The Validity of Urine Color as a Hydration Biomarker within the General Adult Population and Athletes: A Systematic Review.

Frequent monitoring of hydration status may help to avoid the adverse effects of dehydration. Other than urine color assessment, hydration assessment methods are largely impractical for the general population and athletes to implement on a routine basis. Despite its widespread use, the validity of urine color as an indicator of hydration status has not been systematically evaluated. The objective of this systematic review is to determine the validity of urine color evaluation as a hydration status assessment method in the general adult population, older adults, and athletes. Using the PRISMA guidelines, electronic databases were searched to identify original research articles of all study design types for inclusion. Of the 424 articles screened, 10 met inclusion criteria. Most studies compared urine color to either urinary specific gravity or urine osmolality, and reported significant associations (r) ranging from 0.40 to 0.93. Lower correlations were noted in studies of adults aged >60 years. Studies generally reported a high sensitivity of urine color as a diagnostic tool for detecting dehydration and supported the ability of this method to distinguish across categories of hydration status. Research is needed to determine if clinicians, patients, and clients can accurately utilize this method in clinical and real-world settings. Future research is also needed to extend these findings to other populations, such as children.Key teaching pointsInadequate hydration can lead to impairments in physical performance and cognitive function.Methods used to assess hydration status include plasma/serum osmolality, urinary specific gravity (USG), urine osmolality (Uosm), change in body weight, urine volume, and urine color.Urine color assessment is a practical method that is routinely used in clinical, athletic, and other settings. The validity of this method has not been systemically evaluated.Available research was limited to 10 articles.Validity of this method was generally supported; however, research has not investigated the validity of this method by clinicians, patients and clients.

Evaluation of Pragmatic Methods to Rapidly Assess Habitual Beverage Intake and Hydration Status in U.S. Collegiate Athletes.

Fluid intake recommendations have been established for the athletic population in order to promote adequate hydration. The Beverage Intake Questionnaire (BEVQ-15) is a quick and reliable food frequency questionnaire that quantifies habitual beverage intake, which has been validated in children, adolescents, and adults. However, no validated beverage consumption questionnaire is available for collegiate athletes. Urine color (UC), while feasible for determining hydration status, has not been validated within a variety of collegiate athletes. The purpose of this investigation was to evaluate the comparative validity and reliability of pragmatic methods to rapidly assess BEVQ-15 and UC rating in U.S. Division I collegiate athletes. Student-athletes (n = 120; 54% females; age 19 ± 1 years) from two universities were recruited to complete three study sessions. At the first and third sessions, the participants completed the BEVQ-15 and provided a urine sample to determine UC and urinary specific gravity. All sessions included completion of a 24-hr dietary recall. Total fluid intake (fl oz) was 111 ± 107 and 108 ± 42 using the BEVQ-15 and the mean of three 24-hr dietary recalls, respectively, which was not different between methods (p > .05). There were moderate associations between the BEVQ-15 and dietary recall results for total beverage intake fl oz and kcal(r = .413 and r = 4.65; p ≤ .05, respectively). Strong associations were noted between both researcher-rated and participant-rated UC with urinary specific gravity measures (r = .675 and r = .884; p ≤ .05, respectively). Therefore, these rapid assessment methods demonstrated acceptable validity and may be used as practical methods to determine whether athletes are meeting their hydration recommendations.

Urinary markers of hydration during 3-day water restriction and graded rehydration.

PURPOSE: This investigation had three purposes: (a) to evaluate changes in hydration biomarkers in response to a graded rehydration intervention (GRHI) following 3 days of water restriction (WR), (b) assess within-day variation in urine concentrations, and (c) quantify the volume of fluid needed to return to euhydration as demonstrated by change in Ucol. METHODS: 115 adult males and females were observed during 1 week of habitual fluid intake, 3 days of fluid restriction (1000 mL day-1), and a fourth day in which the sample was randomized into five different GRHI groups: no additional water, CON; additional 500 mL, G+0.50; additional 1000 mL, G+1.00; additional 1500 mL, G+1.50; additional 2250 mL, G+2.25. All urine was collected on 1 day of the baseline week, during the final 2 days of the WR, and during the day of GRHI, and evaluated for urine osmolality, color, and specific gravity. RESULTS: Following the GRHI, only G+1.50 and G+2.25 resulted in all urinary values being significantly different from CON. The mean volume of water increase was significantly greater for those whose Ucol changed from > 4 to < 4 (+ 1435 ± 812 mL) than those whose Ucol remained ≥ 4 (+ 667 ± 722 mL, p < 0.001). CONCLUSIONS: An additional 500 mL of water is not sufficient, while approximately 1500 mL of additional water (for a total intake between 2990 and 3515 mL day-1) is required to return to a urine color associated with adequate water intake, following 3 days of WR.

