10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
An aircraft mechanic's DOT urine test is confirmed positive for oxycodone and oxymorphone. A verified oxycodone prescription explains the findings, and the MRO reports the test negative. The mechanic also describes falling asleep during safety-sensitive work. The next day, the prescriber contacts the MRO but cannot resolve the medication-related safety risk. Which communication to the employer is now appropriate?
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Correct answer: C - A separate written notice describing the specific safety concern, without changing the negative result
Question 2
A worker disputes a methamphetamine-positive urine result, saying, 'My prescription must be interfering with the test.' Analyte-specific confirmation detects both methamphetamine and amphetamine. Additional stereoisomer testing identifies only the L forms of both compounds. Which explanation fits this pattern?
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Correct answer: A - Metabolism of prescribed selegiline
Question 3
A transit employee's random DOT urine test is negative-dilute: creatinine 12 mg/dL and specific gravity 1.0024. Collection was uneventful. The employer's previously announced policy is not to repeat random negative-dilute tests unless DOT requires it, and no other recollection trigger is present. The MRO's disposition should be:
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Correct answer: D - Report negative-dilute without directing a recollection
Question 4
Two minutes after receiving 55 mL of urine, a DOT collector reads a specimen temperature of 30°C. The employer's standing order calls for a directly observed urine collection in this situation. The employee cooperates and produces a sufficient second specimen. How should the collector handle the specimens?
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Correct answer: B - Process and send both collections, cross-referencing their separate CCFs
Question 5
A truck driver's DOT urine test is confirmed positive for marijuana metabolite. The driver denies marijuana use and produces a receipt for an over-the-counter CBD oil labeled 'THC-free.' The interview identifies no legally valid prescription that explains the result, and the laboratory confirms analytical and specimen integrity. How does the CBD explanation affect verification?
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Correct answer: B - It does not provide a legitimate medical explanation; verify positive
Question 6
A DOT urine specimen was verified positive for cocaine after benzoylecgonine was confirmed at 240 ng/mL. At the employee's request, a second HHS-certified laboratory tests the split specimen. Its validated reconfirmation method unequivocally identifies benzoylecgonine at 65 ng/mL, with acceptable quality controls and no validity concerns. The employee argues that 65 is below the 100 ng/mL primary confirmation cutoff. What does the split finding establish?
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Correct answer: C - The cocaine finding is reconfirmed; the primary cutoff does not govern split testing
Question 7
During one calendar quarter, an MRO's supervised staff review 12,600 negative DOT results. Thirty of those CCFs require corrective action. For the MRO's personal quality-assurance review, what is the minimum compliant workload for that quarter?
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Correct answer: A - 500 CCFs total, including all 30 that required corrective action
Question 8
Forty-six hours after the MRO notifies an employee of a verified positive DOT drug test, the employee telephones to request split-specimen testing. The employee cannot afford the laboratory fee and will not sign a reimbursement agreement. The employer tells the MRO to hold the request until payment is arranged. The MRO should:
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Correct answer: D - Immediately direct shipment to a second HHS-certified laboratory without a payment condition
Question 9
A DOT laboratory reports urine morphine at 8,400 ng/mL and no detectable 6-acetylmorphine. The employee has no prescription for an opiate. The MRO completes the medical interview and review but finds no clinical evidence or history of unauthorized morphine, codeine, or heroin use that could account for the result. Which verification is required?
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Correct answer: C - Negative, because the required additional clinical evidence has not been established
Question 10
Two separately tested aliquots of a urine specimen have creatinine concentrations of 1.4 and 1.6 mg/dL. Their specific gravities are 1.0120 and 1.0130. The laboratory finds no other specimen-validity abnormality. Under the HHS urine validity criteria used by the certified laboratory, which classification is supported by this combination?
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Correct answer: C - Invalid because creatinine and specific gravity are inconsistent
What's on the MRO exam
The Medical Review Officer Certification (MRO) exam is organized into 1 knowledge domains. These free practice questions are drawn from across them so you can see where you're strong and where to study:
Medical Review Officer Roles, Procedures, Regulations and Drug Testing Practices
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The full bank has 1,020 more MRO questions with explanations.