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Dilute Specimens in Employer Drug Testing

03 Jan 2016

If a positive test result is also reported as dilute, the positive result stands and procedures for reporting a positive test should be followed. 

What does dilute mean? Perhaps the donor drinks a lot of water, perhaps the donor is trying to cheat the test.  When you get a drug test result that says Negative Dilute – I am sure you get confused. 

A dilute specimen, by definition, is a urine specimen that has a creatinine of between 2mg/dL and 20 mg/dl and a specific gravity greater than 1.0010 but less than 1.0200. These 2 tests are routinely performed on every urine sample that is tested at the Lab. If the specimen meets the above two criteria, it is reported as a "Dilute specimen". When a urine specimen is "dilute" and negative, it is possible that drugs in their system may not have been detected. 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 additional negative dilute results. However, the employer may also elect to accept the negative results with the notation "dilute" from the lab. The company policy should be consistent in all cases.  

Under DOT regulations, if a negative test is also reported as a dilute with a creatinine level greater than 2mg/dL but less than or equal to 5mg/dL, the donor must be directed to supply a second specimen under direct observation. The donor must be directed to do so immediately.  The MRO will make this determination and request to the DER.  

For non-DOT drug testing program this provision for this type of “super-dilute” (creatinine level greater than 2mg/dL but less than or equal to 5mg/dL) and the requirement of a direct observation second collection must be stated in a written company drug free workplace policy.  It is not recommended to have direct observation collections performed unless provided for in the written company drug free workplace policy. 

If a negative test is also reported as dilute with a creatinine level greater than 5mg/dL, the C/TPA should consult the employer’s policy to determine their policy on dilute specimen.

There are two ways to handle a negative dilute specimen result with a creatinine level greater than 5 mg/dL, but the employer must treat all employees the same. For this reason, the C/TPA should ensure that the employer addresses this issue in their company policy. Different options can be used for different types of tests (i.e., recollect on pre-employment and return-to-duty, but not for random), but every individual that is found to have a dilute specimen on a pre-employment test must submit a second specimen. 

The first option would be to accept the negative result. The second option is to collect another specimen under normal collection procedures (direct observation is not allowed). The result of the second specimen would become the test result of record. If the second specimen is also dilute, no further tests are authorized, and the second negative dilute result stands. 

For assistance in handling dilute specimens or to implement or revise your drug free workplace drug testing program, call 866-843-4545.