Ensure Accurate Drug Tests with a Medical Review Officer

Michelle Hopkins

The Department of Transportation (DOT) Drug and Alcohol Clearinghouse  that launched January 6, 2020 ushered in increased reporting requirements for medical review officers (MROs) regarding drug test results of employees under DOT regulation. This article is for general informational purposes only, in response to questions from our customers about MROs, what they do, and their training. Concentra does not provide MRO services. When MRO services are needed because a laboratory we work with has verified a non-negative result, we enlist a MRO through our preferred vendor for review of the result. Concentra works exclusively with laboratories certified by SAMHSA (Substance Abuse and Mental Health Services Administration).

False drug results happen. Certain medications are among the agents that can cause false positive results, and tests or specimens being tampered with is a factor common in false negatives, according to research studies.1,2,3,4 Statistically, one study concluded, false positives may occur in as many as 5 to 10 percent of cases and false negatives, in slightly more, about 10 to 15 percent of the time.5 You want accurate drug testing, and this medical professional has an important role in making sure you get it.

Working with a medical review officer

A medical review officer (MRO) is the linchpin in an effective drug testing program and the one touchpoint of all other participants involved in drug testing: the donor, the employer, the collection site, the laboratory and, where applicable, state and federal agencies. In the simplest terms, a MRO receives and reviews non-negative laboratory drug tests and evaluates whether the result has a justifiable medical reason or determines if sample adulteration or substitution has occurred. The medical review officer does this by following a proscribed protocol to ensure chain of custody and employee confidentiality.

Who decides whether to involve a MRO?

If you have employees who perform safety-sensitive functions that are regulated by the Department of Transportation (DOT), the decision to use the services of a medical review officer has already been made for you. DOT regulations, specifically in 49 CFR Part 40.123 Subpart G, outline all requirements pertaining to MROs in regulated drug testing.

For non-regulated drug tests that you undertake under your own company policy and/or in compliance with state laws, you may have a choice whether to use a MRO, depending on what state law says. But, even if not mandated by law, using a MRO is a good practice to ensure accuracy of testing – for your peace of mind and that of your employees – and to reduce the risk of legal liability.

“The use of the medical review officer greatly enhances the validity and reliability of the overall drug testing process. This process helps ensure fairness to the donor and offers more protection to the employer/agency in any case of later litigation due to a ‘positive’ drug test where the donor may have actually had a legitimate medical explanation. It is the job of the MRO to ensure the integrity of the drug test, and without an MRO, there is no assurance of this integrity,” Global HR Research states in a blog post.6

Medical review officer vs. medical examiner

Before turning to a description of a MRO’s roles, responsibilities, and training, employers sometimes wonder if there is a difference between a medical review officer and a medical examiner. The Federal Motor Carrier Safety Administration (FMCSA) describes the difference in this definition:

“A medical review officer is a licensed physician responsible for receiving and reviewing laboratory results generated by an employer’s drug testing program. A medical examiner is a person who is licensed, certified, or registered, in accordance with applicable state laws and regulations, to perform physical examinations, and may include doctors of medicine, doctors of osteopathy, physician assistants, advanced practice nurses, and doctors of chiropractic.”7 So, you see, they are different.

A medical review officer’s qualifications

In addition to being a licensed physician (doctor of medicine or doctor of osteopathy), a MRO is required to:8

  • Have knowledge and clinical experience in substance abuse disorders
  • Have knowledge of pharmacology and toxicology of illicit drugs
  • Have detailed knowledge of legitimate medical explanations for drug test results in the context of all available information, including an accurate health history
  • Be trained in collection procedures; interpretation of results; chain of custody, reporting, and recordkeeping requirements
  • Complete training on any revisions to federal mandatory guidelines, prior to changes becoming effective
  • Pass satisfactorily an initial examination administered by a nationally recognized entity or subspecialty board approved by the Health and Human Services Secretary
  • Complete requalification training at least every five years and pass satisfactorily a requalification examination

How do I find a MRO near me?

You can find a qualified medical review officer by going to the Medical Review Officer Certification Council website.

MRO process and the time required

Regulated drug testing requires the donor to provide a urine specimen, which is split into two vials (split testing). Two testing methods are used. If both are positive, the results are reported to the medical review officer. The laboratory performs specimen validity testing to determine if any adulteration has occurred and stores the samples for at least 12 months.9

A positive drug test result from the laboratory in either regulated or non-regulated drug testing does not necessarily mean the employee (or applicant) has misused drugs. Nor does a laboratory finding of an invalid, substituted, or adulterated drug test automatically mean the individual has tampered with the specimen. A physician with detailed knowledge of all possible legitimate medical explanations – the medical review officer – has the final word.8

A medical review officer will:

  • Review all appropriate documentation
  • Interview the donor to investigate whether there are valid medical explanations for a non-negative test
  • If an initial drug test is negative, the findings are confirmed and the results are sent to the employer
  • If the initial drug test is positive, the MRO will contact the donor to see if they are on any medications or have any other legitimate medical explanation for the positive result (usually within 24 hours). If the donor does not answer, the MRO may leave up to three voicemails.
  • The donor is given 72 hours to respond. If there is no response within that time, the MRO notifies the employer to have the donor contact the MRO. The MRO can only characterize the test as “non-negative” or needing further inquiry to the employer, and cannot say the test is “positive.”

