Comparison of IVC diameter ratio, BUN/creatinine ratio and BUN/albumin ratio for risk prediction in emergency department patients.

INTRODUCTION: Early prediction of patients' prognosis in the emergency department (ED) is important. Patients' conditions such as dehydration help predict prognosis. The ratio of serum blood urea nitrogen to creatinine (BUN/Cr ratio) and inferior vena cava (IVC) diameter is often used to determine dehydration. Also, serum albumin levels reflect nutritional conditions such as dehydration. In this study, we evaluated the performance of BUN/Cr ratio, IVC diameter ratio, and BUN/Albumin ratio as predictive markers for in-hospital mortality and ICU admission among various diseases in ED. MATERIAL AND METHODS: This retrospective cohort study utilized data from patients who had abdominal and pelvic computed tomography (APCT) performed at our institution from 2015 to 2018. The measurement of IVC diameter from computed tomography, the BUN/Cr ratio, and the BUN/Albumin ratio were calculated. Differences in the performance among the BUN/Cr ratio, the IVC diameter ratio, and the BUN/Albumin ratio for predicting outcomes were evaluated by the area under the receiver operating characteristic (AUROC) curve. RESULTS: A total of 914 patients were enrolled and 78 patients (8.5%) were admitted to the ICU, and 71 patients (7.8%) died during the clinical process. Multivariate logistic regression showed that only the BUN/Albumin ratio was a significant predictor of inhospital mortality and ICU admission. CONCLUSION: Among dehydration markers the BUN/Albumin ratio is a simple and useful tool for predicting the outcomes of patients visiting the ED.

Reference values for biochemical analytes in feral sheep from Socorro Island, Revillagigedo Archipelago, Mexico / [Valores de referência para analitos bioquímicos em carneiros selvagens na Ilha Socorro, Arquipélago de Revillagigedo, México]

To establish reference values for biochemical analytes related to freshwater shortage adaptation, a total of 376 blood samples were collected from feral sheep at Socorro Island, Revillagigedo Archipelago. Year-round variation was assessed by sampling at the beginning of each season defined by the March equinox, June solstice, September equinox, and December solstice. The resulting data set was analyzed using Gaussian distribution and descriptive statistics. Confidence intervals of 95% were established. Analysis of variance was used to compare the mean values of each season. Total cholesterol, triglycerides, urea, albumin, total protein, sodium ion, anion gap, creatine kinase, arginine vasopressin, and aldosterone showed concentrations above the reference range for domestic sheep. Triglycerides, urea, albumin, sodium ion, and aldosterone showed concentrations within the reference range for domestic goats. Most biochemical analytes showed differences (P<0.05) between seasons, with the highest values occurring during winter, and the lowest during spring. Results could help improve the accuracy of metabolic profiles used as a tool for evaluating dehydration indicators, and to describe the physiological mechanisms employed by feral sheep to cope with seasonal availability of freshwater.(AU)

Para estabelecer valores de referência para analitos bioquímicos relacionados à adaptação da escassez de água doce, um total de 376 amostras de sangue foram coletadas de carneiros selvagens na ilha de Socorro, no arquipélago de Revillagigedo. A variação durante todo o ano foi avaliada por amostragem no início de cada estação definida pelo equinócio de março, solstício de junho, equinócio de setembro e solstício de dezembro. O conjunto de dados resultante foi analisado usando distribuição Gaussiana e estatística descritiva. Intervalos de confiança de 95% foram estabelecidos. A análise de variância foi usada para comparar os valores médios de cada estação. O colesterol total, triglicerídeos, ureia, albumina, proteína total, íon sódio, hiato aniônico, creatina quinase, arginina vasopressina e aldosterona apresentaram concentrações acima do intervalo de referência para carneiros domésticos. Triglicerídeos, ureia, albumina, íon sódio e aldosterona apresentaram concentrações dentro da faixa de referência para cabras domésticas. A maioria dos analitos bioquímicos apresentou diferenças (P<0,05) entre as estações, com os maiores valores ocorrendo no inverno e os menores na primavera. Os resultados podem ajudar a melhorar a precisão dos perfis metabólicos usados como uma ferramenta para avaliar os indicadores de desidratação e descrever os mecanismos fisiológicos empregados pelas carneiros selvagens para lidar com a disponibilidade sazonal de água doce.(AU)

The effect of hydration status on plasma FGF21 concentrations in humans: A subanalysis of a randomised crossover trial.