Signs of Dehydration after Hip Fracture Surgery: An Observational Descriptive Study.

Background and Objectives: Dehydration might be an issue after hip fracture surgery, but the optimal tools to identify the dehydrated condition have not been determined. The aim of the present study was to compare the characteristics of elderly postoperative patients who were classified as dehydrated according to the methods used in the clinic. Materials and Methods: Thirty-eight patients aged between 65 and 97 (mean, 82) years were studied after being admitted to a geriatric department for rehabilitation after hip fracture surgery. Each patient underwent blood analyses, urine sampling, and clinical examinations. Results: Patients ingested a mean of 1,008 mL (standard deviation, 309 mL) of fluid during their first day at the clinic. Serum osmolality increased significantly with the plasma concentrations of sodium, creatinine, and urea. Seven patients had high serum osmolality (≥300 mosmol/kg) that correlated with the presence of tongue furrows (p < 0.04), poor skin turgor (p < 0.03), and pronounced albuminuria (p < 0.03). Eight patients had concentrated urine (urine-specific gravity ≥ 1.025) that correlated with a low intake of liquid and with a decrease in body weight during the past month of -3.0 kg (25-75 th percentiles, -5.1 to -0.9) versus +0.2 (-1.9 to +2.7) kg (p < 0.04). Conclusions: Renal fluid conservation of water, either in the form of hyperosmolality or concentrated urine, was found in 40% of the patients after hip fracture surgery. Hyperosmolality might not indicate a more severe fluid deficit than is indicated by concentrated urine but suggests an impaired ability to concentrate the urine.

Urine color as an indicator of urine concentration in pregnant and lactating women.

AIM: Urine concentration measured via osmolality (U OSM) and specific gravity (U SG) reflects the adequacy of daily fluid intake, which has important relationships to health in pregnant (PREG) and lactating (LACT) women. Urine color (U COL) may be a practical, surrogate marker for whole-body hydration status. PURPOSE: To determine whether U COL was a valid measure of urine concentration in PREG and LACT, and pair-matched non-pregnant, non-lactating control women (CON). METHODS: Eighteen PREG/LACT (age 31 ± 1 years, pre-pregnancy BMI 24.3 ± 5.9 kg m-2) and eighteen CON (age 29 ± 4 years, BMI 24.1 ± 3.7 kg m-2) collected 24-h and single-urine samples on specified daily voids at five time points (15 ± 2, 26 ± 1, and 37 ± 1 weeks gestation, 3 ± 1 and 9 ± 1 weeks postpartum during lactation; CON visits were separated by similar time intervals) for measurement of 24-h U OSM, U SG, and U COL and single-sample U OSM and U COL. RESULTS: Twenty-four-hour U COL was significantly correlated with 24-h U OSM (r = 0.6085-0.8390, P < 0.0001) and 24-h U SG (r = 0.6213-0.8985, P < 0.0001) in all groups. A 24-h U COL ≥ 4 (AUC = 0.6848-0.9513, P < 0.05) and single-sample U COL ≥ 4 (AUC = 0.9094-0.9216, P < 0.0001) indicated 24-h U OSM ≥ 500 mOsm kg-1 (representing inadequate fluid intake) in PREG, LACT, and CON. CONCLUSIONS: Urine color was a valid marker of urine concentration in all groups. Thus, PREG, LACT, and CON can utilize U COL to monitor their daily fluid balance. Women who present with a U COL ≥ 4 likely have a U OSM ≥ 500 mOsm kg-1 and should increase fluid consumption to improve overall hydration status.

