Accuracy of Urine Specific Gravity and Osmolality as Indicators of Hydration Status

2005 ◽  
Vol 15 (3) ◽  
pp. 236-251 ◽  
Author(s):  
Robert A. Oppliger ◽  
Scott A. Magnes ◽  
LeRoy A. Popowski ◽  
Carl V. Gisolfi
Keyword(s):  
Body Weight ◽  
Specific Gravity ◽  
Decision Model ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Medical Decision ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Accurate Assessment ◽  
Factors Affecting

To reduce the adverse consequences of exertion-related and acute intentional dehydration research has focused on monitoring hydration status. This investigation: 1) compared sensitivity of urine specific gravity (Usg), urine osmolality (Uosm) and a criterion measurement of hydration, plasma osmolality (Posm), at progressive stages of acute hypertonic dehydration and 2) using a medical decision model, determined whether Usg or Uosm accurately reflected hydra-tion status compared to Posm among 51 subjects tested throughout the day. Incremental changes in Posm were observed as subjects dehydrated by 5% of body weight and rehydrated while Usg and Uosm showed delayed dehydration-related changes. Using the medical decision model, sensitivity and specificity were not significant at selected cut-offs for Usg and Uosm. At the most accurate cut-off values, 1.015 and 1.020 for Usg and 700 mosm/kg and 800 mosm/kg for Uosm, only 65% of the athletes were correctly classified using Usg and 63% using Uosm. Posm, Usg, and Uosm appear sensitive to incremental changes in acute hypertonic dehydration, however, the misclassified outcomes for Usg and Uosm raise concerns. Research focused on elucidating the factors affecting accurate assessment of hydration status appears warranted.

scholarly journals Urine specific gravity as a diagnostic tool for dehydration in children

2010 ◽  
Vol 50 (5) ◽  
pp. 269 ◽  
Author(s):  
Kalis Joko Purwanto ◽  
Mohammad Juffrie ◽  
Djauhar Ismail
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Specific Gravity ◽  
Diagnostic Tool ◽  
Clinical Judgment ◽  
Plasma Osmolality ◽  
Body Weight Loss ◽  
Urine Osmolality ◽  
Urine Specific Gravity ◽  
Urine Production

Background Using clinical judgment to diagnose dehydration can be highly subjective. To diagnose dehydration, it would be ideal to have an accurate, inexpensive, objective and easy-to-perform diagnostic tool. In cases of dehydration, plasma osmolality rises, causing an increase in antidiuretic hormone (ADH) secretion. The increased ADH reduces urine production and increases urine osmolality. Previous studies have show that urine osmolality correlates well to urine specific gravity. We investigated if urine specific gravity can be a reliable and objective detennination of dehydration status.Objective To assess the accuracy of using urine specific gravity as a diagnostic tool to determine dehydration status of children with diarrhea.Methods We conducted the study in the pediatric ward of Sardjito Hospital from September 2009 to December 2009. Using a refractometer we measured urine specific gravity from patients with diarrhea. This measurement was then compared to a standard of acute body weight loss, with dehydration defined as weight loss of 5% or more. The cut-off value for defining dehydration using specific gravity measurements was detennined by a receiver-operator curve (ROC).Results Out of 61 pediatric patients who were recruited in this study, 18 (30%) had dehydration as defined by a body weight loss of 5% or more. Based on the ROC, we determined the cut off  value for urine specific gravity to be 1.022. Using this value, urine specific gravity was 72% sensitive (95% CI 52 to 93), and 84% specific (95% CI 73 to 95) in determining dehydration status.Conclusion Urine specific gravity is less accurate than clinical judgment in determining dehydration status in children with diarrhea.