AIM: Fibroblast growth factor 21 (FGF21) has recently been implicated in thirst in rodent models. The mechanisms for this are currently uncertain, and it is unclear whether hydration status can alter FGF21 concentrations, potentially providing an additional mechanism by which hypohydration induces thirst. The aim of this study is therefore to understand whether hydration status can alter circulating FGF21 in humans. METHODS: Using a heat tent and fluid restriction, we induced hypohydration (1.9% body mass loss) in 16 healthy participants (n = 8 men), and compared their glycaemic regulation to a rehydration protocol (heat tent and fluid replacement) in a randomised crossover design. RESULTS: After the hypohydration procedure, urine specific gravity, urine and serum osmolality, and plasma copeptin (as a marker for arginine vasopressin) increased as expected, with no change after the rehydration protocol. In the fasted state, the median paired difference in plasma FGF21 concentrations from the rehydrated to hypohydrated trial arm was -37 (interquartile range -125, 10) pg∙mL-1(P = 0.278), with average concentrations being 458 ± 462 pg∙mL-1 after hypohydration and 467 ± 438 pg∙mL-1 after rehydration; mean difference -9 ± 173 pg∙mL-1. CONCLUSION: To our knowledge, these are the first causal data in humans investigating hydration and FGF21, demonstrating that an acute bout of hypohydration does not impact fasted plasma FGF21 concentrations. These data may suggest that whilst previous research has found FGF21 administration can induce thirst and drinking behaviours, a physiological state implicated in increased thirst (hypohydration) does not appear to impact plasma FGF21 concentrations in humans.

The utility of ketones at triage: a prospective cohort study.

OBJECTIVE: To establish the relationship between serum point-of-care (POC) ketones at triage and moderate-to-severe dehydration based on the validated Gorelick Scales. DESIGN, SETTING AND PATIENTS: Prospective unblinded study from April 2016 to February 2017 in a paediatric emergency department. Patients aged 1 month to 5 years, with vomiting and/or diarrhoea and/or decreased intake with signs of moderate or severe dehydration or clinical concern for hypoglycaemia were eligible. MAIN OUTCOME MEASURES: The primary outcome was to describe the relationship between triage POC ketones to the two Gorelick Scales. Secondary outcomes were to examine the response of ketone levels to fluid/glucose administration and patient disposition. RESULTS: One-hundred and ninety-eight patients were included; median age 1.8 years. The median triage ketones were 4.6 (IQR 2.8-5.6) mmol/L. A weak correlation was identified between triage ketones and the 10-point Gorelick Scale (Spearman's ρ=0.217, p=0.002), however no correlation between triage ketones and the 4-point Gorelick Scale was identified. Those admitted had median triage ketones of 5.2 (IQR 4-6) mmol/L and repeat ketones of 4.6 (IQR 3.3-5.7) mmol/L compared with 4.2 (IQR 2.4-5.3) mmol/L and 2.9 (IQR 1.6-4.2) mmol/L in those discharged home. CONCLUSION: No correlation between triage POC ketones and the 4-point Gorelick Scale was established. POC ketones at triage have poor accuracy for predicting hospital admission. The elevated profile of POC ketones in non-diabetic children with acute illness suggests a potential target of tailored treatments for further research.

Determining the predictive capability of a Clinical Assessment Scoring Chart to differentiate severity of the clinical consequences of neonatal calf diarrhea relative to gold-standard blood gas analysis.

