Negative Dilute

Definition - What does Negative Dilute mean?

Negative dilute refers to a urine specimen featuring a disproportionate amount of creatinine, a biochemical agent in the blood, and specific gravity parameters outside the range of baseline metrics, raising questions over the legitimacy of the specimen. On the surface, a negative dilute implicates an applicant or current employee of tampering with a specimen; however, it can also be the result of health issues where fluid intake might exceed the norm.

WorkplaceTesting explains Negative Dilute

Although many applicants and employees may attempt to manipulate a urine specimen, contrary to popular belief, excessive consumption of fluids does not evacuate drug metabolites from the system. A drug testing policy sets the criteria for retesting applicants and employees with a second negative dilute result. And, the policy should make clear the consequences for hiring or dismissal reserved at the employer’s discretion. Both Department of Transportation (DOT) and non-DOT employers have an obligation under the federal mandate 49 CFR Part 40.197 to authorize retesting in line with an existing policy demonstrating universal fairness for all employees, a one-time collection clause, and acceptance of second test result as a negative dilute.

Strict guidelines apply where creatinine levels exceed or are equal to 2 mg/dl but less than 5 mg/dl, combined with anomalous specific gravity variables, warrant retesting from the donor under direct supervision by a medical review officer (MRO). Moreover, specimens with a creatinine concentration of 5 mg/dl or greater but less than 20 mg/dl combined with anomalous specific gravity variables are designated as a negative dilute, leaving the outcome to the employer. For DOT applicants and employees, a second specimen with a negative dilute test result can be grounds for disqualification or termination given the aspects related to safety-sensitive positions.

Because drug metabolites may not appear in initial drug testing, a comprehensive drug testing policy that requires retesting that correlate with original findings can help deter false negatives. However, applicants and employees can exercise their right to deny retesting, incurring a positive confirmation where rejection of employment or termination of employee status may be the outcome.

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