Hydration status of Greco-Roman wrestlers in an authentic precompetition situation

2013 ◽  
Vol 38 (6) ◽  
pp. 621-625 ◽  
Author(s):  
Vahur Ööpik ◽  
Saima Timpmann ◽  
Andres Burk ◽  
Innar Hannus
Keyword(s):  
Specific Gravity ◽  
Body Mass ◽  
Urine Osmolality ◽  
Mass Gain ◽  
The Body ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Greco Roman ◽  
Reduced Body ◽  
Body Mass Gain

We assessed the urinary indexes of hydration status of Greco-Roman wrestlers in an authentic precompetition situation at the time of official weigh-in (OWI). A total of 51 of 89 wrestlers competing in the Estonian Championship in 2009 donated a urine sample. Questionnaire responses revealed that 27 wrestlers (body mass losers (BMLs)) reduced body mass before the competition, whereas 24 wrestlers (those who do not lose body mass (n-BMLs)) did not. In 42 wrestlers, values of urine specific gravity ≥1.020 and urine osmolality ≥700 mOsmol·kg−1 revealed a hypohydrated status. The prevalence of hypohydration in the BMLs (96%) was higher than in the n-BMLs (67%) (χ2 = 7.68; p < 0.05). The prevalence of serious hypohydration (urine specific gravity >1.030) was 5.3 times greater (χ2 = 8.32; p < 0.05) in the BMLs than in the n-BMLs. In the BMLs, the extent of body mass gain during the 16-h recovery (2.5 ± 1.2 kg) was associated (r = 0.764; p < 0.05) with self-reported precompetition body mass loss (4.3 ± 2.0 kg) and exceeded the body mass gain observed in the n-BMLs (0.7 ± 1.2 kg; p < 0.05). We conclude that hypohydration is prevalent among Greco-Roman wrestlers at the time of OWI. The prevalence of hypohydration and serious hypohydration is especially high among wrestlers who are accustomed to reducing body mass before competition. These results suggest that an effective rehydration strategy is needed for Olympic-style wrestlers, and that changes in wrestling rules should be considered to reduce the prevalence of harmful body mass management behaviours.

scholarly journals Assessment of hydration status in a large population

2014 ◽  
Vol 113 (1) ◽  
pp. 147-158 ◽  
Author(s):  
Stephanie Baron ◽  
Marie Courbebaisse ◽  
Eve M. Lepicard ◽  
Gerard Friedlander
Keyword(s):  
Large Population ◽  
Plasma Osmolality ◽  
High Specificity ◽  
Urine Osmolality ◽  
The Elderly ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Technical Expertise ◽  
Urinary Markers ◽  
Large Sample

Both acute and chronic dehydration can have important implications for human behaviour and health. Young children, non-autonomous individuals and the elderly are at a greater risk of dehydration. Mild hypertonic dehydration could be related to less efficient cognitive and physical performance and has been reported to be associated with frequently occurring pathological conditions, especially nephrolithiasis. The assessment of hydration status in a large sample appears to be of interest for conducting epidemiological and large clinical studies aimed at improving preventive and curative care. Especially in large-population studies, methods that are used have to be accurate, cheap, quick and require no technical expertise. Body weight change is widely used to determine acute hydration changes, but seems to be insufficiently accurate in longitudinal studies. Bioimpedance analysis methods enable the assessment of total body water content, but their use is still under debate. Because plasma osmolality directly reflects intracellular osmolality, it constitutes a good marker to assess acute hydration changes, but not chronic hydration status because it changes constantly. Moreover, venepuncture is considered to be invasive and is not suitable for a large-sample study, especially in children. Urinary markers appear to be good alternatives for assessing hydration status in large populations. Collection of urine samples is non-invasive and cheap. High technical expertise is not required to perform urinary marker measurements and these measurements can be carried out quickly. Thus, methods based on urinary markers are very well suited for field studies. Urine colour is probably the least sensitive marker despite its high specificity. Urine osmolality and especially urine specific gravity could be easily used for determining hydration status in large-sample studies.

scholarly journals Influence of progressive fluid restriction on mood and physiological markers of dehydration in women

