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To keep transportation aligned with federally mandated laws, DOT drug and alcohol testing is obligatory for truckers and transportation companies. By making your company comply with the Department of Transportation (DOT) you not only promise a safe work environment but your truckers/drivers, clients, and public safety as well.

When a driver is instructed to go through the DOT drug testing program for the first time after a drug violation or being selected for random drug testing, it must come to mind how drug testing would take place or the procedure. Following is a case study where an employee is negatively tested for DOT urine test and the urine sample shows a dilution:

Negative diluted urine drug test

1.Lab Findings:

  • Negative and diluted
  • Creatinine Level: 6.4 mg/dL

2.Lab Report

A computerized report after being generated sent to Medical Review Officer (MRO).


The employee may not be called by MRO for a dilute negative urine report. It may be concluded as the employee must have taken a lot of water to reduce the concentration of the drug or may use some kind of diuretics before the collection of a urine sample.

4.MRO Report

The company is directed to collect another sample of the same employee immediately.

5.Second Lab Report

Negative and diluted

Creatinine level: 7.0mg/dL


MRO may conduct a direct interview with negatively tested employees to investigate the possible two reasons behind negative urine test.

The MRO looks for if the employee is using any prescribed diuretics or if there was an unintentional take of water or if it was taken to produce a sufficient quantity of sample.

If dilution was due to the prescribed medications (diuretics) then the employee is reported negative by the MRO also if the negatively diluted urine drug test was due to excessive water consumption without any specific reason the employee is again scheduled for another drug test immediately while strictly directed to not drink excessive water before the sample collection.

Read about: Fake pee and how it impacts the results

7.Third Lab Report

Negative results.


Finally, the negative results are reported by the MRO to the company for the employee being selected for the drug test.

When the creatinine concentration for a negative-diluted urine sample is between 2.0 and 5.0 mg/dL, DOT directs (CFR Part 40) an immediate collection of a second sample through a directly observed collection process.

Transportation companies can choose among DOT drug testing services provided by goMDnow that provide you with DOT-approved labs and medical analysis of the results. This medical evaluation by a Medical Review Officer (MRO) ensures a legal drug test result and lessens the risk of accountability for the company.

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