Neonatal calf diarrhea (NCD) is a major problem to calf health worldwide, in terms of both morbidity and mortality. A five-point ordinal scale clinical assessment scoring (CAS) chart was utilized to assess calves suffering from NCD-related clinical abnormalities (acidosis and dehydration) on commercial farms. The objective of this research was to determine the predictive capability of this CAS chart against gold standard blood gas parameters, designed to assist farmers in the accurate assessment of the clinical consequences of NCD. A total of 443 diarrheic and non-diarrheic calves were enrolled in the study. The CAS chart rated a calf's health from no clinical signs to varying degrees of clinical severity on a 0 (clinically normal) to 4 (grave) scale, based on clinical indicators including calf demeanour, ear position, mobility, suckle reflex, desire-to-feed, and enophthalmos. Blood gas analysis was conducted for individual calves, consisting of pH, base excess, Na+, K+, Ca2+, Cl-, glucose, total hemoglobin, bicarbonate, anion gap, and strong ion difference. Statistical evaluation was performed by comparison of the CAS score with blood gas profiles using ordinal logistic regression and a non-parametric estimation of the Receiver Operating Characteristics (ROC). The ROC analysis indicated that the CAS chart had acceptable specificity (>95%) with low sensitivity (<60%) in differentiating clinically normal from acidotic/dehydrated cases. Assessment of individual severity classes indicated that the chart can predict and differentiate both clinically normal and advanced cases from the other severity classes (peak estimations >80%) but had reduced accuracy in differentiating mild and moderate cases (peak estimations >50%). The chart, as presented, provides a simple tool to differentiate clinically normal from calves suffering the consequences of diarrhea, but fails to accurately differentiate severity for NCD related acidosis and dehydration. Further efforts are required to enhance the sensitivity and differential diagnostic value of this type of chart.

Association of Copeptin, a Surrogate Marker of Arginine Vasopressin, with Decreased Kidney Function in Sugarcane Workers in Guatemala.

BACKGROUND: Vasopressin is elevated in response to heat and dehydration and has been postulated to have a role in the chronic kidney disease of unknown origin being observed in Central America. The aims of this study were to examine whether the vasopressin pathway, as measured by copeptin, is associated with the presence of kidney dysfunction, and to examine whether higher fluid intake is associated with lower circulating copeptin and thereby preserves kidney health among sugarcane workers exposed to hot conditions. METHODS: Utilizing a longitudinal study of 105 workers in Guatemala, we examined relationships between hydration indices, plasma copeptin concentrations, and kidney function markers at 3 times during the 6-month harvest. We also examined whether baseline copeptin concentrations increased the odds of developing an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. RESULTS: Copeptin concentrations were positively associated with serum creatinine (ß 1.41, 95% CI 0.88-2.03) and negatively associated with eGFR (ß -1.07, 95% CI -1.43 to -0.70). In addition, as workers improved their hydration (measured by increases in fluid balance), copeptin concentrations were reduced, and this reduction was associated with an improvement in kidney function. CONCLUSIONS: Results suggest that copeptin should be studied as a potential prognostic biomarker.

Pre-exercise hypohydration prevalence in soccer players: A quantitative systematic review.

Pre-exercise hypohydration can impair soccer performance and has been extensively studied in different soccer populations. Therefore, the aim of this systematic review was to report hypohydration prevalence, measured by blood or urine samples, in different soccer populations based on sex (males and females), performance level (professional and recreational players) and context (training sessions and games). The Pubmed, Web of Science and SPORTDiscus databases were systematically searched until November 2018. Data were pooled to compare hypohydration prevalence between the different subgroups. Following the systematic search selection process, 24 studies were included. The results indicated that overall pre-exercise hypohydration prevalence was 63.3%, 37.4% and 58.8% for urine specific gravity (USG), urine osmolality (U Osm) and urine colour, respectively. Furthermore, no study implemented blood samples to examine hypohydration prevalence in soccer players. The subgroup analyses using USG data indicated that pre-exercise hypohydration prevalence was significantly higher amongst males (66.0%; p = 0.001), professional soccer players (66.2%; p = 0.020) and before a training session (79.6%; p < 0.001). Pre-exercise hypohydration prevalence was 46.8% among female soccer players, 55.6% in recreational soccer players and 41,3% before a game. The subgroup analyses using U Osm data indicated that hypohydration prevalence was significantly higher before a training session (52.6%; p = 0.023). Based on these results, it can be concluded that hypohydration prevalence in soccer players is of major concern. Future research should explore how pre-exercise hydration status can be improved in a sustainable way.

