Validity of combined hydration self-assessment measurements to estimate a low vs. high urine concentration in a small sample of (tactical) athletes.

PURPOSE: Relationships between body weight, urine color (Uc), and thirst level (WUT) have been proposed as a simple and inexpensive self-assessment method to predict dehydration. This study aimed to determine if this method also allowed us to accurately identify a low vs. high urine concentration in (tactical) athletes. METHODS: A total of n = 19 Army Reserve Officer Training Corps cadets and club sports athletes (22.7 ± 3.8 years old, of which 13 male) were included in the analysis, providing morning body weight, thirst sensation, and Uc for five consecutive days. Each item received a score 0 or 1, resulting in a WUT score ranging from 0 (likely hydrated) to 3 (very likely dehydrated). WUT model and individual item outcomes were then compared with a ≥ 1.020 urine specific gravity (USG) cut-off indicating a high urine concentration, using descriptive comparisons, generalized linear mixed models, and logistic regression (to calculate the area under the curve (AUC)). RESULTS: WUT score was not significantly predictive of urine concentration, z = 1.59, p = 0.11. The AUC ranged from 0.54 to 0.77 for test days, suggesting a fair AUC on most days. Only Uc was significantly related to urine concentration, z = 2.49, p = 0.01. The accuracy of the WUT model for correctly classifying urine samples with a high concentration was 68% vs. 51% of samples with a low concentration, resulting in an average accuracy of 61%. CONCLUSION: This study shows that WUT scores were not predictive of urine concentration, and the method did not substantially outperform the accuracy of Uc scoring alone.

A Study of the Fluid Intake, Hydration Status, and Health Effects among Pregnant Women in Their Second Trimester in China: A Cross-Sectional Study.

The fluid intake and hydration status during pregnancy may influence the health outcomes of both the mother and the fetus. However, there are few studies related to this. The aim of the present study was to investigate fluid intake behaviors among pregnant women in their second trimester, to evaluate their hydration status and pregnancy complications, and to further explore the association of fluid intake and the amniotic fluid index (AFI). Participants' total fluid intake (TFI) levels were determined using a 7-day 24 h fluid intake questionnaire. The levels of water intake from food were not recorded or measured. Morning urine samples were collected, and both urine osmolality levels and urine specific gravity (USG) were tested to evaluate their hydration status. Fasting blood samples were also collected and measured for osmolality and complete blood count (CBC). A total of 324 participants completed the study. They were divided into four groups based on quartiles of TFI, including participants with lower (LFI1 and LFI2) and higher (HFI1 and HFI2) fluid intake levels. The median TFI was 1485 mL, and the median values of the four groups with different TFI levels were 1348, 1449, 1530, and 1609 mL, respectively. Only 3.4% of the participants attained the recommended value following an adequate water intake (1.7 L) level for pregnant women in China. Plain water was the main TFI resource (78.8~100.00%), and differences in the plain water intake levels among the four groups were evident (χ2 = 222.027, p < 0.05). The urine osmolality decreased sequentially with increasing TFI values from the LFI1 to HFI2 group, and significant differences in the urine osmolality levels among the four groups were evident (p < 0.05). Meanwhile, the percentage of dehydrated participants decreased from 26.8% in the LFI1 group to 0.0% in the HFI2 group (χ2 = 131.241, p < 0.05). Participants with higher TFI values had higher AFI values (χ2 = 58.386, all p < 0.05), and moderate-intensity correlations were found between TFI and urine osmolality, hydration status, and AFI (all p < 0.05). A large proportion of the participants had insufficient TFIs during the second trimester of pregnancy, and a proportion of the participants were dehydrated. The preliminary analysis showed that the AFI was correlated with the TFI during the second trimester of pregnancy. A sufficient TFI is necessary for pregnant women to improve their hydration status and may have effects on their health. The results can provide appropriate scientific references for the development of beneficial recommendations concerning adequate water intake levels for pregnant women in China.

Comparison between digital and paper urine color to assess hydration status.

