Thirst Perception Research Articles

Training With Fluid Restriction Thrice A Week For Four Consecutive Weeks: Impact On Thirst Perception

Training With Fluid Restriction Thrice A Week For Four Consecutive Weeks: Impact On Thirst Perception

Thirst and the influence of ionic concentration; an investigation into the effect on salivary lubrication and the role of MUC5B

Saliva plays a crucial role in lubricating the oral cavity and maintaining a normal hydrated mouthfeel, with the main macromolecule in saliva, MUC5B, playing a significant role in its lubricating properties. Mucins form a hydrated biogel that covers the oral epithelium and forms part of the mucosal pellicle, maintaining proper hydration. This study investigates the relationship between ionic concentration, saliva lubrication, and the perception of oral dryness. At baseline, sodium was found to be ten times more concentrated in the mucosal pellicle compared to bulk saliva, in contrast to potassium which was only 1.5 times more concentrated in the pellicle. Increasing concentrations of mouthwashes containing sodium or potassium indicated a preferential sequestering of sodium in the mucosal pellicle with sodium chloride rinses being associated with an increased thirst perception. We therefore propose that sodium binds to MUC5B, reducing the electrostatic repulsions between its negatively charged moieties. This interaction subsequently leads to a compaction of the mucin structure, which decreases the hydration of MUC5B and reduces its lubricating properties. We determined that increased sodium concentrations compact the mucin structure as indicated by transmission electron microscopy. However, we found that increased sodium concentrations were associated with improved the lubrication of salivary and MUC5B films in an oral tribology mimic, decreasing the coefficient of friction from 0.044 to 0.018, and 0.416 to 0.100 with the addition of 200 mM sodium chloride for saliva and MUC5B, respectively. MUC5B was also demonstrated to become more hydrated with increasing ionic concentrations, as indicated by Quartz Crystal Microbalance with Dissipation. We therefore propose that increased hydration shells surrounding the sodium counterions are responsible for this improved lubrication via the hydration lubrication mechanism. Lastly, it was observed that the spinnbarkeit of saliva decreased with increasing ionic concentrations, indicating a reduced stretchiness in its rheological properties. However, the concentration of MUC5B alone did not appear to affect spinnbarkeit, highlighting that many factors influence the biophysical properties of saliva.

Utility of Body Weight, Urine Color, and Thirst Perception (WUT) in Determining Hydration in Young Adults.

The primary aim of this study was to assess the efficacy of the weight, urine, thirst (WUT) framework in predicting dehydration after a body water manipulation protocol, while concurrently determining the individual and interactive contributions of the model components. The total study sample was 93 participants (female, n = 47), recruited from two institutions. Phase 1 involved collecting daily hydration measures from free-living participants (Study 1, 58 participants for 3 days; Study 2, 35 participants for 7 days). Phase 2 entailed a two-hour passive heating protocol, where participants from Study 2 were randomly assigned to one of three groups that manipulated total body water over 24-hours using passive heating and fluid restriction. During each Phase, participants provided urine samples, underwent body mass measurements, and completed questionnaires pertaining to thirst perception. Morning and 24-hour urine samples were assessed for color, osmolality, and specific gravity. Differences between intervention groups, based on the probability of hydration status, were examined (ANOVA) and ridge regression analysis assessed the relative importance of variables within the WUT model. The study revealed significant differences among the intervention groups for predicted probability of dehydration, as determined by changes in body mass (p = 0.001), urine color (p = 0.044), and thirst perception (p < 0.001). Binomial ridge regression indicated that change in body mass (58%) and thirst perception (26%) were the most influential predictors of dehydration. These data support use of an enhanced version of the WUT model, underscoring the significance of changes in body mass and thirst perception in the assessment of hydration status.