The presence of dehydration in paddy farmers in an area with chronic kidney disease of unknown aetiology.

AIM: Kidney disease of unknown aetiology (CKDu) has been a health problem in the rural farming community of the North Central province of Sri Lanka since the 1990s and various environmental factors have been postulated as contributing factors for this disease. The aim of our study was to find out whether farmers undergo dehydration which would lead to concentration of urine and the water soluble potentially toxic substance in the kidney, leading to damage of the renal tubules. Therefore, we studied a sample of healthy farmers who were CKDu-free to determine whether they were dehydrated. METHODS: Sample included healthy male paddy farmers of Padaviya in the Anuradhapura district. Plasma and urine osmolarity were recorded upon waking up in the morning and evening during the non-farming and farming seasons. Basic statistics and a 2 × 2 anova was done to test the interaction of time of day with farming activity. RESULTS: Farmers were dehydrated according to the plasma osmolarity especially in the mornings, irrespective of whether they were farming or not. Approximately 40% of the sample also demonstrated acute dehydration at the end of the day due to farming activity as indicated by both plasma and urine osmolarity and specific gravity. CONCLUSION: This study revealed that the farmers of the Padaviya area were either dehydrated or at the upper limit of euhydration sometime during the day irrespective of their activities during the day.

Reproductive state and water deprivation increase plasma corticosterone in a capital breeder.

Plasma corticosterone (CORT) concentrations fluctuate in response to homeostatic demands. CORT is widely recognized as an important hormone related to energy balance. However, far less attention has been given to the potential role of CORT in regulating salt and water balance or responding to osmotic imbalances. We examined the effects of reproductive and hydric states on CORT levels in breeding Children's pythons (Antaresia childreni), a species with substantial energetic and hydric costs associated with egg development. Using a 2 × 2 experimental design, we examined how reproduction and water deprivation, both separately and combined, impact CORT levels and how these changes correlate with hydration (plasma osmolality) and energy levels (blood glucose). We found that reproduction leads to increased CORT levels, as does dehydration induced by water deprivation. The combined impact of reproduction and water deprivation led to the largest increases in CORT levels. Additionally, we found significant positive relationships among CORT levels, plasma osmolality, and blood glucose. Our results provide evidence that both reproductive activity and increased plasma osmolality can lead to increased plasma CORT in an ectotherm, which could be explained by either CORT having a role as a mineralocorticoid or CORT being elevated as part of a stress response to resource imbalances.

Effect of Water Avoidance Stress on serum and urinary NGF levels in rats: diagnostic and therapeutic implications for BPS/IC patients.

Nerve growth factor (NGF) is thought to play a key role in chronic pain felt by bladder pain syndrome/interstitial cystitis (BPS/IC) patients by activating its high affinity receptor tropomyosin-related kinase subtype A (Trk A). Whether this pathway is also involved in the aggravation of pain sensation during stress events was here investigated. The levels of plasmatic NGF were increased in rats submitted to Water Avoidance Stress test (WAS), compared to controls. The administration of the alpha1A adrenoceptors blocker silodosin prevented the increase of plasmatic NGF. Urinary NGF levels were also moderately increased in animals submitted to WAS. WAS increased pain behaviour score, lowered abdominal mechanical pain threshold and increase voiding bladder reflex activity. These changes were prevented by the administration of TrkA antagonist GW441756. These findings prompt the use of plasmatic NGF as diagnosis tool for chronic visceral painful conditions and opens therapeutic opportunities for TrkA receptors antagonist/NGF sequestration.

Transient Ischemic Attack: Which Determines Diffusion-Weighted Image Positivity?