PURPOSE: The purpose of this study was to investigate associations between digital urine color and paper urine color with other urine indices to assess hydration status. METHODS: Twelve male subjects (mean ± standard deviation; age, 26 ± 8 years; body mass, 57.8 ± 5.3 kg; height, 177.5 ± 8.9 cm; VO2max, 57.8 ± 5.8 ml·kg-1·min-1) performed four exercise trials in the heat. Before and following exercise trials, subjects provide urine samples. Urine samples were measured using a digital urine color chart on a portable device screen. Urine samples were also assessed with urine specific gravity (USG), urine osmolality (UOsmo), and a validated paper urine color chart. RESULTS: There were extremely large associations found between digital urine color and paper urine color (r = 0.926, p < 0.001). Correlation coefficients showing associations with USG and UOsmo were similar between digital urine color (USG, r = 0.695, p < 0.001; UOsmo, r = 0.555, p < 0.001) and paper urine color (USG, r = 0.713, p < 0.001; UOsmo, r = 0.570, p < 0.001). Bland-Altman analysis indicated that no proportional bias was observed between digital and paper urine colors (bias, - 0.148; SD of bias, 0.492; 95% LOA, - 1.11, 0.817; p = 0.094). CONCLUSIONS: Strong associations were found between digital and paper urine colors with no proportional bias. Furthermore, the degree of associations with USG and UOsmo was similar between digital and paper urine color. These results indicate that digital urine color is a useful tool to assess hydration status and this method could be used as an alternative method to using paper urine color.

Urinary Hydration Biomarkers and Water Sources in Older Adults with Neurocognitive Disorder.

The risk of dehydration in older adults with neurocognitive disorder (NCD) is controversial. The purpose of this study was to assess hydration status, its determinants, and water intake sources in older adults with NCD. A sample of 30 participants (≥60 years) was included. Sociodemographic, clinical data and one 24-h urine sample were collected. Urinary osmolality, sodium, potassium, volume, and creatinine were quantified. Inadequate hydration status corresponded to urine osmolality > 500 mOsm/Kg, or a negative Free Water Reserve (FWR). Two 24-h food recalls were used to assess dietary intake and water sources. The adequacy of total water intake (TWI) was estimated according to EFSA. The contribution of food and beverages to TWI was calculated, and their associations with the urinary osmolality median were tested. Of the total number of participants, 30% were classified as having inadequate hydration status, with no differences between sexes. Regarding TWI, 68.4% of women and 77.8% of men did not reach the reference values. Water (23%), followed by soup (17%), contributed the most to TWI, while vegetables (2%) and alcoholic/other beverages (3%) contributed the least. According to the median urinary osmolality, there was no significant difference in sociodemographic/clinical characteristics. It is critical not to overlook hydration in this vulnerable population.

A burst of fenoterol excretion during the recovery of a weight loss protocol.

Fenoterol is a sympathomimetic ß2 receptor agonist primarily used as a bronchodilator. Due to its sympathomimetic actions, the World Anti-Doping Agency (WADA) has banned it. Multiple acute weight loss protocols (WLP) are used by Olympic athletes for sports that segregate athletes by weight; these generally involve caloric and water deprivation combined with heat exposure. Athletes use WLP before weigh-in, then transition to different body acute weight regain protocols (WRP) before competitions. Here, we studied the pharmacokinetics of fenoterol under WLP conditions: energetic dietary restriction, decreased water intake, and exposure to a dry sauna (80 ± 2 °C), followed by a WRP. Five elite-level female judo athletes participated in the study. Four received fenoterol (200 µg; n = 2 or 400 µg; n = 2), while one was a control receiving placebo under identical conditions. We measured excretion of the fenoterol parent molecule and presented qualitative data of its sulfated metabolite using QqQ tandem quadrupole mass spectrometry for 118 h. The fenoterol parent appeared earlier in urine than did its conjugated metabolite; excretion profiles were similar among all subjects. The centers of mass for fenoterol parent curves were (time, fenoterol): athlete A (10.9, 7.3); athlete B (9.2, 27.3); athlete C (8.5, 6.9); athlete D (9.7, 5.0). After initiating WRP, we observed a burst in urinary fenoterol excretion once in complete decay. This trend was observed for all four athletes who received fenoterol. Our results suggest that during hypohydration, some of the unmetabolized fenoterol accumulates in tissues, then is released during rehydration. These findings can be important for detecting fenoterol use in athletes.

Behaviors of Water Intake, Hydration Status, and Related Hydration Biomarkers among Physically Active Male Young Adults in Beijing, China: A Cross-Sectional Study.

