Abstract

has released position statements regarding hydration in athletes and the risks associated with dehydration.1 Dehydration and heat related injuries may result in loss of playing time, decrease in performance, decrease in overall health, and death.2 Because dehydra-tion is one of the primary signs of exertional heat illness,1 health professionals treating high-risk populations should measure hydra-tion status as a preven-tive procedure. Urine specific grav-ity (Usg), change in body mass (BM), urine color (Ucol), urine osmolal-ity (Uosm), and plasma osmolality (Posm) are common measures of hydration status, and each method presents advantages and limi-tations. Some measures of hydration status are more appropriate for a laboratory set-ting, whereas others are more appropriate for clinical measurement. Tools that provide greatest measurement accuracy and reli-ability are preferred for research,3 but tools that require little technical expertise and low expense are customarily utilized in a clini-cal setting. Researchers disagree about the technical standard for measuring hydration status in the clinical setting. Several groups of researchers have evaluated hydration indi-ces to determine the most reliable and valid clinical measurement of hydration status. The purpose of this report is to review the current evidence about the best clinical hydration measurement technique.