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Negative-Dilute Results

With pre-employment drug testing, a negative-dilute specimen is a urine specimen that has a greater concentration of water than that of a normal urine specimen. Dilution is the process of reducing the concentration of drug or drug metabolites. This can be either purposeful or accidental.

It is possible that a specimen could be negative-dilute due to unintentional over-hydration.
Some individuals are used to drinking a certain amount of fluids each day in pursuit of a healthy lifestyle. There also may be nervousness or concern by the subject of not being able to provide a sample at the time of the drug test.

However, it is also possible that the donor has intentionally over-hydrated, or water-loaded, to avoid the detection of the presence of drugs in the specimen. Because the reason is unclear at
first, there tends to be a bit of ‘gray area’ concerning specimens that come back dilute.

It is important to note that a negative-dilute specimen is not the same as a positive result. Dilute specimens that are positive are not reported as positive-dilute, they are reported as positive.

Your company policy should spell out what to do in the case of a negative-dilute test results.
Some put policies in place to refuse to hire, others accept it as a negative result, or most times they send the subject back for a 2nd test as soon as possible. In the cases where a 2nd test is offered, if the 2nd test comes back negative-dilute, some companies choose to accept the negative-dilute as a negative result. While others have a policy that a 2nd negative-dilute sample, or otherwise invalid specimen (e.g. out of temperature range), will result in a refusal to hire. Whatever the company policy, it is important to be consistent across the board to avoid any compliance related issues.

Tips to help subjects avoid a negative-dilute test result:

  • schedule the drug test for first thing in the morning
  • avoid caffeinated beverages such as coffee or soda
  • consume minimal fluids for a six-to-eight hour period before collection
Sherry Kocienski