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Employers and Dilute Drug Test Results

Often employers are frustrated and confused when receiving drug test results that report out as: negative dilute.  What is a negative dilute drug test result and how can it be avoided?

So first let’s talk about what causes a negative dilute drug test result.  A dilute specimen is one where there is a greater concentration of water in a urine specimen then what would be expected for normal human urine.  Now everyone is different and can produce different levels of creatinine concentration, specific gravity and pH levels.  We must be careful and follow standards and best practices.

The creatinine concentration in the urine specimen is the primary measurement for identifying dilution and if a urine specimen contains no creatinine, it is not likely to actually be urine.  Our laboratories use standard levels of creatinine and specific gravity to determine dilution.  Most normal urine samples will have a creatinine value between 20-350 mg/dL, (milligrams per deciliter) with the norm around 100 mg/dL.  Less than 20 mg/dl is considered dilute, less the 2 mg/dL is considered not human urine.

First and foremost if you receive a drug test result report from your Medical Review Officer (MRO) that says Positive – Dilute; this is a positive drug test and a violation of your drug testing policy. The specimen was positive for the drug or drug metabolite listed.

The grey area comes with a report of Negative – Dilute.  This is not a positive and should not be interpreted as a policy violation.  There is no positive detection of a drug or metabolite in the specimen.  It basically means that the individual consumed too much water or other liquid prior to the specimen void.  This over consumption of water was either innocent or purposeful with an intent to cheat on the test.  We don’t know which from the laboratory testing. Perhaps also, a donor diluted a specimen by directly pouring water into the specimen cup before returning it to the collector during the collection process.  This of course is an attempt to cheat on the drug test.

How Can Employers Avoid Negative Dilutes?

Education is the first step.  Advise your applicants and employees that excessive consumption of water prior to a drug test can result in a dilute specimen which will require the employee or applicant to go back for another drug test.  The overwhelming majority of applicants and employees do not want to go back for a second drug test.  So it is important that they understand that normal consumption of fluids with perhaps one extra glass of water is sufficient for them to be able to urinate for the drug test.  A person that normally drinks a lot of water (over 8 glasses a day); should not drink any extra water prior to the drug test collection.

Another method to avoid negative dilute drug test results is to make sure the drug testing is unannounced.  Once an employee or applicant is notified of a requirement for a drug test the employee or applicant should proceed immediately for the drug test collection.  For random testing programs perhaps it is best practice to bring in a mobile collector to perform the specimen collections on site at your location with minimal advance notice.  Never encourage an applicant or employee to consume any excessive quantity before a drug test specimen collection. A good time for drug test collections is first thing in the morning because the urine it is typically more concentrated and will typically have a higher creatinine.

Initial education of new employees and ongoing annual education regarding the companies drug free workplace program is the key to a successful program.  This education should include a discussion of dilute specimens and how to avoid them.

What Does Your Policy Say About Negative Dilutes?

It is important to detail in your company drug free workplace policy your actions following a negative dilute drug test result.  We recommend that an employer have a section in their drug testing policy stating that another specimen be collected as soon as possible with minimum advance notice, this will help prevent negative dilute results. However, the employer may also elect to accept the negative results with the notation “dilute” from the Medical Review Officer (MRO). The company policy should be consistent in all cases.  For DOT regulated companies, there are specific requirements for your negative dilute situations with safety sensitive employees.  Click here to review sample policy language for negative dilute results for both DOT regulated and Non DOT drug testing policies.

For assistance with creation or writing of a drug free workplace policy, our experts at National Drug Screening can be of assistance.  Contact National Drug Screening or call 866-843-4545.