Assessing a Tool for Self-Monitoring Hydration Using Urine Color in Pregnant and Breastfeeding Women: A Cross-Sectional, Online Survey.

BACKGROUND: Pregnant and breastfeeding women experience great changes in their total body water content and water dynamics. To support the accretion of total body water during pregnancy and compensate for the water lost through breast milk during breastfeeding, increased adequate intakes (AI) for total water have been established by various health authorities. Despite this widespread advice, several studies suggest that pregnant and breastfeeding women do not meet the AI for total water, suggesting the need to raise women's awareness on the importance of adequate water intake, particularly during pregnancy and breastfeeding, as well as to provide them with a simple means of monitoring their hydration on a day-to-day basis. A urine color (UC) scale recently has been validated for hydration monitoring in pregnant and breastfeeding women. SUMMARY: We sought to develop a version of a tool based on the UC scale, using only images or illustrations, which could be understood by users of various nationalities and spoken languages. Pregnant and breastfeeding women (n = 1,275) from Brazil, Mexico, and Poland were shown 3 versions of the tool. Understanding, appreciation, simplicity and intent to use were evaluated using a questionnaire consisting of 26 items. Key Messages: Among the 3 versions tested, one tool emerged as the most highly understood (88% spontaneous understanding) and was highly appreciated by users (mean [SD]: 8.40 [2.20] out of 10). There were no differences between countries. Furthermore, 83% reported being very likely to use the tool daily. These results suggest that a simple tool based on the UC scale will help pregnant and breastfeeding women meet the AI for total water.

Fluid Retention and Utility of Practical Hydration Markers to Detect Three Levels of Recovery Fluid Intake in Male Runners.

Runners are unlikely to consume fluid during training bouts increasing the importance of recovery rehydration efforts. This study assessed urine specific gravity (USG) responses following runs in the heat with different recovery fluid intake volumes. Thirteen male runners completed 3 evening running sessions resulting in approximately 2,200 ± 300 ml of sweat loss (3.1 ± 0.4% body mass) followed by a standardized dinner and breakfast. Beverage fluid intake (pre/postbreakfast) equaled 1,565/2,093 ml (low; L), 2,065/2,593 ml (moderate; M) and 2,565/3,356 mL (high; H). Voids were collected in separate containers. Increased urine output resulted in no differences (p > .05) in absolute mean fluid retention for waking or first postbreakfast voids. Night void averages excluding the first void postrun (1.025 ± 0.008; 1.013 ± 0.008; 1.006 ± 0.003), first morning (1.024 ± 0.004; 1.015 ± 0.005; 1.014 ± 0.005), and postbreakfast (1.022 ± 0.007; 1.014 ± 0.007; 1.008 ± 0.003) USG were higher (p < .05) for L versus M and H respectively and more clearly differentiated fluid intake volume between L and M than color or thirst sensation. Waking (r = -0.66) and postbreakfast (r = -0.71) USG were both significantly correlated (p < .001) with fluid replacement percentage, but not absolute fluid retention. Fluid intake M was reported as most similar to normal consumption (5.6 ± 1.0 on 0-10 scale) after breakfast and equaled 122 ± 16% of sweat losses. Retention data suggests consumption above this level is not warranted or actually practiced by most runners drinking ad libitum, but that periodic prerun USG assessment may be useful for coaches to detect runners that habitually consume low levels of fluids between training bouts in warm seasons.

The Effect of Storing Temperature and Duration on Urinary Hydration Markers.

