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 β = 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.

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.

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.

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 (τ_b = 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.

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.

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.

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.

Hydration Status and Fluid Needs of Division I Female Collegiate Athletes Exercising Indoors and Outdoors

The purpose was to determine differences in acute and chronic hydration status in female student-athletes (n = 40) practicing in moderate, dry conditions (17-25 °C, 30-57% humidity) indoors and outdoors. Body weight and urine samples were recorded before and after exercise as well as fluid intake. Sweat rates expressed as median and interquartile range did not differ, but fluid intake was significantly higher during indoor (0.64 [0.50, 0.83] L/h) vs. outdoor conditions (0.51 [0.43, 0.63] L/h), p = 0.001. Fluid intake compensated for indoor sweat rate but not outdoors. When exercising indoors, 49% of the student-athletes reported urine specific gravity (USG) values >1.020, and 24% of the day after morning samples were scored ≥4 on the color chart rating. The percentages increased to 58% and 31%, respectively, when exercising outdoors (p > 0.05). Thus, fluid intake was higher indoors vs. outdoors but sweat rate did not differ among athletes. Yet, chronic hydration status was impaired in more than 50% of the student-athletes with a discrepancy between USG scores and urine color scores identifying underhydration. This suggest that 24-h fluid intake should be taken into account and that hydration protocols may need to be tailored individually based on urine USG values. Practice location (indoors vs. outdoors) may further complicate hydration protocols.

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 (U_SG) 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) U_SG 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) U_SG 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 U_SG 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.

Early prediction of acute kidney injury by clinical features of snakebite patients at the time of hospital admission

Background:

Snakebite is a major health problem in India. Venomous snakebite, which is an important medical hazard in several tropical countries including India, affects thousands of people per year and some of them develop acute kidney injury (AKI).

Aims:

This study was performed to find out 1) early clinical predictors for acute kidney injury in snakebite patients at the time of hospital admission and 2) incidence of acute kidney injury in snakebite patients.

Materials and Methods:

171 consecutively admitted non-diabetic, non-hypertensive snakebite patients were examined. Multivariate linear regression analysis with 95 percent confidence interval (CI) was done for statistical analysis. Analyses were performed by software Statistical Package for the Social Sciences (SPSS) (17^th version for Windows).

Results:

Incidence of acute kidney injury was 43.27%. Development of acute kidney injury was independently associated with 20 min whole blood clotting test (20 min WBCT) (P value = 0.029; CI 95%), dark or brown color urine (P value = 0.000; CI 95%), and time interval between snakebite and anti-snake venom administration (P value = 0.000; CI 95%). Age (P value = 0.011; CI 95%) and presence of neurological signs (P value = 0.000; CI 95%) were negatively correlated with development of acute kidney injury.

Conclusion:

Incidence of acute kidney injury is slightly higher in our study than previous studies. Early prediction of acute kidney injury development in snakebite patients can be done by presence of black or brown urine, 20 min WBCT > 20 min, and increased time interval between snakebite and administration of anti-snake venom at the time of hospital admission. Young age group of snakebite patients develops acute kidney injury more commonly.