Studies on the water intake of athletes in daily life are insufficient. The objective was to determine the water intake and hydration status among physically active male young adults. In this cross-sectional studies study, 111 physically active male young adults were recruited. The amount of daily total drinking fluid intake (TDF) among participants was recorded and evaluated in real time over 7 days using the "7-day 24-hour fluid intake questionnaire" (liq. In 7). The daily water intake from food (WFF) was calculated using the weighing, duplicate portion, and direct-drying method over 3 days. All urine samples over 3 days were collected, and urine biomarkers were determined. According to 24 h urine osmolality, the participants were divided into three groups with euhydration status, middle hydration, and hypo hydration statuses. Finally, 109 participants completed the study. The median daily total water intake (TWI), TDF, and WFF were 2701, ik1789, and 955 mL, respectively. Among participants, 17 participants (16%) were in euhydration status, 47 participants (43%) were in hypohydration, and 45 participants (41%) were in middle hydration. There were statistical significances in the 24 h urine volume, osmolality, urine specific gravity, and concentrations of K, Na, and Cl in different hydration statuses (χ 2 = 28.212, P < 0.01; χ 2 = 91.341, P < 0.01; χ 2 = 47.721, P < 0.01; χ 2 = 41.548, P < 0.01; χ 2 = 46.863, P < 0.01; and χ 2 = 40.839, P < 0.01). Moderate-intensity correlations were found between the TDF and 24 h urine volume, 24 h urine osmolality, 24 h urine Na concentration, morning urine osmolality, and morning urine Na concentration (r = 0.408, P < 0.01; r = -0.378, P < 0.01; r = -0.325, P < 0.01; r = -0.344, P < 0.01; and r = -0.329, P < 0.01). There were also moderate-intensity correlations between the TDF and 24 h urine osmolality, morning urine osmolality, and morning urine Na concentration (r = -0.365, P < 0.01; r = -0.371, P < 0.01; and r = -0.322, P = 0.01). Increased and higher moderate-intensity correlations were found between plain water and 24 h urine volume, 24 h urine osmolality, 24 h urine K and Na concentration, morning urine osmolality, and morning urine Na concentration (r = 0.374, P < 0.01; r = -0.520, P < 0.01; r = -0.312,P < 0.01; r = -0.355, P < 0.01; r = -0.446, P < 0.01; and r = -0.378, P < 0.01). Insufficient water intake and hypohydration were common among physically active male young adults. The amount and type of water intake were correlated with hydration status and urine biomarkers. The results could provide scientific and accurate references for the development of recommendations on water intake for athletes.

Evaluation and education of hydration and sodium status in a cool environment among Chinese athletes.

OBJECTIVE: The aim of the study was to find the significance of several factors with parameters of urine tests and blood tests. Finally, we aimed at evaluating the percentage of athletes from the study sample regarding their hydration level. SUBJECTS AND METHODS: The current study is the prospective type and was conducted on Chinese athletes between June 2021 to April 2022. The study was done in 2 parts for obtaining measurements in the summer season and the winter season and then they were correlated between them. Urine and blood samples were evaluated for determining the required parameters. The parameters of the physical environment like temperature, relative humidity, precipitation, etc. were obtained from the concerned weather station for each day. RESULTS: It was observed that 14.5%, 59% and 26.5% of the female participants were found to have hyper-hydrated, euhydrated and dehydrated, respectively. While 17.57%, 69.69% and 12.74% of the males were classified as hyper-hydrated, euhydrated and dehydrated, respectively. The participants with hyper-hydrated were found to have increased urine volume (p<0.001), reduced specific gravity (p<0.001) and reduced-sodium level (p<0.001). CONCLUSIONS: The study found that there is a significant difference in sodium levels between gender and seasons. The level of serum osmolality is also significantly different between the whole study populations concerning combined seasons. In this way, many other parameters are evaluated by correlation with seasons and gender. Hence, this study has brought forward various important findings and gives an overall evaluation of hydration status.

Dehydration Status Aggravates Early Renal Impairment in Children: A Longitudinal Study.