The purpose of this investigation was to quantify the effects of storage temperature, duration, and the urinary sediment on urinary hydration markers. Thirty-six human urine samples were analyzed fresh and then the remaining sample was separated into 24 separate vials, six in each of the following four temperatures: 22 °C, 7 °C, -20 °C, and -80 °C. Two of each sample stored in any given temperature, were analyzed after 1, 2, and 7 days either following vortexing or centrifugation. Each urine sample was analyzed for osmolality (UOsm), urine specific gravity (USG), and urine color (UC). UOsm was stable at 22 °C, for 1 day (+5-9 mmol∙kg-1, p > .05) and at 7 °C, UOsm up to 7 days (+8-8 mmol∙kg-1, p > .05). At -20 and -80 °C, UOsm decreased after 1, 2, and 7 days (9-61 mmol∙kg-1, p < .05). Vortexing the sample before analysis further decreased only UOsm in the -20 °C and -80 °C storage. USG remained stable up to 7 days when samples were stored in 22 °C or 7 °C (p > .05) but declined significantly when stored in -20 °C, and -80 °C (p < .001). UC was not stable in any of the storing conditions for 1, 2, and 7 days. In conclusion, these data indicate that urine specimens analyzed for UOsm or USG remained stable in refrigerated (7 °C) environment for up to 7 days, and in room temperature for 1 day. However, freezing (-20 and -80 °C) samples significantly decreased the values of hydration markers.

Storing urine samples with moisture preserves urine hydration marker stability up to 21 days.

INTRODUCTION: To assess hydration status, hydration markers [urine color, osmolality, and urine-specific gravity (USG)] are used. Urine color, osmolality, and USG have shown to be stable for 7, 7, and 3 days, respectively, at 4 °C. However, refrigeration could produce a dry environment which enhances evaporation and potentially affects urine hydration markers. PURPOSE: To examine the effect of duration and moisture on urine markers with refrigeration. METHODS: 24 participants provided urine samples between 9 and 10 AM. Urine color, osmolality, and USG were analyzed within 2 h (baseline). Then, each urine sample was divided into two urine cups and placed in a storage container with (moisture condition) and without (no moisture condition) water bath at 3 °C. Hydration markers were analyzed at day 1(D1), D2, D7, D10, D14, and D21. A two-way ANOVA (time x condition) and repeated-measures ANOVA on time were performed to examine differences. RESULTS: No significant (p > 0.05) condition x time effect was observed for urine color (p = 0.363), urine osmolality (p = 0.358), and USG (p = 0.248). When urine samples were stored in moisture condition, urine color (p = 0.126) and osmolality (p = 0.053) were stable until D21, while USG was stable until D2 (p = 0.394). CONCLUSION: When assessing hydration status, it appears that the urine color and osmolality were stable for 21 days, while USG was stable for 2 days when stored with moisture at 3 °C. Our results provide guidelines for practitioners regarding urine storage duration and conditions when urine cannot be analyzed immediately.

Hemolysis Precedes Urine Color Change in Patients Undergoing Open-Heart Surgery on Cardiopulmonary Bypass.

PURPOSE: Red-colored urine often occurs in patients in the perioperative period who undergo cardiac surgery using cardiopulmonary bypass (CPB). This urine color change has been utilized for approximating hemolysis during CPB without a proven relationship for ongoing hemolysis. This case series study aimed to examine the relationship between plasma free hemoglobin (Hb) levels and quantified measures of urine color. METHODS: Ten patients were enrolled in this study. Blood and urine were collected for analyses for the following time points: before surgery, two hours after the initiation of CPB, every 30 min during CPB thereafter, and 0, 2, 4, 12, and 24 hours after the completion of CPB. We measured free Hb in plasma and urine using the azide-methemoglobin method. Photographs of urine were obtained, and the luminance of the three basic colors (red/green/blue) was analyzed by quantitative luminance contrast analysis to find a correlation for hemolysis. RESULTS: Median levels of plasma free Hb were 0.015 (0.010-0.080, n = 10) g/dL at baseline. During the CPB, increases in plasma free Hb levels were measured: median plasma free Hb levels were increased to 0.100 g/dL (0.020-0.240, p = 0.039, vs. baseline, n = 9) at two hours into CPB, median and range, respectively. In contrast, increases in urinary free Hb levels and/or urine color changes were measured only after cessation of CPB in nine patients. CONCLUSION: Urine color change or elevation of urinary free Hb levels followed the elevation of plasma free Hb levels with considerable delay.

Hydration monitoring and rehydration guidance system for athletes based on urine color's L*a*b* parameters.

