(26) EXAMINING THE WUT (BODY WEIGHT, URINE COLOR, AND THIRST PERCEPTION) VENN DIAGRAM COMPARED TO 24-HR HYDRATION

Purpose: To examine the validity and explore potential sex differences in the accuracy of the WUT Venn diagram for hydration status determination. A secondary aim of the study was to examine the accuracy of self-assessed WUT scores, and lab based WUT scores for hydration. Methods: Eight males (age: 22.3 ± 4.2 years, body weight: 81.9 ± 15.3 kg) and ten females (age: 26.4 ± 7 years, body weights: 74.8 ± 16.3 kg) completed the study. Participants collected first morning, afternoon, and 24-hour urine three out of seven consecutive days. Body mass, urine color, urine osmolality (U_osm), and thirst perception were measured or recorded for first morning and afternoon samples in free living conditions. Urine color and U_osm were assessed for 24-hr samples. The number of markers indicating dehydration was categorized into 0, 1, 2, or 3 WUT scores. Receiver-operating characteristics analysis calculated the sensitivity and specificity of 0,1,2 or 3 WUT markers in detecting dehydration or euhydration. The 24-hr U_osm cutoff for euhydration was < 500 mOsm/L. Significance was set a priori at p< .05. Results: Females (4 ± 1) self-reported urine color significantly lower than males (5 ± 1; p=.040). Females (471.5 ± 51.7mOsm/L) tended to have a decreased 24-hr osmolality compared to males (622.1 ± 57.8mOsm/L; p=.070). There were no sex differences (p=.169), or significant time point differences for U_osm for spot urine (p >.184). The first morning (p< .001) and afternoon (p=.032) WUT scores were significantly greater when self-rated compared to lab-rated WUT scores. Morning (r=.571; p< .001) and afternoon (r=.715; p< .001) WUT scores were significantly correlated between lab and self-ratings. Afternoon (r=.568; p< .001) WUT scores were significantly correlated with 24-hr U_osm values, but first morning measures were not (r=.059; p=.673). Overall, sensitivity (Sn: .37-.67), specificity (Sp: 0-.85) and LR+ (LR+: .667 - 2.60) ranges demonstrated limited ability to predict 24-hr U_osm. Conclusions: More research is necessary to determine differences between lab-based and self-assessed WUT hydration as well as the clinical validity and reliability of the WUT Venn diagram to self-identify hydration status. Practical Applications: In field settings (athletics, occupational, and military operations), the utility of the WUT Venn diagram should be used with caution if used to reflect overall hydration status. Acknowledgements: None