AIM OF THE STUDY: Diffusion-weighted image (DWI) of magnetic resonance imaging (MRI) can reveal high signal lesion in up to 50% of transient ischemic attack (TIA) patients. However, it is not well-known which factors determine developing DWI positivity. In order to answer this question, we analyzed factors relevant to DWI positivity in TIA patients. METHODS: We had 257 stroke patients at a university emergency/neurology wards. They were 140 men, 117 women, mean age 72 (45-88) years. Among them, 24 (9.3%) had TIA (14 men, 10 women, mean age 71 [58-82] years). All patients underwent a 1.5T MRI. In 24 TIA patients, we investigated the following parameters in relation with stroke maturation: ABCD2 score, smoking habits, blood profile, HbA1C, dyslipidemia, coagulation factors, carotid echography, electrocardiography, cardiac echography, chest X-ray, neurological symptom/signs, imaging, and recurrence of neurological symptom on follow-up. RESULTS: In 24 TIA patients, 13 (54%) were DWI positive and 11 (46%) were DWI negative. After an extensive analysis, all parameters were not relevant to DWI positivity except for plasma osmolarity, i.e., plasma osmolarity in DWI positive cases (305.3 mOsm/l) is significantly higher than that in DWI negative cases (301.3 mOsm/l) (P = .0064). As for recurrence, 4 of 24 TIA patients recurred. They were 1 (9.0%) of 11 DWI negative cases and 3 (23.1%) of 13 DWI positive cases. Therefore, DWI positive cases recurred more frequently than DWI negative cases did, although it did not reach statistical significance. CONCLUSIONS: TIA with DWI positivity in our institute was 54%, closely associated with initial dehydration and might predict stroke recurrence.

Dehydration of a diver during a hyperbaric chamber exposure with oxygen decompression.

Objective: An analysis of factors that may indicate both the type and degree of dehydration of a diver's body following a dry chamber hyperbaric exposure. Methods: The study was participated by 63 men - professional divers, with extensive diving experience, aged 24-51 years (average age 32.6). The subjects underwent two hyperbaric exposures, one to a pressure of 0.3 MPa and one to a pressure of 0.6 MPa, with oxygen decompression. The exposures were carried out in a hyperbaric chamber pursuant to the decompression tables of the Polish Navy, with the observance of a 24-hour interval between exposures. Blood samples were collected from the participants in order to perform a blood morphology test. Body weight was measured with the bioelectrical impedance method using the Maltron BioScan 920 device.The results were subjected to statistical analysis. The following blood morphology parameters were analyzed: hematocrit (Ht), erythrocyte size (MCV), color index (MCHC) and body weight composition: total water (TBW), extracellular water (ECW), intracellular water (ICW). Results: The studies have shown that during a hyperbaric exposure in the chamber the diver's body becomes dehydrated, with observable loss of both intracellular water as evidenced by the reduction of hematocrit content and erythrocyte size, as well as extracellular water, with the accompanying increase in the color index. Conclusions: Hyperbaric conditions are conducive to the dehydration of the diver's body, however to a degree which does not lead to an occurrence of health hazards. Good care for one's health through proper nutrition and hydration are sufficient preventive and protective measures.

Water deprivation does not augment sympathetic or pressor responses to sciatic afferent nerve stimulation in rats or to static exercise in humans.

Excess dietary salt intake excites central sympathetic networks, which may be related to plasma hypernatremia. Plasma hypernatremia also occurs following water deprivation (WD). The purpose of this study was to test the hypothesis that WD induces hypernatremia and consequently augments sympathetic and pressor responses to sympathoexcitatory stimuli in rats and humans. Sympathetic nerve activity (SNA) and arterial blood pressure (ABP) responses to sciatic afferent nerve stimulation (2-20 Hz) and chemical stimulation of the rostral ventrolateral medulla (RVLM) were assessed in rats after 48 h of WD and compared with normally hydrated control rats (CON). In a parallel randomized-crossover human experiment (n = 13 healthy young adults), sympathetic (microneurography) and pressor (photoplethysmography) responses to static exercise were compared between 16-h WD and CON conditions. In rats, plasma [Na+] was significantly higher in WD versus CON [136 ± 2 vs. 144 ± 2 (SD) mM, P < 0.01], but sciatic afferent nerve stimulation produced similar increases in renal SNA [5 Hz, 174 ± 34 vs. 169 ± 49% (SD), n = 6-8] and mean ABP [5 Hz, 21 ± 6 vs. 18 ± 7 (SD mmHg, n = 6-8]. RVLM injection of l-glutamate also produced similar increases in SNA and ABP in WD versus CON rats. In humans, WD increased serum [Na+] [140.6 ± 2.1 vs. 142.1 ± 1.9 mM (SD), P = 0.02] but did not augment sympathetic [muscle SNA: change from baseline (Δ) 6 ± 7 vs. 5 ± 7 (SD) bursts/min, P = 0.83] or mean ABP [Δ 12 ± 5 vs. 11 ± 8 (SD) mmHg, P = 0.73; WD vs. CON for all results] responses during the final minute of exercise. These findings suggest that despite eliciting relative hypernatremia, WD does not augment sympathetic or pressor responses to sciatic afferent stimulation in rats or to static exercise in humans. NEW & NOTEWORTHY Excess dietary salt intake excites central sympathetic networks, which may be related to plasma hypernatremia. Plasma hypernatremia also occurs following water deprivation (WD). We sought to determine whether plasma hypernatremia/hyperosmolality induced by WD augments sympathetic and pressor responses to sympathoexcitatory stimuli. Our findings suggest that WD does not augment sympathetic or pressor responses to sciatic afferent nerve stimulation in rats or to static exercise in humans.