Nurses’ perception of thirst in patients within palliative home care: a qualitative study

BackgroundThirst is the body’s natural urge to replenish fluids in response to a deficiency in hydration. Patients at the end of life gradually lose their independence and reach a point where they become unable to express their needs and can no longer drink on their own. In palliative care, the main advice is to provide regular oral care to relieve symptoms such as dry mouth and thirst. However, according to previous studies the prevalence of thirst and dry mouth remains.AimThe aim of this study was to describe palliative care, nurses’ views and experiences of thirst in end-of-life care in specialist palliative care units.MethodsA qualitative interview study with an inductive approach was conducted. Eighteen nurses working in six different specialist palliative care units in different hospitals in Sweden were interviewed. The interviews were transcribed and analysed with a content analysis approach according to Graneheim and Lundman.ResultsWhen nurses discuss thirst, they perceive thirst as a problem for the patient. This is attributable to various factors, including the patient breathing with an open mouth, a reduced level of awareness, and negligence on the part of the nursing staff. Signs of thirst are dry mouth, and frequently and intense sucking on the oral care stick during oral care. It also emerged that not all nurses perceived that dying patients experienced thirst. They believe that thirst is something that is reduced in the dying patient in the same way as hunger. The most important thing to them is to relieve the dry mouth by providing good oral care. Several issues, such as a lack of guidelines paired with the patient’s reduced consciousness and hence his/her lack of communication, make assessing thirst problematic.ConclusionNurses have different thoughts and experiences about thirst, where some perceive patients as thirsty while others perceive them as having a dry mouth. Nurses expressed that both evidence and guidelines are lacking.

Effect of Implementing Nursing Measures on Thirst Perception among Patients in Chest Intensive Care Unit

Effect of Implementing Nursing Measures on Thirst Perception among Patients in Chest Intensive Care Unit

Personalized Hydration Strategy to Improve Fluid Balance and Intermittent Exercise Performance in the Heat.

Sweat rate and electrolyte losses have a large inter-individual variability. A personalized approach to hydration can overcome this issue to meet an individual's needs. This study aimed to investigate the effects of a personalized hydration strategy (PHS) on fluid balance and intermittent exercise performance. Twelve participants conducted 11 laboratory visits including a VO2max test and two 5-day trial arms under normothermic (NOR) or hyperthermic (HYP) environmental conditions. Each arm began with three days of familiarization exercise followed by two random exercise trials with either a PHS or a control (CON). Then, participants crossed over to the second arm for: NOR+PHS, NOR+CON, HYP+PHS, or HYP+CON. The PHS was prescribed according to the participants' fluid and sweat sodium losses. CON drank ad libitum of commercially-available electrolyte solution. Exercise trials consisted of two phases: (1) 45 min constant workload; (2) high-intensity intermittent exercise (HIIT) until exhaustion. Fluids were only provided in phase 1. PHS had a significantly greater fluid intake (HYP+PHS: 831.7 ± 166.4 g; NOR+PHS: 734.2 ± 144.9 g) compared to CON (HYP+CON: 369.8 ± 221.7 g; NOR+CON: 272.3 ± 143.0 g), regardless of environmental conditions (p < 0.001). HYP+CON produced the lowest sweat sodium concentration (56.2 ± 9.0 mmol/L) compared to other trials (p < 0.001). HYP+PHS had a slower elevated thirst perception and a longer HIIT (765 ± 452 s) compared to HYP+CON (548 ± 283 s, p = 0.04). Thus, PHS reinforces fluid intake and successfully optimizes hydration status, regardless of environmental conditions. PHS may be or is an important factor in preventing negative physiological consequences during high-intensity exercise in the heat.

Perceived dehydration impairs endurance cycling performance in the heat in active males