Maintaining proper hydration is essential for athletes to sustain optimal performance and preserve their physical health. Existing studies have confirmed that urine color is one of the effective indicators for the subjective evaluation of athletes' hydration through the urine color chart. However, the use of urine color charts to evaluate hydration is easily affected by the test environment, urine container and subjective feeling. At present, there are few hydration monitoring instruments based on quantitative analysis of urine color. In recent years, the L*a*b* color model has been widely used in the objective quantitative analysis of color. The L* value represents the luminance change from black to white, the a* value represents the chromaticity change from green to red, and the b* value represents the chromaticity change from blue to yellow. Our previous research has confirmed that the urine color b ∗ value is an effective new indicator to evaluate the hydration of athletes. The research team developed a urine hydration monitoring and rehydration guidance system based on the urine color's L*a*b* parameters via wireless network technology and digital image technology. The hardware structure of the system is composed of a cuvette, a standard light source, a camera, an image collector, a host system, and a touch screen system. The system software is composed of functional modules, such as user information, image acquisition, image processing, and image recognition. The system operation process includes starting the system, filling in basic information, putting the sample, testing the sample, local data review, local data upload, and cloud data review. The system exhibits stable performance, a friendly operation interface, and simple and fast testing. It can objectively and accurately evaluate the hydration of athletes and provide personalized rehydration guidance. The system offers a new method for solving practical problems in sports training, and it has broad application prospects.

Urine color expressed in CIE L*a*b* colorspace during rapid changes in hydration status.

Background: To investigate how rapid changes in hydration affect urine color expressed in CIE L*a*b* colorspace. Methods: This study was a two-day crossover design where subjects (N = 30) came in one visit dehydrated, after a 15 h overnight fluid deprivation, and rapidly rehydrated by drinking at least 1000 mL of water in 2 h. On the other visit subjects reported euhydrated and then rapidly dehydrated 2% by walking (3 mph) in a heat chamber (100°F, 50% humidity) for 2 h. Urine samples on both days were collected pre- and post-dehydration/rehydration. Urine osmolality, urine specific gravity, subjective urine color and objective urine color expressed in CIE L*a*b* colorspace were measured. Results: In the dehydration trial participants experienced a significant weight loss of approximately 2% of their starting, euhydrated body weight. The CIE urine color L*-value significantly decreased (-2.3 units) while the b*-value significantly increased (16 units). Subjective urine color significantly increased (1 unit). Urine osmolality increased (25 mmol/kg) and urine specific gravity increased (0.002 g/mL) between the pre- and post-dehydration conditions, however, neither of these changes were statistically significant. In the rehydration trial participants had a significant 1.5% increase in body weight after the ingestion of water. Significant increases were observed in the CIE urine color L*-value (7 units) and a*-value (1.1 units), while the b*-value significantly decreased (-24 units). Subjective urine color significantly decreased (-3 units). Urine osmolality (-600 mmol/kg) and urine specific gravity (-0.018 g/mL) significantly decreased between the pre- and post-rehydration conditions. Conclusions: Traditional markers of hydration, including urine osmolality and urine specific gravity, did not significantly change in the acute dehydration trial, suggesting that these values may not be responsive to rapid changes in hydration status. However, the CIE L*- and b*-values of urine color significantly decreased in the rapid dehydration trial and significantly increased in the rapid rehydration trial. Thus, the results of the current study suggest that urine color L*- and b*-values expressed in the CIE L*a*b* colorspace were more responsive to changes in hydration status during rapid dehydration than traditional indices of urine concentration and thus may be better markers under such conditions.

[Abnormal urine color assessment: The urine wheel]. / Orientation diagnostique devant une coloration anormale des urines : la roue à urines 2.0.

Looking at the urine for diagnostic purposes, once performed by ancient Egyptians, can still provide some valuable clues in modern medicine. Several diseases have been named after their associated urine color and this underlines the clinical value of visual urine inspection: blue diaper disease, purple urine bag syndrome, black urine disease or porphyria. Abnormal urine color could be challenging for the clinician: it may reveal neoplastic disease (urologic cancer; melanoma), cell lysis (rhabdomyolysis; hemolysis), infection (lymphatic filariasis; malaria), enzyme deficiency (porphyria; alkaptonuria), medication or food intake. In this article, we present the diagnostic approach, the mechanisms involved and the main causes of abnormal urine color.