Transit of a sample may take 24 hours. Lab testing may take up to several days if a substance is found in the sample.

MRO’s role in the new FMCSA Drug and Alcohol Clearinghouse

The FMCSA launched its new Drug and Alcohol Clearinghouse in January 2020 as an additional safeguard to prevent people with unresolved drug or alcohol violations from getting behind the wheel of a regulated commercial vehicle. Along with employers, medical review officers have new requirements for reporting information to the Clearinghouse. MROs are required to report:

  • Verified positive, adulterated, or substituted drug test results (within two days of finalizing that determination)
  • Refusal to submit to a drug test requiring a determination by the MRO (also within the two-day window)
  • Changes made to a verified drug test

As outlined in § 40.149, a medical review officer may change a verified drug test only in three situations:

  1. After reopening a verification that was completed without interviewing the employee
  2. If new information becomes available that demonstrates the laboratory made an error in identifying or testing the employee’s primary or split specimen
  3. If the medical review officer, within 60 days of making the original verification, receives information (that could not have been provided at the time) of a legitimate medical explanation; also, if the medical review officer receives credible new or additional information that a legitimate medical explanation exists for an adulterated or substituted result

Which drugs will elicit a positive verification by the MRO?

A medical review officer must verify a confirmed positive test for marijuana, cocaine, amphetamines, semi-synthetic opioids (i.e., hydrocodone, hydromorphone, oxycodone, and oxymorphone), and/or PCP unless the employee can present a legitimate medical explanation.10 The employee must be given an opportunity to offer an explanation and the burden of proof rests with him or her. If the MRO finds validity in the medical explanation, the test is verified as negative. Otherwise, it is verified positive.

If the MRO agrees there is a legitimate medical explanation, fitness-for-duty considerations can still be raised with the employer.

MRO: communicating non-negative test results

The medical review officer’s process in investigating a positive, adulterated, substituted, or invalid test result must include talking to the employee directly and confidentially. A staff member under the MRO’s supervision also is authorized to make contact with the employee, but only to schedule the conversation between the employee and the MRO.

The MRO must explain to the employee that declining to discuss the drug test result will cause the MRO to verify the test as positive or as a refusal to test.

At least three attempts to reach the employee will be made. If the employee has not been reached within a reasonable time (usually within 24 hours), the MRO will contact the designated employer representative (DER) who also will make three attempts within a reasonable time to advise the employee to contact the medical review officer within 72 hours.10

It’s your right: privacy and ethics

Privacy of the donor is supremely important. A qualified medical review officer will take all steps necessary to ensure privacy, such as implementing procedures and administrative, technical, and physical controls. Access to donor information is extended only to those individuals who require it in fulfillment of their job duties.8

Employers have a right to expect and demand ethical conduct by their medical review officer. Regulations prohibit a MRO from having any relationship with a laboratory or an employer that creates a conflict of interest.11


1 Brahm NC, Yeager LL, Fox MD, Farmer KC, Palmer TA. Commonly prescribed medications and potential false-positive urine drug screens. American Journal of Health System Pharmacy. August 2010; 67(16): 1344-50.

2 Saitman A, Park HD, Fitzgerald RL. False-positive inferences of common urine drug screen immunoassays: a review. Journal of Analytical Toxicology. September 2014; 38(7): 387-96.

3. Moeller KE, Kissack JC, Atayee RS, Lee KC. Clinical Interpretation of Urine Drug Tests: What Clinicians Need to Know About Urine Drug Screens. Mayo Clinic Proceedings. May 2017; 92(5): 774-796.

4 Matriciani B, Huppertz B, Kller R, Weiskirchan R. False-negative results in the immunoassay analysis of drugs of abuse: can adulterants be detected by sample check test? Annals of Clinical Biochemistry; May 2018; 55(3): 348-354.

5 “Drug Tests Often Trigger False Positives,” MedicineNet.com, May 28, 2010.

6 “The Value and Necessity of an MRO on All Workplace Drug Test Results,” Global HR Research:

7 Federal Motor Carrier Safety Administration website. Accessed February 24, 2020.

8 Medical Review Officer Guidance Manual for Federal Workplace Drug Testing Programs, Health and Human Services Department, Substance Abuse and Mental Health Services Administration. Revised March 2018.

9 Concentra internal information

10 Legal Information Institute, Cornell Law School, 49 CFR 40.131

11 Legal Information Institute, Cornell Law School, 49 CFR 40.125