Dehydration of >3 % body mass impairs endurance performance irrespective of the individual's knowledge of their hydration status, but whether knowledge of hydration status influences performance at lower levels of dehydration is unknown. This study examined whether perception of hydration status influenced endurance performance. After familiarisation, nine active males (age 25 ± 2 y, V̇O2peak 52.5 ± 9.1 mL kg min−1) completed two randomised trials at 34 °C. Trials involved an intermittent exercise preload (8 × 10 min cycling/5 min rest), followed by a 15 min all-out cycling performance test. During the preload in both trials, water was ingested orally every 10 min (0.3 mL kg body mass−1), with additional water infused into the stomach via gastric feeding tube to produce dehydration of ∼1.5 % body mass pre-performance test. Participants were told intra-gastric infusion was manipulated to produce euhydration (0 % dehydration; Perceived-EUH) or dehydration (2 % dehydration; Perceived-DEH) pre-performance test, which was told to them pre-preload and confirmed after body mass measurement pre-performance test. Body mass loss during the preload (Perceived-EUH 1.6 ± 0.2 %, Perceived-DEH 1.7 ± 0.2 %; P = 0.459), heart rate, gastrointestinal temperature and RPE (P ≥ 0.110) were not different between trials. Thirst was greater at the end of the preload and performance test in Perceived-DEH (P ≤ 0.040). Work completed during the performance test was 5.6 ± 6.1 % lower in Perceived-DEH (187.4 ± 37.0 kJ vs. 176.9 ± 36.0 kJ; P = 0.038). These results suggest that at lower levels of dehydration (<2 % body mass), an individual's perception of their hydration status could impair their performance, as well as their thirst perception.

TMEM63B channel is the osmosensor required for thirst drive of interoceptive neurons

Thirst plays a vital role in the regulation of body fluid homeostasis and if deregulated can be life-threatening. Interoceptive neurons in the subfornical organ (SFO) are intrinsically osmosensitive and their activation by hyperosmolarity is necessary and sufficient for generating thirst. However, the primary molecules sensing systemic osmolarity in these neurons remain elusive. Here we show that the mechanosensitive TMEM63B cation channel is the osmosensor required for the interoceptive neurons to drive thirst. TMEM63B channel is highly expressed in the excitatory SFO thirst neurons. TMEM63B deletion in these neurons impaired hyperosmolarity-induced drinking behavior, while re-expressing TMEM63B in SFO restored water appetite in TMEM63B-deficient mice. Remarkably, hyperosmolarity activates TMEM63B channels, leading to depolarization and increased firing rate of the interoceptive neurons, which drives drinking behavior. Furthermore, TMEM63B deletion did not affect sensitivities of the SFO neurons to angiotensin II or hypoosmolarity, suggesting that TMEM63B plays a specialized role in detecting hyperosmolarity in SFO neurons. Thus, our results reveal a critical osmosensor molecule for the generation of thirst perception.

Relieving Perception of Thirst and Xerostomia in Patients with Palliative and End-of-life Care Needs: A Rapid Review.

Thirst and dry mouth are interlinked symptoms that frequently cause significant distress for patients with life-limiting conditions. The objective of this rapid review was to identify and synthesize effective interventions that relieve perceptions of thirst and dry mouth of patients with palliative care and end-of-life care needs. Eligible studies were undertaken in clinical settings, with patients experiencing thirst-related distress and/or dry mouth. This review of peer-reviewed literature was conducted following aspects of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. The main outcomes of interest were: 1) efficacy of thirst and dry mouth interventions for patient, and 2) patient, caregiver, and staff acceptability and satisfaction of the interventions. Scientific journal articles were retrieved through searches in electronic databases of MEDLINE (Ovid), CINAHL (EBSCO), and AgeLine (EBSCO). Eleven studies were included for analysis and synthesis of the results. Most studies either focused on a dry mouth intervention or reported dry mouth outcomes within a broader thirst intervention (n=9/11 studies). Standard oral care was the common intervention type (n=5/11). All but one dry mouth intervention reported statistical improvement in outcomes of interest. All studies that reported on thirst were conducted in an Intensive Care Unit (ICU) setting (n=4/4). No studies specifically addressed thirst in patients in specialist palliative care settings. Evidence from this review suggests that thirst interventions established within the ICU setting may prove effective for treatment of terminally ill patients receiving specialist palliative care.