Efficacy of an Educational Intervention for Improving the Hydration Status of Female Collegiate Indoor-Sport Athletes.

CONTEXT: Research focusing on improving hydration status and knowledge in female indoor-sport athletes is limited. Investigators have demonstrated that hydration education is an optimal tool for improving the hydration status of athletes. OBJECTIVE: To assess the hydration status and fluid intake of collegiate female indoor-sport athletes before and after a 1-time educational intervention. DESIGN: Controlled laboratory study. SETTING: Collegiate women's volleyball and basketball practices. PATIENTS OR OTHER PARTICIPANTS: A total of 25 female collegiate volleyball and basketball athletes (age = 21 ± 1 years, height = 173.5 ± 8.7 cm, weight = 72.1 ± 10.0 kg) were assessed during 6 days of practices. INTERVENTION(S): Participants' hydration status and habits were monitored for 3 practice days before they underwent a hydration educational intervention. Postintervention, participants were observed for 3 more practice days. MAIN OUTCOME MEASURE(S): Change in body mass, fluid consumed, urine specific gravity (Usg), urine color (Ucol), and sweat rate were recorded for 6 practice days. Participants completed a hydration-knowledge questionnaire before and after the intervention. RESULTS: Three-day mean Usg and Ucol were considered euhydrated prepractice (Usg = 1.015 ± 0.006, Ucol = 4 ± 1) and remained euhydrated postpractice (Usg = 1.019 ± 0.005, Ucol = 5 ± 2) during the preintervention period. Decreased prepractice Ucol (P < .01) and increased hydration knowledge (P < .01) were present postintervention. Basketball athletes had greater body mass losses from prepractice to postpractice than did volleyball athletes (P < .001). Overall increases were evident when we compared prepractice and postpractice measures of Usg and Ucol in the preintervention (P < .001 and P = .001, respectively) and postintervention (P = .001 and P < .001) period, respectively. No correlation was found between hydration knowledge and physiological indices of hydration and fluid intake. CONCLUSIONS: Overall, female collegiate indoor-sport athletes were hydrated and knowledgeable on hydration. However, our variable findings indicated that further research on these athletes is needed; clinically, attention should be given to the individual needs of each athlete. More examination will demonstrate whether a 1-time educational intervention may be an effective tool for improving hydration status in this population.

Analysis of the Distribution of Urine Color and Its Relationship With Urine Dry Chemical Parameters Among College Students in Beijing, China - A Cross-Sectional Study.

Objectives: The objective of this study was to provide a new classification method by analyzing the relationship between urine color (Ucol) distribution and urine dry chemical parameters based on image digital processing. Furthermore, this study aimed to assess the reliability of Ucol to evaluate the states of body hydration and health. Methods: A cross-sectional study among 525 college students, aged 17-23 years old, of which 59 were men and 466 were women, was conducted. Urine samples were obtained during physical examinations and 524 of them were considered valid, including 87 normal samples and 437 abnormal dry chemistry parameters samples. The urinalysis included both micro- and macro-levels, in which the CIE L*a*b* values and routine urine chemical examination were performed through digital imaging colorimetry and a urine chemical analyzer, respectively. Results: The results showed that L* (53.49 vs. 56.69) in the abnormal urine dry chemistry group was lower than the normal group, while b* (37.39 vs. 33.80) was greater. Urine color can be initially classified based on shade by grouping b*. Abnormal urine dry chemical parameter samples were distributed more in the dark-colored group. Urine dry chemical parameters were closely related to Ucol. Urine specific gravity (USG), protein, urobilinogen, bilirubin, occult blood, ketone body, pH, and the number of abnormal dry chemical parameters were all correlated with Ucol CIE L*a*b*; according to a stepwise regression analysis, it was determined that more than 50% of the variation in the three-color space values came from the urine dry chemical parameters, and the b* value was most affected by USG (standardized coefficient ß = 0.734, p < 0.05). Based on a receiver operating characteristic curve (ROC) analysis, Ucol ≥ 4 provided moderate sensitivity and good specificity (AUC = 0.892) for the detection of USG ≥ 1.020. Conclusions: Our findings on the Ucol analysis showed that grouping Ucol based on b* value is an objective, simple, and practical method. At the same time, the results suggested that digital imaging colorimetry for Ucol quantification is a potential method for evaluating body hydration and, potentially, health.

