URINARY INDEXES OF HYDRATION STATUS

Athletes and researchers could benefit from a simple and universally a ccepted technique to determine whether humans are well-hydrated, euhyd rated, or hypohydrated. Two laboratory studies (A, B) and one field st udy (C) were conducted to determine if urine color (U(col)) indicates hydration status accurately and to clarify the interchangeability of U (col), urine osmolality (U(osm)), and urine specific gravity (U(sg)) i n research. U(col), U(osm), and U(sg) were not significantly correlate d with plasma osmolality, plasma sodium, or hematocrit. This suggested that these hematologic measurements are not as sensitive to mild hypo hydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, U(col) was strongly correlated w ith U(sg) and U(osm). It was concluded that (a) U(col) may be used in athletic/industrial settings or field studies, where close estimates o f U(sg) or U(osm) are acceptable, but should not be utilized in labora tories where greater precision and accuracy are required, and (b) U(os m) and U(sg) may be used interchangeably to determine hydration status .