Effect of Urine Agitation on Measurements of Hydration Status.

Abstract

Hypohydration can have significant implications on physiological functions of the body and has the potential to decrease level of performance. In addition to performance decrements, hypohydration can also lead to increased thermal and cardiovascular strain. As a preventative measure athletic trainers are commonly required to attain urine specimen samples to assess athlete hydration status for weight checks and monitoring body mass losses. Unfortunately, immediate examination of urine samples is not always possible. As the urine sample sits, sedimentation develops. No current literature addresses the sedimentation of urine samples and what procedures should be performed to ensure an accurate hydration assessment. OBJECTIVE: The purpose of this study is to determine if agitation of urine samples is comparable to the criterion measure, urine osmolality measured within two hours of collection. DESIGN: We used a descriptive diagnostic validity test design to investigate the effects of agitation of urine samples on the measure of hydration status. SETTING: Biochemical Research Laboratory at Indiana State University. PARTICIPANTS: Seventy-five healthy participants (41 males, 34 females; mean age=22±5years; mean self-reported height=172±23cm and mass=77±17kg) recruited from a university campus provided one or more samples (total samples=81). INTERVENTION: The independent variable was agitation type with 3 levels: vortex mixed, hand shaken, and no agitation. Following recruitment, participants completed the informed consent and a short health questionnaire to rule out any exclusion criteria such as kidney disease, diabetes, etc. Participants were provided with a clean specimen cup and were asked to provide a sample. Large samples were encouraged as they were then split evenly into three cups and labeled according to participant number and agitation type. Hand shaken samples were shaken 10 times in an hourglass fashion, from right side up to up side down. Vortex samples were placed on the vortex mixer for 10 seconds. Non-agitation samples were not disturbed. MAIN OUTCOME MEASURES: Urine osmolality, as measured by a freezing point depression osmometer was used to determine hydration status within two hours of specimen collection and again after 48 hours. Agitation was only performed prior to the second measurement of hydration status, after 48 hours had passed. A one-way ANOVA was performed to compare the two methods of agitation against the criterion control. RESULTS: No significant differences were identified (F3,316 = 0.00027, p =0.99, 1-β=1.00) between the no agitation (mean=724±262), hand shaken(mean=723±263) and vortex (mean=724±263) methods when compared to the criterion control(mean=723±262). CONCLUSIONS: The findings of this study demonstrated no differences in hydration status measurements between the two agitation methods and the control. For practitioners who are unable to immediately measure the hydration status of urine samples, agitation of the urine specimen is not necessary in order to obtain a valid measure of hydration status using an osmometer.