areas that control fluid balance. Thus, we investigated the effects of oestradiol treatment on behavioural and neuroendocrine changes of ovariectomized rats in response to WD. We observed that in response to WD, oestradiol treatment attenuated water intake, plasma osmolality and haematocrit but did not change urinary volume or osmolality. Moreover, oestradiol potentiated WD-induced AVP secretion, but did not alter the plasma OT or angiotensin II (Ang II) concentrations. Immunohistochemical data showed that oestradiol potentiated vasopressinergic neuronal activation in the lateral magnocellular PVN (PaLM) and supraoptic (SON) nuclei but did not induce further changes in Fos expression in the median preoptic nucleus (MnPO) or subfornical organ (SFO) or in oxytocinergic neuronal activation in the SON and PVN of WD rats. Regarding mRNA expression, oestradiol increased OT mRNA expression in the SON and PVN under basal conditions and after WD, but did not induce additional changes in the mRNA expression for AVP in the SON or PVN. It also did not affect the mRNA expression of RAS components in the PVN. In conclusion, our results show that oestradiol acts mainly on the vasopressinergic system in response to WD, potentiating vasopressinergic neuronal activation and AVP secretion without altering AVP mRNA expression.

Sex Differences in the Hemorheological Effect of Antidiuretic Hormone

Experiments on rats showed that treatment with desmopressin in combination with water load contributes to the general nonspecific response of the blood. Increased blood viscosity, fibrinogen concentration, and erythrocyte aggregation were observed. Hemorheological changes in comparison with the control were less pronounced in females. Sex differences in erythrocyte aggregation were most significant.

Electrolyte Imbalance in Patients with Sheehan's Syndrome

BACKGROUND

We investigated the prevalence of electrolyte imbalance and the relationship between serum electrolyte and anterior pituitary hormone levels in patients with Sheehan's syndrome.

METHODS

In a retrospective study, we investigated 78 patients with Sheehan's syndrome. We also included 95 normal control subjects who underwent a combined anterior pituitary hormone stimulation test and showed normal hormonal responses.

RESULTS

In patients with Sheehan's syndrome, the serum levels of sodium, potassium, ionized calcium, magnesium, and inorganic phosphate were significantly lower than those in control subjects. The prevalence of hyponatremia, hypokalemia, hypocalcemia, hypomagnesemia, and hypophosphatemia in patients with Sheehan's syndrome was 59.0% (n=46), 26.9% (n=21), 35.9% (n=28), 47.4% (n=37), and 23.1% (n=18), respectively. Levels of sodium and ionized calcium in serum were positively correlated with levels of all anterior pituitary hormones (all P<0.05). Levels of potassium in serum were positively correlated with adrenocorticotrophic hormone (ACTH) and growth hormone (GH) levels (all P<0.05). Levels of inorganic phosphate in serum were positively correlated with levels of thyroid-stimulating hormone, prolactin, and GH (all P<0.05), and levels of magnesium in serum were positively correlated with delta ACTH (P<0.01).

CONCLUSION

Electrolyte imbalance was common in patients with Sheehan's syndrome. Furthermore, the degree of anterior pituitary hormone deficiency relates to the degree of electrolyte disturbance in patients with this disease.

Estradiol and osmolality: Behavioral responses and central pathways

Regulation of appropriate osmolality of body fluid is critical for survival, yet there are sex differences in compensatory responses to osmotic challenges. Few studies have focused on the role of sex hormones such as estradiol in behavioral responses to increases or decreases in systemic osmolality, and even fewer studies have investigated whether central actions of estrogens contribute to these responses. This overview integrates findings from a series of ongoing and completed experiments conducted in my laboratory to assess estradiol effects on water and NaCl intake in response to osmotic challenges, and on activity in central pathways that mediate such responses.

The risk of hyponatremia with desmopressin use for nocturnal polyuria

BACKGROUND

Desmopressin is used for treating nocturnal polyuria, but hyponatremia is an associated concern in the elderly due to impaired urinary dilution. This study was undertaken to characterize hyponatremia occurring in adults using desmopressin for nocturnal polyuria.

METHODS

Data from 172 patients who were prescribed desmopressin for nocturnal polyuria at a urology clinic from September 2010 through February 2013 were retrospectively analyzed. Demographic and laboratory parameters were investigated to examine the risk factors for desmopressin-associated hyponatremia.