Disinhibition augments thirst perception from two dehydrating stimuli in men

Physiological systems controlling water and energy ingestion are coordinated. Whether maladaptive eating behavior and appetite for water are linked is unknown. Thus, we sought to investigate the association between maladaptive eating and both thirst and water drinking behavior with two dehydrating conditions. Twenty-two lean men and 20 men with obesity (mean age 32.3 ± 8.4 years and 30.0 ± 11.1 years, respectively) completed the Three-Factor Eating Questionnaire (TFEQ) and Gormally Binge Eating Scale. On separate days, volunteers were dehydrated by a 2-h hypertonic saline infusion and a 24-h water deprivation, and thirst was measured on a 100-mm visual analogue scale (VAS) during each procedure. After each dehydrating condition, ad libitum water intake was measured. In the saline infusion, higher Disinhibition on the TFEQ was associated with thirst in the lean group (β = 4.2 mm VAS, p = 0.03) but not in the group with obesity (p = 0.51). In the water-deprivation condition, higher Disinhibition was also associated with thirst in the lean group (β = 5.6 mm VAS, p = 0.01) with the strength of relationship being 3.5-fold stronger than that observed in the group with obesity (β = 1.6 mm VAS, p = 0.0003). Hunger, Restraint, and binge-eating scores were not associated with thirst in either dehydrating condition (all p > 0.05). Maladaptive eating behaviors were not associated with ad libitum water intake (all p > 0.05). Disinhibition is associated with higher thirst perception in healthy weight individuals and may be attenuated in obesity. The characteristics of disinhibition which typically includes a heightened readiness to eat, may reflect a more general phenotype that also reflects a readiness to drink.

Post-Exercise Voluntary Drinking Cessation Is Associated with the Normalization of Plasma Osmolality and Thirst Perception, but Not of Urine Indicators or Net Fluid Balance.

Post-exercise rehydration has been widely studied, with particular emphasis on retention of ingested fluid; comparatively little research has been conducted on why we drink more or less. To identify physiological values corresponding to voluntary drinking cessation (VDC), nine males exercised intermittently at 70–80% HRmax in the heat (WBGT = 28.1 ± 0.7 °C) to achieve a dehydration of approximately 4.0% body mass (BM). After exercise, participants were instructed to drink water as long and as much as they needed. Urine color (Ucolor), specific gravity (USG), osmolality (Uosm), plasma osmolality (Posm), fullness, BM, and thirst perception (TP) were measured pre- and post-exercise and at VDC. Each variable was compared for the three points in time with a one-way ANOVA. Participants reached dehydration of −3.6 ± 0.3% BM. Pre-exercise USG (1.022 ± 0.004) was lower than at VDC (1.029 ± 0.004, p = 0.022), Uosm did not change over time (p = 0.217), and Ucolor was lower pre-exercise (3.4 ± 0.7) vs. post-exercise (5.5 ± 1.23, p = 0.0008) and vs. VDC (6.3 ± 1.1, p < 0.0001). Posm showed a difference between pre-exercise (289.5 ± 2.3) and post-exercise (297.8 ± 3.9, p = 0.0006) and between post-exercise and VDC (287.3 ± 5.4, p < 0.0001). TP post-exercise (96.4 ± 4.34) was significantly higher than pre-exercise (36.2 ± 19.1) and VDC (25.0 ± 18.2, p < 0.0001). At VDC, participants had recovered 58.7 ± 12.1% of BM loss. At the point of voluntary drinking cessation, Posm and thirst perception had returned to their pre-exercise values, while rehydration relative to initial BM was still incomplete.