Dehydration is common in children for physiological and behavioral reasons. The objective of this study was to assess changes in hydration status and renal impairment across school weekdays. We conducted a longitudinal study of three repeated measures of urinalysis within one week in November 2019 in a child cohort in Beijing, China. We measured urine specific gravity (USG) to determine the dehydration status, and the concentration of ß2-microglobulin (ß2-MG) and microalbumin (MA) to assess renal function impairment among 1885 children with a mean age of 7.7 years old. The prevalence of dehydration was 61.9%, which was significantly higher in boys (64.3%). Using chi-square tests and linear mixed-effects regression models, we documented the trends of the renal indicators' change over time among different hydration statuses. Compared to Mondays, there were apparent increases of ß2-MG concentrations on Wednesdays (ß = 0.029, p < 0.001) and Fridays (ß = 0.035, p < 0.001) in the dehydrated group, but not in the euhydrated group. As for the MA concentrations, only the decrease on Fridays (ß = -1.822, p = 0.01) was significant in the euhydrated group. An increased trend of elevated ß2-MG concentration was shown in both the euhydrated group (Z = -3.33, p < 0.001) and the dehydrated group (Z = -8.82, p < 0.001). By contrast, there was a decreased trend of elevated MA concentrations in the euhydrated group (Z = 3.59, p < 0.001) but not in the dehydrated group. A new indicator ratio, ß2-MG/MA, validated the consistent trends of renal function impairment in children with dehydration. Renal impairment trends worsened as a function of school days during the week and the dehydration status aggravated renal impairment during childhood across school weekdays, especially tubular abnormalities in children.

Relationships Between WUT (Body Weight, Urine Color, and Thirst Level) Criteria and Urine Indices of Hydration Status.

BACKGROUND: A Venn diagram consisting of percentage body mass loss, urine color, and thirst perception (weight, urine, thirst [WUT]) has been suggested as a practical method to assess hydration status. However, no study to date has examined relationships between WUT and urine hydration indices. Thus, the purpose of this study was to investigate relationships between urine specific gravity, urine osmolality, and the WUT criteria. HYPOTHESIS: Urine specific gravity and urine osmolality indicate hypohydration when the WUT criteria demonstrate hypohydration (≥2 markers). STUDY DESIGN: Laboratory cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 22 women (mean ± SD; age, 20 ± 1 years; mass, 65.4 ± 12.6 kg) and 21 men (age, 21 ± 1 years; body mass, 78.7 ± 14.6 kg) participated in this study. First morning body mass, urine color, urine specific gravity, urine osmolality, and thirst level were collected for 10 consecutive days in a free-living situation. Body mass loss >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels were counted and categorized into either 3, 2, 1, or 0 WUT markers that indicated dehydration. One-way analysis of variance with Tukey pairwise comparisons was used to assess the differences in urine specific gravity and urine osmolality between the different number of WUT markers. RESULTS: Urine specific gravity in 3 WUT markers (mean ± SD [effect size], 1.021 ± 0.007 [0.57]; P = 0.025) and 2 WUT markers (1.019 ± 0.010 [0.31]; P = 0.026) was significantly higher than 1 WUT marker (1.016 ± 0.009). Urine mosmolality in 2 WUT markers (705 ± 253 mOsmol [0.43]; P = 0.018) was significantly higher than 1 WUT (597 ± 253 mOsmol). Meeting at 3 WUT resulted in specificity of 0.956 and at 0 WUT resulted in sensitivity of 0.937 for urine osmolality>700mOsm. CONCLUSION: These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality indicated hypohydration and 0 WUT represents a high likelihood of euhydration. 1 and 2 WUT values are indeterminate of hydration status. The WUT criterion is a useful tool to use in field settings to assess hydration status when first morning urine sample was used. CLINICAL RELEVANCE: Athletes, coaches, sports scientists, and medical professionals can use WUT criteria to monitor dehydration with reduced cost and time.

The Relationships between Water Intake and Hydration Biomarkers and the Applications for Assessing Adequate Total Water Intake among Young Adults in Hebei, China.

