A dilute specimen is a urine specimen whose creatinine and specific gravity are lower than expected for human urine. The laboratory reports it and the MRO passes the result to the employer as dilute negative or dilute positive (49 CFR 40.197).

• Dilute positive: treated as a verified positive result.
• Dilute negative with very low creatinine (as described in 40.197(b)): the MRO directs the employer to conduct an immediate recollection under direct observation.
• Other dilute negative results: the employer may choose to have the employee retested, applying the same policy to all employees in the same category. The retest is not observed unless the rules require it.

When a recollection is needed, create a new test request for the employee and follow the MRO's instructions. The result of the second test is the one that counts.

Order a drug or alcohol test · 49 CFR Part 40, Subpart G