Factors influencing thirst perception during the consumption of oral nutritional supplements in older adults

Oral Nutritional Supplements (ONS) are often used as a strategy to aid nutrient adequacy in older adults. Research has highlighted that thirst increases with ONS consumption. This, combined with older adults’ tendency for diminished thirst, may contribute to reduced ONS adherence. This study investigated how alterations in viscosity, protein content, and sweetness of ONS impact thirst perception after ONS consumption.Seventy-two older adults (mean age 71 ± 4 years, 27 men, 45 women) evaluated four ONS of varying protein contents, four ONS of varying sweetness, and four ONS of varying viscosities over three days, one day per ONS set. Each ONS was consumed over three sips (10 mL each). After three sips the panellists recorded their thirst, mouth-dryness, ‘prospective water consumption’, appetite (Visual Analogue Scales), and liking (9-point hedonic scale). Salivary flow was recorded at the start of each visit. ONS osmolality was also measured.Most panellists had diminished thirst and low salivary flow. Each ONS was hypertonic and those highest in protein had significantly higher osmolality. Thirst, mouth-drying, and ‘prospective water consumption’ were not significantly different following consumption of different ONS. Significant differences between cohort subgroups were observed. Non-denture wearers had higher ratings for ‘prospective water consumption’ compared to denture wearers. Those who needed regular reminders to drink water were significantly thirstier and had higher ratings for mouth-drying and ‘prospective water consumption’ than those who do not. Female panellists had lower liking for ONS, than males.

The Influence Of Menstrual Cycle Phase On Fluid Intake And Urinary Hydration Markers

Variations in female sex hormones across the menstrual cycle (MC) influence the osmotic threshold for release of the hormone arginine vasopressin, which alters fluid retention and thirst perception. However, fluid intake behaviors across the MC have yet to be explored. PURPOSE: To determine differences in fluid intake behaviors and hydration status across the menstrual cycle in naturally cycling females. METHODS: Seventeen naturally cycling females (mean ± SD; age, 24 ± 5 y; height, 163 ± 7 cm; mass, 71.3 ± 24.4 kg; body fat, 22.7 ± 9.3%) provided 24 h urine samples over three consecutive days during three timepoints throughout their MC; early follicular (MCEF, days 3-5), late follicular (MCLF, days 11-13), and mid-luteal (MCML, days 18-20) phases, where day 0 was defined as the start of menstruation. Participants also completed daily fluid and dietary intake logs to assess fluid intake. Urinary hydration biomarkers assessed included urine volume (UVOL), urine osmolality (UOSM), urine specific gravity (USG), and urine color (UCOL). MC phase was used in separate linear mixed effects models as a fixed effect predictor of total fluid intake (TFI, all fluids from beverages and foods) and urinary hydration biomarkers, with a random effect of participant. RESULTS: There was no significant effect of MC phase on TFI (MCEF, 3472 ± 1505 mL; MCLF, 3416 ± 1410 mL; MCML, 3331 ± 1703 mL; β [95% CI], -171.59 [-348.7, 6.8], p = 0.172). UVOL was significantly greater during MCEF (2.36 ± 1.33 L) compared to MCLF (2.09 ± 1.41 L) and MCML (2.20 ± 1.40 L), β = -0.145 [-0.268, -0.022], p = 0.022. UOSM was significantly greater during MCML (465 ± 217 mOsm·kg-1) than MCEF (393 ± 193 mOsm·kg-1) or MCLF (426 ± 203 mOsm·kg-1), (β = 44.90 [19.0, 70.8], p = 0.001). However, there was no impact of MC phase on UCOL (β = 0.064 [-0.12, 024], p = 0.489) or USG (β = 0.0003 [-0.001, 0.002], p = 0.751). CONCLUSION: Our results indicate fluid intake behaviors do not change across the menstrual cycle in naturally cycling females despite differences in 24 h urine volume and osmolality. Since mean total fluid intake exceeded daily adequate intake recommendations and 24 h urinary hydration markers indicated euhydration, the clinical implications of menstrual cycle phase on hydration status may be minimal, but this remains to be fully elucidated in women not meeting fluid intake guidelines.