Diagnostic accuracy of urinary indices to detect mild dehydration in young men following acute riboflavin, Vitamin C or beetroot supplementation.

BACKGROUND: Individuals of all ages are encouraged to monitor their hydration status daily to prevent clinically severe fluid imbalances such as hyponatremia or dehydration. However, acute oral nutritional supplementation may alter urinary hydration assessments and potentially increase the likelihood of inappropriate clinical decisions or diagnosis. This investigation sought to examine the influence of three common over-the-counter nutritional supplements (beetroot, riboflavin, and Vitamin C) on urinary hydration assessments in physically active young men after a 2% exercise-induced dehydration. DESIGN: Eight males (Mean ± SD; age: 22 ± 3 yr; body mass index: 27 ± 5.0) consumed either a standard meal with supplementation (intervention) or a standard meal without supplementation (control). Participants performed a variety of aerobic or resistance exercises until reaching ≥2% body mass loss in a counter-balanced, double-blinded design. Following exercise participation, urine samples were collected for an 8 h observational period during which food consumption was replicated. Urine samples were analyzed for urine color, specific gravity, volume, and osmolality. Maintenance of ~2% body mass loss (2.6 ± 0.5%; range: 1.7-4.0%) was confirmed following the 8 h observational period. RESULTS: Statistically significant (p < 0.05) changes were noted in urine color following Vitamin C supplementation compared to control; however, the difference was not clinically meaningful. CONCLUSIONS: These findings indicate that urine color, specific gravity, and osmolality maintain clinical utility to detect moderate levels of dehydration in physically active men consuming commercially available doses of beetroot, riboflavin, or Vitamin C.

Development of integrated neonatal cholestasis card for early recognition and referral of neonatal cholestasis.

INTRODUCTION AND AIM: Delayed referral of neonatal cholestasis (NC) can result in significant morbidity and mortality. In this multi-center study, we aimed to evaluate the reliability of the stool card in the Indian population and develop an integrated NC card with (a) urine color identification and (b) stool color for early referral. METHODS: Consecutive children with NC were enrolled and divided into two groups (biliary atresia [BA] and non-BA). Normal healthy children at 6-8 weeks of age served as controls. Each photograph of stool and urine samples of every child was evaluated by 6 parents, 6 paramedical staff, and 4 trainee doctors using a stool color card as a reference for stool samples. RESULTS: Of 319 children (BA [n = 58], non-BA [n = 62], and controls [n = 199]), parents correctly detected dark yellow urine in all NC. Stool samples of 50 (86%) children with BA were unanimously labeled as pale by all observers. The average inter-item correlation showed good correlation between parents and trainee doctors of 0.77 and 0.64 with paramedical staff. CONCLUSION: The integrated NC card proposes to recognize neonatal cholestasis at an early stage irrespective of etiology. It is a major step towards public health benefit both at the community as well as physicians' levels to enable early detection and timely referral and management.

The Effect of Hydration on Urine Color Objectively Evaluated in CIE L*a*b* Color Space.