RESULTS

The average follow-up serum sodium measured 21 ± 22 days after using desmopressin was 138 ± 5 mmol/l. Hyponatremia (<135 mmol/l) was found in 24 patients (14%), and it was severe in 7 (<126 mmol/l). In the hyponatremic patients, serum sodium decreased by 11 ± 6 mmol/l. Patients with hyponatremia were older than those with normonatremia (78 ± 7 vs. 68 ± 9 years, p < 0.0001). The presence of either hyponatremia-predisposing comorbidities or concurrent medications was associated with hyponatremia. Patients with hyponatremia had lower basal hemoglobin (11 ± 2 vs. 13 ± 2 g/dl, p < 0.001) and serum sodium (139 ± 2 vs. 140 ± 2 mmol/l, p < 0.05) than those with normonatremia. Multivariate logistic regression after adjustment for basal serum sodium showed that advanced age (OR 1.15; 95% CI 1.03-1.27) and lower hemoglobin level (OR 0.64; 95% CI 0.43-0.94) were independently associated with hyponatremia.

CONCLUSION

Hyponatremia is not infrequently associated with desmopressin use. Those with advanced age (≥65 years) and lower hemoglobin are at risk of desmopressin-associated hyponatremia and need to be carefully monitored.

Reproductive hormone influences on thermoregulation in women

The present discussion reviews current knowledge regarding influences of the primary reproductive hormones on mechanisms of thermoregulatory control in women. The human body is remarkably capable of maintaining body temperature within a few tenths of a degree of normal (37°C) over a wide range of activity and environmental exposures; this regulation is accomplished via integration of central and peripheral thermal information at the preoptic area of the anterior hypothalamus (PO/AH). We describe both central and peripheral mechanisms involved in controlling thermoregulation in humans, and how these mechanisms are affected by sex and hormone exposure. Estrogens generally promote vasodilation, heat dissipation, and lower body temperature and progesterone or progestins generally have the opposite effect. Estrogens and progesterone/progestins can also interact with androgens; this is an important point because androgens in the body can increase in both older and younger women. The study of reproductive hormone (estrogens, progesterone, luteinizing, and follicle stimulating hormones) effects on body systems is challenging because of the complex and multifaceted influences of these hormones, both individually and in combination. Thus, a number of methods to alter hormone exposure are explained in this article. We conclude that men and women do not exhibit major quantitative differences in physiological thermoregulatory responses to exercise and/or body heating when factors such as fitness and body size are taken into account. However, female and male reproductive hormones have important influences that can significantly alter individual thermoregulatory responses at various points throughout the lifespan.

Challenges and methodology for testing young healthy women in physiological studies

Physiological responses and control of body systems differ between women and men. Moreover, within women, female gonadal hormones have important influences on organs and systems outside of reproduction. Until the NIH Revitalization Act of 1993, laboratories focused physiological research primarily on men, and this focus placed limitations on women's health care. Thus, the NIH directive to include women required scientists and physicians studying humans to consider female reproductive physiology. Even though this directive was enacted over 20 years ago, there is still a great deal of misunderstanding as to the best methods to control hormones or account for changes in internal hormone exposure in women. This discussion describes common methods investigators use to include women in physiological studies and to examine the impact of female reproductive hormone exposure for research purposes. In some cases, the goal is to control for phase of the cycle, so women are studied when the endogenous hormones should be similar to each other. When the goal of the research is to examine the effects of hormones on a physiological response, it is important to use methods that will change hormone exposure in a controlled fashion. We recommend a method that employs gonadotropin-releasing hormone (GnRH) agonist or antagonist to suppress estrogens, gonadotropins, progesterone, and androgens followed by administration of these hormones. While this method is more invasive, it is safe and is the strongest research design to examine both hormone effects within women and between women and men.

Improvement in Sensorineural Hearing Loss During Pregnancy

Objective:

Hearing loss is known to occur in some pregnant women, but improvement in sensorineural thresholds has not been audiometrically characterized. Here, we describe a patient with a history of Ménière’s disease and vestibular migraine who experienced temporary recovery of her hearing during pregnancy.

Methods:

Audiograms were obtained from a 31-year-old female over the course of 2 successive pregnancies.

Results:

Audiograms revealed a substantial improvement in hearing by the third trimester during each pregnancy, with a rapid return to baseline thresholds after delivery.

Conclusion:

This case is unique in documenting improvements in hearing thresholds during pregnancy and substantiates the effects of hormonal changes on hearing thresholds in humans. It raises the intriguing possibility of hormonal therapy as a treatment for sensorineural hearing loss in specific clinical situations.