Voluntary drinking prevents dehydration when following occupational heat stress recommendations

INTRODUCTIONFederal and local entities issue guidance that aims to maintain core temperature (TC) below 38.0°C in unacclimated workers exposed to heat. These heat stress recommendations prescribe work‐rest ratios as a function of wet bulb globe temperature (WBGT) and metabolic heat production (Hprod). Hydration recommendations are less nuanced and suggest drinking 237 mL of a cool sport drink every 15‐20 min for work in the heat exceeding 2 h. This drinking regimen is based on the premise that ad libitum drinking during heat exposure results in dehydration [defined as &gt;2% body mass loss (BML)] due to inadequate drinking. To our knowledge, this hydration guidance has not been examined under heat stress recommendation compliant scenarios. Thus, it is unknown if ad libitumdrinking results in dehydration during recommendation compliant work in the heat.PURPOSETest the hypothesis that ad libitum drinking during heat stress recommendation compliant work in the heat will result in &gt;2% BML.METHODSSix, healthy, unacclimated, euhydrated subjects (2 women; 27±5 y) completed four trials consisting of 4 h (half a workday) of exposure to WBGTs of 23.9±0.2°C (A), 26.3±0.9°C (B), 28.4±0.1°C (C), 29.2±0.7°C (D). Subjects walked on a treadmill evoking a Hprod of 481±95 W, which is the average Hprod for outdoor workers in the U.S. NIOSH‐compliant work‐rest ratios were prescribed as a function of WBGT and Hprod [work:rest per hour (in min) ‐ A: 60:0, B: 45:15, C: 30:30, D: 15:45] and subjects were provided 237 mL of a cool (10±4°C) flavor preferred sport drink (Gatorade) every 15 min and drank ad libitum. BML was determined from changes in nude body mass and correction for fluid intake and urine loss provided an estimate of sweat rate. TC (telemetry pill) is reported as an average over the trial and as the percent of time TC exceeded 38.0°C (Time &gt;38). Thirst perception (1 = not thirsty, 9 = very, very thirsty) is reported as an average over the trial. Data are presented as mean±SD (parametric) or median (interquartile range) (nonparametric).RESULTSAverage TC was higher in Trial A (37.8±0.4°C; p=0.05) and Trial B (37.6±0.3°C; p=0.03) versus Trial D (37.3±0.4°C) but did not differ between the other trials (p≥0.20). Time &gt;38 did not differ between trials (A: 24 (5,43)%, B: 6 (0,5)%, C: 0 (0,5)%, D: 0 (0,0)%; p=0.17). Sweat rate was higher in Trial A (0.5±0.1 L/h) versus Trial D (0.4±0.1 L/h; p=0.05) but did not differ between any other trials (p≥0.12). Thirst perception (A: 2±1 a.u., B: 2±0 a.u, C: 2±1 a.u, D: 2±0 a.u; p=0.20) and fluid intake (A: 1.6±0.6 L, B: 1.5±0.5 L, C: 1.7±0.5 L, D: 1.6±0.7 L; p=0.88) did not differ between trials. BML did not differ between trials (A: ‐0.9±0.9%, B: ‐0.8±0.6%, C: ‐0.5±0.4%, D: ‐0.3±0.6%; p=0.24). One subject in one trial lost &gt;2% body mass (Trial A: ‐2.7%).CONCLUSIONAd libitumdrinking during recommendation compliant work in the heat rarely resulted in dehydration. Modification of work‐rest ratios across a range of WBGTs while working at a fixed Hprod mostly maintained TC &lt;38.0°C when ad libitumdrinking was permitted. Thus, absolute fluid prescription may not be necessary to prevent dehydration if adhering to occupational heat stress recommendations and cool fluids are readily available.

Prevalence of Dehydration and The Relationship with Fluid Intake and Self-Assessment of Hydration Status in Czech First League Soccer Players.

