Urine Reagent Strips Are Inaccurate for Assessing Hypohydration: A Brief Report

To assess the diagnostic ability of urine reagent strips to identify hypohydration based on urine specific gravity (USG).

This study examined the agreement of USG between strips and refractometry with Bland-Altman, whereas the diagnostic ability of the strips to assess hypohydration was performed by receiver operating characteristic analysis.

Arkansas high school football preseason practice.

Four hundred fourteen fresh urine samples were analyzed.

Urine specific gravity was assessed by both reagent strips and refractometry. Cutoffs of >1.020 and >1.025 were used for identifying hypohydration.

Bland-Altman analysis showed agreement of the 2 methods. Overall diagnostic ability of the urine strip to identify hypohydration was fair (area under the curve 72%-78%). However, the sensitivity to correctly identify hypohydration was poor (63%-71%), and the specificity of correctly identifying euhydration was poor to fair (68%-83%).

The urine strip method is not valid for assessing hypohydration.