Water is an essential nutrient for humans. A cross-sectional study was conducted among 159 young adults aged 18-23 years in Hebei, China. The total drinking fluids and water from food were obtained by 7-day 24 h fluid intake questionnaires and the duplicate portion method, respectively. Pearson's correlation coefficients were performed to determine the relationship between fluid intake and 24 h urinary biomarkers and plasma biomarkers. A multivariable partial least squares (PLS) model was used to identify the key predictors in modeling the total water intake (TWI) with 24 h urine biomarkers. Logistic regressions of the TWI against binary variables were performed, and the receiver operating characteristic curve (ROC) was analyzed to determine the cutoff value of the TWI for the optimal hydration status and dehydration without adjustments to favor either the sensitivity or specificity. In total, 156 participants (80 males and 76 females) completed the study. Strong relationships were found between the total drinking fluids, TWI, and 24 h urine biomarkers among young adults, especially for the 24 h urine volume (r = 0.784, p < 0.001; r = 0.747, p < 0.001) and osmolality (r = -0.589, p < 0.001; r = -0.477, p < 0.001), respectively. As for the FMU and plasma biomarkers, no strong relationships were found. The percentages of the variance in TWI explained by the PLS model with 13 urinary biomarkers were 66.9%. The optimal TWI values for assessing the optimal hydration and dehydration were 2892 mL and 2482 mL for young males, respectively, and 2139 mL and 1507 mL for young females, respectively. Strong relationships were found between the TWI, total drinking fluids, and 24 h urine biomarkers, but not with the FMU and plasma biomarkers, among young adults, including males and females. The 24 h urine biomarkers were more sensitive than the first morning urinary biomarkers in reflecting the fluid intake. The TWI was a reliable index for assessing the hydration statuses for young adults in free-living conditions.

Availability of a Flavored Beverage and Impact on Children's Hydration Status, Sleep, and Mood.

Euhydration remains a challenge in children due to lack of access and unpalatability of water and to other reasons. The purpose of this study was to determine if the availability/access to a beverage (Creative Roots®) influences hydration in children and, therefore, sleep quality and mood. Using a crossover investigation, 46 participants were randomly assigned to a control group (CON) or an intervention group and received Creative Roots® (INT) for two-week periods. We recorded daily first morning and afternoon urine color (Ucol), thirst perception, and bodyweight of the two groups. Participants reported to the lab once per week and provided first morning urine samples to assess Ucol, urine specific gravity (USG), and urine osmolality (Uosmo). Participants also completed the questionnaires Profile of Mood States-Adolescents (POMS-a) and Pittsburgh Sleep Quality Index (PSQI). Dependent t-tests were used to assess the effects of the intervention on hydration, mood, and sleep quality. Uosmo was greater and Ucol was darker in the control group (mean ± SD) [Uosmo: INT = 828 ± 177 mOsm·kg-1, CON = 879 ± 184 mOsm·kg-1, (p = 0.037], [Ucol:INT = 5 ± 1, CON = 5 ± 1, p = 0.024]. USG, POMS-a, and PSQI were not significant between the groups. At-home daily afternoon Ucol was darker in the control group [INT = 3 ± 1, CON = 3 ± 1, p = 0.022]. Access to Creative Roots® provides a small, potentially meaningful hydration benefit in children. However, children still demonstrated consistent mild dehydration based on Uosmo, despite consuming the beverage.

[Analysis of dehydration in older people in a nursing home in Spain: prevalence and associated factors]. / Análisis de la deshidratación de adultos mayores en una residencia geriátrica de España: prevalencia y factores asociados.

INTRODUCTION: Background: dehydration in institutionalized elderly people has not been extensively studied. There are not clear data on the Spanish context. Aim: to estimate the prevalence of dehydration and to identify the associated factors in institutionalized older people in a nursing home. Methods: a cross-sectional study was carried out. Dehydration was measured through the colour of urine. For the identification of the associated factors, sociodemographic, clinical, functional, and mental variables were selected. Results: the total sample studied was comprised of 96 individuals with a mean age of 86.6 years (± 7.1), of whom 80.2 % were women. The prevalence of dehydration was 31.3% (95 % CI, 22.0 to 40.6). The factors that were independently associated with dehydration were the presence of sunken eyes (OR = 8.67; p = 0.004), low fluid intake (OR = 3.96; p = 0.041), and both functional (OR = 0.97; p = 0.012) and cognitive (OR = 1.10; p = 0.009) impairment. Conclusions: this study highlights the problem of dehydration in institutionalized older people in Spain. An urine colour table may be used routinely, non-invasively, and cheaply. So, it may well be the best simple method for detecting dehydration in this population. Taking into account that chronic dehydration is most prevalent in elderly people, the identification of associated factors is a key factor for a successful approach.