The objective of this cross-sectional study was to evaluate the hydration status of Czech First League soccer players, and to compare the reported fluid intake, perceived fluid intake and thirst sensation of euhydrated (EU) and dehydrated (DE) players. The study involved 124 Czech male professional soccer players (age 25.2±5.0 years) participating in annual winter, pre-season laboratory testing. Hydration status was assessed based on urine specific gravity (USG), euhydration was set at USG≤1.020. Fluid intake and thirst perception were evaluated by a questionnaire. The sample mean for USG was 1.021±0.008, 56% of players were dehydrated. Reported daily fluid intake was significantly (p<0.001, d=0.95, large effect) higher in EU compared to DE players. Daily fluid intake negatively correlated with USG (rS=-0.46, p<0.001, medium effect). The fluid intake perception score was significantly (p=0.005, d=0.54, medium effect) better in EU compared to DE players. Reported intake perception scores negatively correlated with USG (rS=-0.32, p<0.001, medium effect). However, there was no correlation (rS=-0.09, p=0.34, trivial effect) between thirst perception scores and USG. Thirst perception scores were not significantly different between EU and DE players (p=0.35, d=0.18, trivial effect). Our results indicated that self-assessment of both daily fluid intake and perceived fluid intake matched with objective hydration status, while self-assessment of thirst perception was not an appropriate indicator of hydration status in elite soccer players.

Cross-cultural variation in thirst perception in hot-humid and hot-arid environments: Evidence from two small-scale populations.

Thirst is an evolved central homeostatic feedback system that helps regulate body water for survival. Little research has examined how early development and exposure to extreme environments and water availability affect thirst perception, particularly outside Western settings. Therefore, we compared two indicators of perceived thirst (current thirst and pleasantness of drinking water) using visual scales among Tsimane' forager-horticulturalists in the hot-humid Bolivian Amazon and Daasanach agro-pastoralists in hot-arid Northern Kenya. We examined how these measures of perceived thirst were associated with hydration status (urine specific gravity), ambient temperatures, birth season, age, and population-specific characteristics for 607 adults (n=378 Tsimane', n=229 Daasanach) aged 18+ using multi-level mixed-effect regressions. Tsimane' had higher perceived thirst than Daasanach. Across populations, hydration status was unrelated to both measures of thirst. There was a significant interaction between birth season and temperature on pleasantness of drinking water, driven by Kenya data. Daasanach born in the wet season (in utero during less water availability) had blunted pleasantness of drinking water at higher temperatures compared to those born in the dry season (in utero during greater water availability). Our findings suggest hydration status is not a reliable predictor of thirst perceptions in extreme-hot environments with ad libitum drinking. Rather, our findings, which require additional confirmation, point to the importance of water availability during gestation in affecting thirst sensitivity to heat and water feedback mechanisms, particularly in arid environments. Thirst regulation will be increasingly important to understand given climate change driven exposures to extreme heat and water insecurity.

Comparing thirst and spot urine concentrations in humans of differing body sizes: An observational study

Elevated body mass index (BMI) has been associated with elevated urine osmolality (UOsm), despite having higher total water intake, but it is unclear if overweight/obese individuals have reduced thirst. In this observational study, we found that overweight/obese individuals had higher UOsm compared to normal-weight individuals (749 ± 37 vs. 624 ± 35 mmol•kg−1; P < 0.01) while possessing similar thirst ratings (56.4 ± 3 vs. 51.6 ± 3 mm; P = 0.3). In this observational study, overweight/obese individuals possessed more concentrated urine in the absence of higher thirst perception.

Awareness of Fluid Losses Does Not Impact Thirst during Exercise in the Heat: A Double-Blind, Cross-Over Study.

Background: Thirst has been used as an indicator of dehydration; however, as a perception, we hypothesized that it could be affected by received information related to fluid losses. The purpose of this study was to identify whether awareness of water loss can impact thirst perception during exercise in the heat. Methods: Eleven males participated in two sessions in random order, receiving true or false information about their fluid losses every 30 min. Thirst perception (TP), actual dehydration, stomach fullness, and heat perception were measured every 30 min during intermittent exercise until dehydrated by ~4% body mass (BM). Post exercise, they ingested water ad libitum for 30 min. Results: Pre-exercise BM, TP, and hydration status were not different between sessions (p > 0.05). As dehydration progressed during exercise, TP increased significantly (p = 0.001), but it was the same for both sessions (p = 0.447). Post-exercise water ingestion was almost identical (p = 0.949) in the two sessions. Conclusion: In this study, thirst was a good indicator of fluid needs during exercise in the heat when no fluid was ingested, regardless of receiving true or false water loss information.