Signs and Symptoms of Low-Intake Dehydration Do Not Work in Older Care Home Residents-DRIE Diagnostic Accuracy Study.

OBJECTIVES: To assess the diagnostic accuracy of commonly used signs and symptoms of low-intake dehydration in older care home residents. DESIGN: Prospective diagnostic accuracy study. SETTING: 56 care homes offering residential, nursing, and/or dementia care to older adults in Norfolk and Suffolk, United Kingdom. PARTICIPANTS: 188 consecutively recruited care home residents aged ≥65 years, without cardiac or renal failure and not receiving palliative care. Overall, 66% were female, the mean age was 85.7 years (standard deviation 7.8), and the median Mini-Mental State Examination MMSE score was 23 (interquartile range 18-26). INDEX TESTS: Over 2 hours, participants underwent double-blind assessment of 49 signs and symptoms of dehydration and measurement of serum osmolality from a venous blood sample. Signs and symptoms included skin turgor; mouth, skin, and axillary dryness; capillary refill; sunken eyes; blood pressure on resting and after standing; body temperature; pulse rate; and self-reported feelings of thirst and well-being. REFERENCE STANDARD: Serum osmolality, with current dehydration defined as >300 mOsm/kg, and impending dehydration ≥295 mOsm/kg. OUTCOME MEASURES: For dichotomous tests, we aimed for sensitivity and specificity >70%, and for continuous tests, an area under the curve in receiver operating characteristic plots of >0.7. RESULTS: Although 20% of residents had current low-intake dehydration and a further 28% impending dehydration, none of the commonly used clinical signs and symptoms usefully discriminated between participants with or without low-intake dehydration at either cut-off. CONCLUSIONS/IMPLICATIONS: This study consolidates evidence that commonly used signs and symptoms of dehydration lack even basic levels of diagnostic accuracy in older adults, implying that many who are dehydrated are not being identified, thus compromising their health and well-being. We suggest that these tests be withdrawn from practice and replaced with a 2-stage screening process that includes serum osmolarity, calculated from sodium, potassium, urea, and glucose levels (assessed routinely using the Khajuria and Krahn equation), followed by serum osmolality measurement for those identified as high risk (calculated serum osmolarity >295 mmol/L).

Assessing the impact of inadequate hydration on isotope-GFR measurement.

Guidelines state that patients undergoing isotope glomerular filtration rate (GFR) tests should maintain adequate hydration, but pragmatically these tests can coincide with procedures requiring the patient not to eat or drink ('nil-by-mouth') for up to 12 hours beforehand. This study investigated the impact of a 12-hour nil-by-mouth regime on GFR measurement. Twelve healthy volunteers were recruited from our institution. Exclusion criteria included diabetes mellitus, being under 18 years of age and pregnancy. Isotope GFR measurements were carried out on these volunteers twice. One of the tests adhered strictly to the British Nuclear Medicine Society (BNMS) guidelines for GFR measurement and the other test was carried out after the volunteers had refrained from eating or drinking anything for 12 hours. The order of these tests was randomly assigned. The results show that after a nil-by-mouth regime, participants' average absolute GFR fell from 108 ml/min to 97 ml/min (p < .01), while normalised GFR fell from 97 ml/min/1.73 m2 to 88 ml/min/1.73m2 (p < .01). Serum creatinine rose from 68 mmol/L to 73 mmol/L (p < .05). There were no changes in blood pressure, serum hydration markers or bio-impedance measured fluid status. Urine analysis showed statistically significant increases in urea, creatinine and osmolality levels after the nil-by-mouth regime. The results highlight the importance of following current guidelines recommending fluid intake during the procedure. Practitioners should consider what other outpatient appointments are being scheduled concurrently with a GFR test.