Urine color has been shown to be a viable marker of hydration status in healthy adults. Traditionally, urine color has been measured using a subjective color scale. In recent years, tristimulus colorimetry developed by the International Commission on Illumination (CIE L*a*b*) has been widely adopted as the reference method for color analysis. In the L*a*b* color space, L* indicates lightness ranging from 100 (white) to 0 (black), while a* and b* indicate chromaticity. a* and b* are color directions: -a* is the green axis, +a* is the red axis, -b* is the blue axis, and +b* is the yellow axis. The L*a*b* color space model is only accurately represented in three-dimensional space. Considering the above, the purpose of the current study was to evaluate urine color during different hydration states, with the results expressed in CIE L*a*b* color space. The study included 28 healthy participants (22 males and 6 females) ranging between the age of 20 and 67 years (28.6 ± 11.3 years). One hundred and fifty-one urine samples were collected from the subjects in various stages of hydration, including morning samples after 7-15 h of water deprivation. Osmolality and CIE L*a*b* parameters were measured in each sample. As the urine osmolality increased, a significant linear increase in b* values was observed as the samples became more pronouncedly yellow (τb = 0.708). An increase in dehydration resulted in darker and significantly more yellow urine, as L* values decreased in lightness and b* values increased along the blue-yellow axis. However, as dehydration increased, a notable polynomial trend in color along the green-red axis was observed as a* values initially decreased, indicating a green hue in slightly dehydrated urine, and then increased as urine became more concentrated and thus more dehydrated. It was determined that 74% of the variance seen in urine osmolality was due to CIE L*a*b* variables. This newfound knowledge about urine color change along with the presented regression model for predicting urine osmolality provides a more detailed and objective perspective on the effect of hydration on urine color, which to our knowledge has not been previously researched.

Risk of Kidney Injury among Construction Workers Exposed to Heat Stress: A Longitudinal Study from Saudi Arabia.

Saudi Arabia (SA) is one of the hottest countries in the world. This study was conducted to assess the impact of summer heat stress in Southeastern SA on short-term kidney injury (KI) among building construction workers and to identify relevant risk factors. Measurements of urinary albumin-creatinine ratio (ACR), height, weight, hydration, symptoms, daily work and behavioral factors were collected in June and September of 2016 from a cohort of construction workers (n = 65) in Al-Ahsa Province, SA. KI was defined as ACR ≥30 mg/g. Multivariate linear regression analysis was used to assess factors related to cross-summer changes in ACR. A significant increase in ACR occurred among most workers over the study period; incidence of KI was 18%. Risk factors associated with an increased ACR included dehydration, short sleep, and obesity. The findings suggest that exposure to summer heat may lead to the development of KI among construction workers in this region. Adequate hydration and promotion of healthy habits among workers may help reduce the risk of KI. A reduction in work hours may be the most effective intervention because this action can reduce heat exposure and improve sleep quality.

Clinical utility of urine specific gravity, electrical conductivity, and color as on-farm methods for evaluating urine concentration in dairy cattle.

BACKGROUND: Urine concentration (UC) provides clinically useful information concerning hydration status and renal function of animals. OBJECTIVES: To characterize the clinical performance of urine specific gravity measured by optical refractometry (USG-R ) or Multistix-SG urine reagent dipstick (USG-D ), urine electrical conductivity using an OAKTON Con 6 conductivity handheld meter (UEC ), urine color (UColor ) using a custom-designed 8-point color chart, and urine creatinine concentration (UCreat ) for assessing UC in dairy cattle. ANIMALS: 20 periparturient Holstein-Friesian cows. METHODS: Urine was obtained by perineal stimulation or urethral catheterization and urine osmolality (UOsm , reference method), USG-R , USG-D , UEC , UColor , and UCreat determined. Diagnostic test performance was evaluated using Spearman's rho and logistic regression to determine the area under the receiver operating curve (AUC) and optimal cut point for diagnosing hypohydration (UOsm ≥800 mOsm/kg). P < .05 was considered significant. RESULTS: The best performing test for diagnosing hypohydration was USG-R (AUC = 0.90) at an optimal cut point ≥1.030. The second-best performing test was UEC (AUC = 0.82) at a cut point of ≥23.7 mS/cm, followed by UCreat (AUC = 0.76) at a cut point of ≥95.3 mg/dL, and UColor (AUC = 0.74) at a cut point of ≥4 on an 8-point scale. Urine specific gravity measured by dipstick performed poorly (AUC = 0.63). CONCLUSIONS AND CLINICAL IMPORTANCE: USG-R and UEC provide practical and sufficiently accurate methods for measuring UC in dairy cattle. Urine color had moderate clinical utility as a no-cost cow-side method for assessing UC, whereas dipstick refractometry is not recommended for assessing UC.