Evidence that variations in pretraining hydration status are related to the frequency of endurance training in elite adolescent sprinters.

Although the effect of dehydration on performance is widely studied, limited data concerning the levels of risk training types pose to hydration status exists. This study sought to determine: 1) pretraining hydration status in adolescent sprinters relative to non-athletes; 2) changes in hydration markers across a season of adolescent sprinters relative to non-athletes; and 3) if frequency of training type explains unique variance in hydration. Hydration (via pretraining urine osmolality [UOsm] and thirst perception [TP]), daily water intake (TWI) (via 24-h food/fluid diaries) and frequencies of resistance, endurance and sprint training types (via training regime questionnaires) were assessed in 26 sprinters (age: 15.6±1.9 years) and 26 non-athletes (age: 16.0±1.6 years), during 4 mesocycles (general [T1] and specific [T2] preparation; precompetitive [T3] and peaking [T4] phases), over 26 weeks. Most athletes (62-81%) and non-athletes (73-92%) were underhydrated (UOsm>700 mOsmol/kg) pretraining across the season, despite a low TP. There were significant time (P=0.042) and group (P=0.006) effects, and a main group by time interaction for UOsm (P=0.006) but not TP across the season, after controlling for TWI. Greater UOsm (in mOsmol/kg) were observed during T1 (906.3±250.1) and T2 (934.5±257.0) compared to T3 (852.1±268.8) and T4 (854.2±218.8). There was no significant change across the season for non-athletes. Frequencies of endurance training were positively associated with UOsm and explained unique variances across the season (R2 range from 7%-16%). Underhydration is high in the adolescent population. Training type may be related to the variations in hydration throughout a season, which may help to inform hydration practices of sprint athletes.

A randomized controlled trial of the GLP-1 receptor agonist dulaglutide in primary polydipsia.

BackgroundPrimary polydipsia, characterized by excessive fluid intake, carries the risk of water intoxication and hyponatremia, but treatment options are scarce. Glucagon-like peptide 1 (GLP-1) reduces appetite and food intake. In experimental models, GLP-1 has also been shown to play a role in thirst and drinking behavior. The aim of this trial was to investigate whether GLP-1 receptor agonists reduce fluid intake in patients with primary polydipsia.MethodsIn this randomized, double-blind, placebo-controlled, 3-week crossover trial, 34 patients with primary polydipsia received weekly dulaglutide (1.5 mg, Trulicity) in one treatment segment and placebo (0.9% sodium chloride) in the other. During the last treatment week, patients attended an 8-hour evaluation visit with free access to water. The primary endpoint was total fluid intake during the evaluation visits. Treatment effects were estimated using linear mixed-effects models. In a subset of 15 patients and an additional 15 matched controls, thirst perception and neuronal activity in response to beverage pictures were assessed by functional MRI.RESULTsPatients on dulaglutide reduced their fluid intake by 490 mL (95% CI: -780, -199; P = 0.002), from 2950 mL (95% CI: 2435, 3465) on placebo to 2460 mL (95% CI: 1946, 2475) on dulaglutide (model estimates), corresponding to a relative reduction of 17%. Twenty-four-hour urinary output was reduced by -943 mL (95% CI: -1473, -413; P = 0.001). Thirst perception in response to beverage pictures was higher for patients with primary polydipsia than for controls, and lower for patients on dulaglutide versus placebo, but functional activity was similar among groups and treatments.CONCLUSIONSGLP-1 receptor agonists reduce fluid intake and thirst perception in patients with primary polydipsia and could therefore be a treatment option for these patients.Trial registrationClinicaltrials.gov NCT02770885.FundingSwiss National Science Foundation (grant 32473B_162608); University Hospital and University of Basel; Young Talents in Clinical Research grant from the Swiss Academy of Medical Sciences and the Gottfried & Julia Bangerter-Rhyner Foundation; Top-up Grant from the PhD Programme in Health Sciences, University of Basel.