The MRO contacts you when the laboratory reports your specimen as positive, adulterated, substituted, or invalid. This verification interview is your chance to give a legitimate medical explanation, such as a valid prescription, before the MRO decides the final result (49 CFR 40.131).

• Be ready to give the prescriber's name and the medication details. The MRO may ask for records.
• If you do not contact the MRO after being asked to, the MRO may verify the result without talking to you.
• The employer's DER may be asked to tell you to contact the MRO; the DER is not told the reason.