How Does a Laboratory Identify a Substituted or Adulterated Urine Specimen?

A laboratory identifies a substituted or adulterated DOT urine specimen from validity test results that meet set criteria on separate portions of the specimen. Under 49 CFR 40.88(b), a specimen is substituted when the creatinine concentration is less than 2 mg/dL and the specific gravity is less than or equal to 1.0010 or greater than or equal to 1.0200. These values must be found on both the initial and confirmatory creatinine tests and on both the initial and confirmatory specific gravity tests, on two separate aliquots.

Under 49 CFR 40.89, the laboratory uses the adulterant cutoff concentrations in the HHS Mandatory Guidelines, with one aliquot for the initial test and a separate aliquot for the confirmation test. It reports results at or above the cutoffs as adulterated, or for pH, results at or above or below the set values, and provides the numerical value that supports the result.

Under 49 CFR 40.97(b)(2), an adulterated result is reported with the adulterant noted, confirmatory test values when applicable and remarks. A substituted result is reported with confirmatory test values for creatinine and specific gravity. Under 40.97(f)(2), the laboratory provides these numerical values to the MRO without a request.

For comparison, under 40.88(a), a specimen is dilute, not substituted, when creatinine is at least 2 mg/dL but less than 20 mg/dL and specific gravity is greater than 1.0010 but less than 1.0030 on a single aliquot. The MRO's review of these results is covered in How Does an MRO Review an Adulterated or Substituted DOT Drug Test?.

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