INTRODUCCIÓN: Introducción: la deshidratación en las personas mayores institucionalizadas es un problema poco explorado, no habiéndose encontrado evidencia al respecto en relación con las personas mayores del contexto residencial español. Objetivos: estimar la prevalencia de la deshidratación e identificar los factores asociados a la misma en las personas mayores institucionalizadas en una residencia geriátrica. Métodos: estudio descriptivo y transversal. La deshidratación se midió a través del color de la orina. Para la identificación de los factores se seleccionaron variables sociodemográficas, clínicas, funcionales y mentales. Resultados: la muestra total estudiada fue de 96 individuos con una media de edad de 86,6 años (± 7,1), de los cuales el 80,2 % eran mujeres. La prevalencia de la deshidratación fue del 31,3 % (IC 95 %: 22,0 a 40,6). Los factores que se asociaron independientemente a la deshidratación fueron la presencia de ojos hundidos (OR = 8,67; p = 0,004), la baja ingesta hídrica (OR = 3,96; p = 0,041) y el deterioro funcional (OR = 0,97; p = 0,012) y cognitivo (OR = 1,10; p = 0,009). Conclusiones: este estudio permite visibilizar el problema de la deshidratación en las personas mayores institucionalizadas en España. La tabla de colores de la orina puede emplearse de forma rutinaria, no invasiva y con bajo coste, por lo que podría ser el método de elección para la detección de la deshidratación en esta población. Teniendo en cuenta que la deshidratación crónica es la más prevalente en las personas mayores, la identificación de los factores asociados es clave para mejorar su hidratación.

Assessing dehydration status in dengue patients using urine colourimetry and mobile phone technology.

BACKGROUND: Dengue is a systemic and dynamic disease with symptoms ranging from undifferentiated fever to dengue shock syndrome. Assessment of patients' severity of dehydration is integral to appropriate care and management. Urine colour has been shown to have a high correlation with overall assessment of hydration status. This study tests the feasibility of measuring dehydration severity in dengue fever patients by comparing urine colour captured by mobile phone cameras to established laboratory parameters. METHODOLOGY/PRINCIPAL FINDINGS: Photos of urine samples were taken in a customized photo booth, then processed using Adobe Photoshop to index urine colour into the red, green, and blue (RGB) colour space and assigned a unique RGB value. The RGB values were then correlated with patients' clinical and laboratory hydration indices using Pearson's correlation and multiple linear regression. There were strong correlations between urine osmolality and the RGB of urine colour, with r = -0.701 (red), r = -0.741 (green), and r = -0.761 (blue) (all p-value <0.05). There were strong correlations between urine specific gravity and the RGB of urine colour, with r = -0.759 (red), r = -0.785 (green), and r = -0.820 (blue) (all p-value <0.05). The blue component had the highest correlations with urine specific gravity and urine osmolality. There were moderate correlations between RGB components and serum urea, at r = -0.338 (red), -0.329 (green), -0.360 (blue). In terms of urine biochemical parameters linked to dehydration, multiple linear regression studies showed that the green colourimetry code was predictive of urine osmolality (ß coefficient -0.082, p-value <0.001) while the blue colourimetry code was predictive of urine specific gravity (ß coefficient -2,946.255, p-value 0.007). CONCLUSIONS/SIGNIFICANCE: Urine colourimetry using mobile phones was highly correlated with the hydration status of dengue patients, making it a potentially useful hydration status tool.

Racial and Sex Differences in 24 Hour Urinary Hydration Markers among Male and Female Emerging Adults: A Pilot Study.

The purpose of this study was to examine 24 h urinary hydration markers in non-Hispanic White (WH) and non-Hispanic Black (BL) males and females. Thirteen males (BL, n = 6; WH, n = 7) and nineteen females (BL, n = 16, WH, n = 3) (mean ± SD; age, 20 ± 4 y; height, 169.2 ± 12.2 cm; body mass, 71.3 ± 12.2 kg; body fat, 20.8 ± 9.7%) provided a 24 h urine sample across 7 (n = 13) or 3 (n = 19) consecutive days (148 d total) for assessment of urine volume (UVOL), urine osmolality (UOSM), urine specific gravity (USG), and urine color (UCOL). UVOL was significantly lower in BL (0.85 ± 0.43 L) compared to WH college students (2.03 ± 0.70 L) (p < 0.001). Measures of UOSM, USG, and UCOL, were significantly greater in BL (716 ± 263 mOsm∙kg-1, 1.020 ± 0.007, and 4.2 ± 1.4, respectively) compared to WH college students (473 ± 194 mOsm∙kg-1, 1.013 ± 0.006, 3.0 ± 1.2, and respectively) (p < 0.05). Differences in 24 h urinary hydration measures were not significantly different between males and females (p > 0.05) or between the interaction of sex and race/ethnicity (p > 0.05). Non-Hispanic Black men and women were inadequately hydrated compared to their non-Hispanic White counterparts. Our findings suggest that development of targeted strategies to improve habitual fluid intake and potentially overall health are needed.