2012 ◽  
Vol 109 (2) ◽  
pp. 313-321 ◽  
Author(s):  
Nathalie Pross ◽  
Agnès Demazières ◽  
Nicolas Girard ◽  
Romain Barnouin ◽  
Francine Santoro ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Water Intake ◽  
Vital Signs ◽  
Plasma Osmolality ◽  
Physiological Parameters ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Fluid Restriction ◽  
Experimental Conditions ◽  
Physiological Markers

The present study evaluated, using a well-controlled dehydration protocol, the effects of 24 h fluid deprivation (FD) on selected mood and physiological parameters. In the present cross-over study, twenty healthy women (age 25 (se 0·78) years) participated in two randomised sessions: FD-induced dehydration v. a fully hydrated control condition. In the FD period, the last water intake was between 18.00 and 19.00 hours and no beverages were allowed until 18.00 hours on the next day (23–24 h). Water intake was only permitted at fixed periods during the control condition. Physiological parameters in the urine, blood and saliva (osmolality) as well as mood and sensations (headache and thirst) were compared across the experimental conditions. Safety was monitored throughout the study. The FD protocol was effective as indicated by a significant reduction in urine output. No clinical abnormalities of biological parameters or vital signs were observed, although heart rate was increased by FD. Increased urine specific gravity, darker urine colour and increased thirst were early markers of dehydration. Interestingly, dehydration also induced a significant increase in saliva osmolality at the end of the 24 h FD period but plasma osmolality remained unchanged. The significant effects of FD on mood included decreased alertness and increased sleepiness, fatigue and confusion. The most consistent effects of mild dehydration on mood are on sleep/wake parameters. Urine specific gravity appears to be the best physiological measure of hydration status in subjects with a normal level of activity; saliva osmolality is another reliable and non-invasive method for assessing hydration status.

scholarly journals Validity of Urine Specific Gravity When Compared With Plasma Osmolality as a Measure of Hydration Status in Male and Female NCAA Collegiate Athletes

2016 ◽  
Vol 30 (8) ◽  
pp. 2219-2225 ◽  
Author(s):  
Lesley M. Sommerfield ◽  
Steven R. McAnulty ◽  
Jeffrey M. McBride ◽  
Jennifer J. Zwetsloot ◽  
Melanie D. Austin ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Plasma Osmolality ◽  
Collegiate Athletes ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Male And Female

Hydration Status, Knowledge, and Behavior in Youths at Summer Sports Camps

2008 ◽  
Vol 3 (3) ◽  
pp. 262-278 ◽  
Author(s):  
Nora R. Decher ◽  
Douglas J. Casa ◽  
Susan W. Yeargin ◽  
Matthew S. Ganio ◽  
Michelle L. Levreault ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Urine Osmolality ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Self Assessment ◽  
And Behavior ◽  
Summer Sports Camp

Purpose:To assess the hydration status and level of hydration knowledge of youths at summer sports camps.Methods:Sixty-seven active youths, 57 males (mean ± SD, 12 ± 2 y, 136 ± 16 cm, 50.6 ± 21.1 kg) and 10 females (13 ± 2 y, 153 ± 8 cm, 45.2 ± 9.0 kg) participated in 4 d of sports camp. Hydration status was assessed before the first practice (AM) and after the second practice (PM). Participants completed suriveys assessing hydration knowledge (HAQ) and hydration habits on day 3 and a self-assessment (EQ#1).Results:Mean AM urine specific gravity (USG) and urine osmolality (Uosm) scores ranged from minimal to significant dehydration across 4 d, even when temperatures were mild. Correlations between hydration indices and EQ#1, ranging from 0.11 to −0.51, were statistically significant (P < .05), indicating that subjects recognized when they were doing a good or bad job hydrating. HAQ did not correlate strongly with hydration indices suggesting other impediments to hydration. Thirst correlated negatively with EQ#1 (from −0.29 to −0.60).Conclusion:Hydration at summer sports camp is a concern and special efforts need to be made to help youths develop hydration strategies.

