The defined HHS/DOT substituted urine criteria validated through a controlled hydration study.

This controlled hydration study was designed to validate the substitution criteria used by the Substance Abuse and Mental Health Services Administration (SAMHSA) to classify a workplace urine specimen as inconsistent with normal human urine. Study participants (n = 56) ingested at least 80 oz (2370 mL) of fluid over a 6-h period, 40 oz during the first 3 h (DOT hydration protocol) and 40 oz during the second 3-h period. Urine specimens (n = 498) were collected upon awakening, just prior to hydration, at the end of each hour of the 6-h test period, and upon awakening the next day. No urine specimen satisfied the paired substitution criteria of urine creatinine < or = 5.0 mg/dL and specific gravity < or = 1.001 or > or = 1.020. Seventy-three percent of the participants produced at least one specimen meeting the criteria for dilute urine: urine creatinine < 20.0 mg/dL and specific gravity < 1.003. Fifty-five percent of the participants produced at least one dilute urine specimen during the first 3 h of hydration. In conclusion, this controlled hydration study supports the criteria set by SAMHSA for classifying a specimen as substituted (inconsistent with normal human urine).