Effect of acute hypohydration on glycemic regulation in healthy adults: a randomized crossover trial.

The aim of this study was to investigate the acute effect of hydration status on glycemic regulation in healthy adults and explore underlying mechanisms. In this randomized crossover trial, 16 healthy adults (8 men, 8 women) underwent an oral glucose tolerance test (OGTT) when hypohydrated and rehydrated after 4 days of pretrial standardization. One day before OGTT, participants were dehydrated for 1 h in a heat tent with subsequent fluid restriction (HYPO) or replacement (RE). The following day, an OGTT was performed with metabolic rate measurements and pre- and post-OGTT muscle biopsies. Peripheral quantitative computer tomography thigh scans were taken before and after intervention to infer changes in cell volume. HYPO (but not RE) induced 1.9% (SD 1.2) body mass loss, 2.9% (SD 2.7) cell volume reduction, and increased urinary hydration markers, serum osmolality, and plasma copeptin concentration (all P ≤ 0.007). Fasted serum glucose [HYPO 5.10 mmol/l (SD 0.42), RE 5.02 mmol/l (SD 0.40); P = 0.327] and insulin [HYPO 27.1 pmol/l (SD 9.7), RE 27.6 pmol/l (SD 9.2); P = 0.809] concentrations were similar between HYPO and RE. Hydration status did not alter the serum glucose ( P = 0.627) or insulin ( P = 0.200) responses during the OGTT. Muscle water content was lower before OGTT after HYPO compared with RE [761 g/kg wet wt (SD 13) vs. 772 g/kg wet wt (SD 18) RE] but similar after OGTT [HYPO 779 g/kg wet wt (SD 15) vs. RE 780 g/kg wet wt (SD 20); time P = 0.011; trial × time P = 0.055]. Resting energy expenditure was similar between hydration states (stable between -1.21 and 5.94 kJ·kg-1·day-1; trial P = 0.904). Overall, despite acute mild hypohydration increasing plasma copeptin concentrations and decreasing fasted cell volume and muscle water, we found no effect on glycemic regulation. NEW & NOTEWORTHY We demonstrated for the first time that an acute bout of hypohydration does not impact blood sugar control in healthy adults. Physiological responses to mild hypohydration (<2% body mass loss) caused an elevation in copeptin concentrations similar to that seen in those with diabetes as well as reducing cell volume by ~3%; both of these changes had been hypothesized to cause a higher blood sugar response.

Dehydration Status Predicts Short-Term and Long-Term Outcomes in Patients with Cerebral Venous Thrombosis.

BACKGROUND: Dehydration is associated with a higher risk of poor outcome and venous thromboembolism in acute ischemic stroke patients. However, the relationship between dehydration and prognosis in patients with cerebral venous thrombosis (CVT) has not yet been investigated. METHODS: Consecutive CVT patients at the First Affiliated Hospital of Zhengzhou University were retrospectively identified from November 2011 through January 2017. Dehydration was evaluated by blood urea/creatinine (U/Cr) ratio > 80. Poor functional outcome was defined as modified Rankin Scale (mRS) of 3-6. Factors such as age, sex, coma, intracerebral hemorrhage, and straight sinus and/or deep CVT involved were adjusted to assess the relationship between dehydration, and prognosis at discharge and long-term follow-up in CVT patients. RESULTS: A total of 220 CVT patients were included, and 85 patients (38.64%) were dehydrated. Multivariate logistic regression analysis indicated that patients with dehydration had a higher risk of mRS of 3-6 at discharge (adjusted odds ratio [OR] 3.629, 95% confidence intervals [CI] 1.526-8.633, P = 0.004) and long-term outcome (adjusted OR 3.831, 95% CI 1.597-9.190, P = 0.003). Subgroup analysis stratified by potential factors that might be associated with dehydration, such as infection, vomiting, pregnancy, and/or postpartum, showed similar results. Multivariate Cox regression analysis further demonstrated that dehydration was associated with higher mortality (adjusted hazard ratio [HR] = 2.301, 95% CI 1.025-5.166, P = 0.043). CONCLUSIONS: The present findings indicate that dehydration is an independent predictor for short-term and long-term unfavorable functional outcome in patients with CVT.