Are hypohydrated older adults at increased risk of exhaustion?

BACKGROUND: Dehydration appears to affect muscle strength and weakness, although its influence on exhaustion remains unclear. The present study aimed to quantify the association between hydration status and exhaustion among older adults. METHODS: A cluster sampling approach was used, representing Portuguese older adults (≥65 years) according to age, sex, education level and region within the Nutrition UP65 cross-sectional study. A 24-h urine sample was collected to estimate free water reserve (FWR), which was categorised into tertiles according to sex. Subjects with incomplete 24-h urine and renal disease were excluded. From a sample size of 1500 subjects, 1143 were eligible. Exhaustion was self-reported according to the Center for Epidemiologic Studies Depression Scale. A logistic regression model was conducted to evaluate the association between FWR and exhaustion. Odds ratios and the respective 95% confidence intervals were calculated by sex and age. RESULTS: Free water reserve median (interquartile range) was 0.52 (0.68) L in women and 0.36 (0.77) L in men. Hypohydration affected 11.6% of women and 25.1% of men, whereas exhaustion was reported by 39.3% of women and 25.1% of men. After adjusting for confounders, women ≥80 years classified in the highest tertile of FWR showed a decreased risk of exhaustion (third tertile: odds ratio = 0.38; 95% confidence interval = 0.15-0.96) compared to women in the lowest FWR tertile. No such significant association was observed in women with <80 years and in men. CONCLUSIONS: These results show an association between worse hydration status and exhaustion in older women, highlighting the need to implement further studies clarifying this association.

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.

Smartphone-Based Analysis of Urine Reagent Strips Is Inaccurate for Assessing Underhydration.

Background: Proper hydration is vital for both exercise and general health. Although various methods for hydration assessment exist, many are not valid for either use or never tested. Introduction: The purpose of this study was to determine whether the uChek© smart phone application can be used to diagnose underhydration based on elevated urine specific gravity (USG) assessed by refractometry. Methods: One hundred forty-seven (n = 147) fresh human urine samples from young and middle-age adults were analyzed for USG with a refractometer and the uChek© application by reading the Siemens Multistix 10G urine reagent strip. Results: Bland-Altman analysis showed agreement of the two methods of assessment. Overall diagnostic ability of the uChek© to identify underhydration was fair (area under the curve 79%). However, the sensitivity to correctly identify underhydration was poor (60%) as well as the specificity of correctly identifying euhydration (53%). Conclusion: The uChek© application does not accurately detect underhydration.

The Relationship between %BML, Urine Color, Thirst Level and Urine Indices of Hydration Status.