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

2021 ◽  
pp. 194173812110384
Author(s):  
Yasuki Sekiguchi ◽  
Courteney L. Benjamin ◽  
Cody R. Butler ◽  
Margaret C. Morrissey ◽  
Erica M. Filep ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Mass Loss ◽  
Body Mass ◽  
Urine Osmolality ◽  
Urine Specific Gravity ◽  
Venn Diagram ◽  
Hydration Status ◽  
Body Mass Loss ◽  
Living Situation ◽  
Urine Color

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 least 2 WUT markers resulted in sensitivities of 0.652 (2 WUT criteria met) and 0.933 (3 WUT criteria met) to detect urine osmolality >700 mOsmol. Conclusion: These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality were greater than euhydration cutoff points. 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.

Urinary Indices of Hydration Status

1994 ◽  
Vol 4 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Carl M. Maresh ◽  
John W. Castellani ◽  
Michael F. Bergeron ◽  
Robert W. Kenefick ◽  
...  
Keyword(s):  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Field Studies ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Plasma Sodium ◽  
Strongly Correlated ◽  
Laboratory Studies ◽  
Urine Color ◽  
Precision And Accuracy

Athletes and researchers could benefit from a simple and universally accepted technique to determine whether humans are well-hydrated, euhydrated, or hypohydrated. Two laboratory studies (A, B) and one field study (C) were conducted to determine if urine color () indicates hydration status accurately and to clarify the interchangeability of , urine osmolality (), and urine specific gravity () in research. , , and were not significantly correlated with plasma osmolality, plasma sodium, or hemato-crit. This suggested that these hematologic measurements are not as sensitive to mild hypohydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, was strongly correlated with and U„sm. It was concluded that (a) may be used in athletic/industrial settings or field studies, where close estimates of or are acceptable, but should not be utilized in laboratories where greater precision and accuracy are required, and (b) and may be used interchangeably to determine hydration status.

scholarly journals Progressive Dehydration in Junior Laser Class Sailors During World Championship

2018 ◽  
Vol 28 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Giannis Arnaoutis ◽  
Panagiotis Verginadis ◽  
Adam D. Seal ◽  
Ioannis Vogiatzis ◽  
Labros S. Sidossis ◽  
...  
Keyword(s):  
Body Weight ◽  
Specific Gravity ◽  
Environmental Temperature ◽  
Urine Concentration ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Training Experience ◽  
World Championship ◽  
Body Weights ◽  
Before And After

The purpose of this article is to assess the hydration status of elite young sailing athletes during World Championship competition. Twelve young, elite, male, Laser Class sailors (age: 15.8 ± 1.1 y, height: 1.74 ± 0.1 m, weight: 65.1 ± 1.5 kg, body fat: 12.5 ± 3.1%, training experience: 7.0 ± 1.2 y) participated in this descriptive study. After three-day baseline bodyweight measurements, hydration status was assessed via pre- and post-race body weights, urine-specific gravity, and thirst ratings via a visual analog scale during four consecutive days of racing. Measurements and data collection took place at the same time each racing day, with mean environmental temperature, humidity, and wind speed at 23.0 ± 0.8°C, 64–70%, and 9 ± 1 knots, respectively. Average racing time was 130 ± 9 min. Body weight was significantly decreased following each race-day as compared to prerace values (Day 1: −1.1 ± 0.2, Day 2: −2.5 ± 0.1, Day 3: −2.8 ± 0.1, and Day 4: −3.0 ± 0.1% of body weight; p < 0.05). The participants exhibited dehydration of −2.9 ± 0.2 and −5.8 ± 0.2% of body weight before and after the fourth racing day as compared to the three-day baseline body weight. Urine-specific gravity (pre–post → Day 1: 1.014–1.017; Day 2: 1.019–1.024; Day 3: 1.021–1.026; Day 4: 1.022–1.027) and thirst (pre–post → Day 1: 2.0–5.2; Day 2: 3.2–5.5; Day 3: 3.7–5.7; Day 4: 3.8–6.8) were also progressively and significantly elevated throughout the four days of competition. The data revealed progressive dehydration throughout four consecutive days of racing as indicated by decreased body weight, elevated urine concentration, and high thirst.

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