Signs of Dehydration in Nursing Home Residents.

OBJECTIVES: Although dehydration can affect mental and physical health, there is no clear, consistent, and reproducible diagnostic tool for this condition in older people. We applied multiple methods to detect dehydration with the aim of assessing the value of using urine analysis for this purpose. DESIGN: Nonrandomized cohort study. SETTING AND PARTICIPANTS: Sixty nursing home residents, aged 64-103 (mean 84) years. METHODS: Sampling of morning urine, blood analyses, and clinical examination. A previously validated algorithm summarized the urine specific gravity, osmolality, creatinine, and color to a Fluid Retention Index (FRI). RESULTS: The cut-off for renal fluid conservation consistent with dehydration (FRI ≥ 4.0) was reached by 51% of the cohort. No statistically significant linear correlation was found between FRI and serum osmolality (mean 307.5 mOsmol/kg) or plasma sodium (mean 139 mmol/L), but the subjects reported less thirst with increasing FRI scores (linear correlation r = -0.35; P < .03). Clinical examinations of mucous membranes and tongue furrows did not correlate with other markers of dehydration. Subjects with sunken eyes had higher C-reactive protein (P < .02) and lower albumin (P < .002) concentrations in plasma than the others, while impaired skin turgor only correlated with age (P < .04). CONCLUSIONS/IMPLICATIONS: Renal fluid conservation consistent with dehydration was found in half of the nursing home residents, which could partially be accounted for by decreased thirst. Clinical examinations probably reflected the physical status and age more than dehydration. The lack of correlation between the serum osmolality and the FRI, both of which are purported to be gold standards for dehydration, raises questions about whether a gold standard exists.

Heat acclimatization blunts copeptin responses to hypertonicity from dehydrating exercise in humans.

Acclimatization favors greater extracellular tonicity from lower sweat sodium, yet hyperosmolality may impair thermoregulation during heat stress. Enhanced secretion or action of vasopressin could mitigate this through increased free water retention. Aims were to determine responses of the vasopressin surrogate copeptin to dehydrating exercise and investigate its relationships with tonicity during short and long-term acclimatization. Twenty-three participants completed a structured exercise programme following arrival from a temperate to a hot climate. A Heat Tolerance Test (HTT) was conducted on Day-2, 6, 9 and 23, consisting of 60-min block-stepping at 50% VO2 peak, with no fluid intake. Resting sweat [Na+ ] was measured by iontophoresis. Changes in body mass (sweat loss), core temperature, heart rate, osmolality (serum and urine) and copeptin and aldosterone (plasma) were measured with each Test. From Day 2 to Day 23, sweat [Na+ ] decreased significantly (adjusted P < 0.05) and core temperature and heart rate fell. Over the same interval, HTT-associated excursions were increased for serum osmolality (5 [-1, 9] vs. 9 [5, 12] mosm·kg-1 ), did not differ for copeptin (9.6 [6.0, 15.0] vs. 7.9 [4.3, 14.7] pmol·L-1 ) and were reduced for aldosterone (602 [415, 946] vs. 347 [263, 537] pmol·L-1 ). Urine osmolality was unchanging and related consistently to copeptin at end-exercise, whereas the association between copeptin and serum osmolality was right-shifted (P = 0.0109) with acclimatization. Unchanging urine:serum osmolality argued against increased renal action of vasopressin. In conclusion, where exercise in the heat is performed without fluid replacement, heat acclimatization does not appear to enhance AVP-mediated free water retention in humans.