INTRODUCTION: Dehydration is known to impair health, quality of daily life, and exercise performance [1]. While several methods are utilized to assess fluid balance, there is no gold standard to assess hydration status [2]. Cheuvront and Kenefick [3] suggested the use of a Venn diagram, which consists of % body mass weight (BML), urine color, and thirst level (WUT) to measure hydration status and fluid needs. However, no study to date has examined the relationship between the WUT criteria and hydration status measured by urine indices. OBJECTIVE: The purpose of this study was to investigate the relationships between urine-specific gravity (USG), urine osmolality (UOSM), and the WUT criteria. METHODS: Twenty-two females (mean ± SD; age, 20 ± 1 year; weight, 65.4 ± 12.6 kg) and twenty-one males (age, 21 ± 1 year; body mass, 78.7 ± 14.6 kg) participated in this study. First-morning body mass, urine color, USG, UOSM, and thirst level were collected for 10 consecutive days. First 3 days were utilized to establish a euhydrated baseline body weight. %BML >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels was summed when each variable met each threshold. One-way ANOVA with Tukey pairwise comparison was used to assess the differences in USG and UOSM, followed by a calculation of effect size (ES). RESULTS: Figure 1 indicates the differences of UOSM based on the WUT criteria. For UOSM, "2 markers indicated" (mean [M] ± SD [ES], 705 ± 253 mOsmol [0.43], p = 0.018) was significantly higher than "1 marker indicated" (M ± SD, 597 ± 253 mOsmol). Additionally, "zero marker indicated" (509 ± 249 mOsmol) was significantly lower than "3 markers indicated" (M ± SD [ES], 761 ± 250 mOsmol, [1.01], p = 0.02) and "2 markers indicated" ([ES], [0.78], p = 0.004). However, there was no statistical difference between "3 markers indicated" ([ES], [0.65], p = 0.13) and "1 marker indicated." For USG, "3 markers indicated" (M ± SD [ES], 1.021 ± 0.007 [0.57], p = 0.025) and "2 markers indicated" (M ± SD [ES], 1.019 ± 0.010 [0.31], p = 0.026) were significantly higher than "1 marker indicated" (M ± SD, 1.016 ± 0.009). Additionally, "zero marker indicated" (1.014 ± 0.005) was significantly lower than "3 markers indicated" ([ES], [1.21], p = 0.005) and "2 markers indicated" ([ES], [0.54], p = 0.009). CONCLUSION: When 3 markers indicated dehydration levels, UOSM and USG were greater than euhydrated cut points. When 2 markers indicated dehydration levels, USG was higher than the euhydrated cut point. Additionally, UOSM and USG were significantly lower when zero or 1 marker indicated dehydration levels. Thus, the WUT criteria are a useful tool to assess hydration status. Athletes, coaches, sports scientists, and medical professions can use this strategy in the field settings to optimize their performance and health without consuming money and time.

Effects of a 14-Day Hydration Intervention on Individuals with Habitually Low Fluid Intake.

BACKGROUND: Debate continues over whether or not individuals with low total water intake (TWI) are in a chronic fluid deficit (i.e., low total body water) [1]. When women with habitually low TWI (1.6 ± 0.5 L/day) increased their fluid intake (3.5 ± 0.1 L/day) for 4 days 24-h urine osmolality decreased, but there was no change in body weight, a proxy for total body water (TBW) [2]. In a small (n = 5) study of adult men, there were no observable changes in TBW, as measured by bioelectrical impedance, after increasing TWI for 4 weeks [3]. However, body weight increased and salivary osmolality decreased indicating that the study may have been underpowered to detect changes in TBW. Further, no studies to date have measured changes in blood volume (BV) when TWI is increased. OBJECTIVES: Therefore, the purpose of this study was to identify individuals with habitually low fluid intake and determine if increasing TWI, for 14 days, resulted in changes in TBW or BV. METHODS: In order to identify individuals with low TWI, 889 healthy adults were screened. Participants with a self-reported TWI less than 1.8 L/day (men) or 1.2 L/day (women), and a 24-h urine osmolality greater than 800 mOsm were included in the intervention phase of the study. For the intervention phase, 15 participants were assigned to the experimental group and 8 participants were assigned to the control group. The intervention period lasted for 14 days and consisted of 2 visits to our laboratory: one before the intervention (baseline) and 14 days into the intervention (14-day follow-up). At these visits, BV was measured using a CO-rebreathe procedure and deuterium oxide (D2O) was administered to measure TBW. Urine samples were collected immediately prior, and 3-8 h after the D2O dose to allow for equilibration. Prior to each visit, participants collected 24-h urine to measure 24-h hydration status. After the baseline visit, the experimental group increased their TWI to 3.7 L for males and 2.7 L for females in order to meet the current Institute of Medicine recommendations for TWI. RESULTS: Twenty-four-hour urine osmolality decreased (-438.7 ± 362.1 mOsm; p < 0.001) and urine volume increased (1,526 ± 869 mL; p < 0.001) in the experimental group from baseline, while there were no differences in osmolality (-74.7 ± 572 mOsm; p = 0.45), or urine volume (-32 ± 1,376 mL; p = 0.89) in the control group. However, there were no changes in BV (Fig. 1a) or changes in TBW (Fig. 1b) in either group. CONCLUSIONS: Increasing fluid intake in individuals with habitually low TWI increases 24-h urine volume and decreases urine osmolality but does not result in changes in TBW or BV. These findings are in agreement with previous work indicating that TWI interventions lasting 3 days [2] to 4 weeks [3] do not result in changes in TBW. Current evidence would suggest that the benefits of increasing TWI are not related changes in TBW.

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.