Common Drug Test Questions and Problems

Employers conducting employee drug testing have questions or confusion about issues that turn up in the workplace drug testing process. The following drug testing problems will be discussed in this article.

It is typically the DER or Designated Employer Representative at the company that deals with these issues.  This is the company official that is in charge of the drug testing program.

Negative Dilute Result

When you get a drug test result back and it says Negative Dilute, what does this mean? The specimen has tested at the lab and the result is negative. Also, for this specimen the specific gravity and creatinine levels are abnormal indicating a urine specimen is dilute. This is not a positive result, not a refusal and not a violation of a drug testing policy. The best practice for this situation is to:

Learn more about a Negative Dilute Drug Test Result on our blog post and video.

Shy Bladder

A shy bladder is when your applicant or employee cannot void a sufficient quantity of a urine specimen for the lab to do the drug testing. This results in the donor going into a shy bladder process. This process can take up to 3 hours and the donor can consume up to 40 ounces of water. The donor cannot leave the testing facility during this 3-hour period, or this will be a refusal. If after 3 hours if the donor sill cannot sufficient quantity of a urine specimen, the donor can be afforded a medical evaluation to see if there is a medical explanation for this shy bladder. If the donor refuses the medical evaluation this is a refusal to test and a violation. If the physician conducting the medical evaluation finds no medical explanation, this is a refusal to test and a violation.

Review our blog posts on shy bladder:

Temperature Out of Range

When a urine specimen is collected for a drug test; the temperature of the specimen should be between 90 and 100 degrees to be valid. There is a temperature strip on the urine collection cup to determine this. If the specimen temperature is not within 90 and 100 degrees; there is an indication the specimen did not come out of the donor’s body.

The temperature out of range situation requires that this first collection be completed and then a second collection be conducted under a direct observation protocol. Both specimens are sent to the lab, but it is the result of the second specimen collected that will be the official result.

If the donor refuses this second collection under direct observation, this is a refusal to test and a violation. It is important to note that the direct observation procedure is required for Department of Transportation (DOT) testing programs but not recommended for non-regulated testing programs. (check state laws and company policy). Complete documentation and paperwork should be completed for all aspects of every attempted specimen collection.

Direct Observation Drug Test

As indicated above, a direct observation is conducted when a specimen collected is out of temperature range. Direct observation is also conducted when the specimen appears to have been tampered with or when there is specific indication of attempting to tamper with a specimen. Also, all DOT drug tests with a reason for test as return to duty or follow-up are required to be direct observed.

Check out our blog post: What Are The DOT’s Direct Observation Procedures?

Canceled Drug Test Result

As the designated employer representative (DER) for your company in charge of the drug testing program; you might get back the results of a drug test as Cancelled. This can indicate several issues:

A canceled test result is neither a negative nor a positive. To get a person into a DOT safety sensitive position, a negative result is needed so a new test would be needed. For other types of testing not requiring a negative result to enter or re-enter a position the Medical Review Officer (MRO) simply cancels the test and leaves it as is.

Invalid Drug Test Result

An invalid drug test result is different from a canceled drug test result. This result is also neither a negative nor a positive. The invalid drug test result will go through MRO review to determine if there is a medical explanation as to why the lab cannot provide a scientifically supportable result. The lab reports a urine specimen invalid when the specimen contains an unidentified adulterant, contains an unidentified interfering substance, has an abnormal physical characteristic, or has an endogenous substance at an abnormal concentration that prevents the laboratory from completing testing or obtaining a scientifically supportable drug test result. In some cases, based on the MRO review of the invalid specimen result, there may be a requirement for a second collection and sometimes under direct observation when there is no medical explanation.

Drug Test Refusal

A refusal to test is serious business, it is a violation and can have the same consequences as a positive drug test. Many companies require an immediate termination of employment when an employee refuses a test required by the company. As the designated employer representative (DER) for your company in charge of the drug testing program; it is very important that you understand refusals to test and your responsibility in many instances to make the official determination of the refusal.

Refusals that occur at the collection site are reported to the DER for the DER to make the official determination. Review our FAQ’s on:

What Is A Refusal To Take A DOT Drug Test, And What Are The Consequences?

What Is A Refusal To Take A DOT Alcohol Test, And What Are The Consequences?

Follow the above DOT regulations on refusals also for non-regulated testing for best practices.

Review our comprehensive handout for Refusal to Test. This will tell you who is the decision maker for each type of refusal event.


It is important for the designated employer representative (DER) to be knowledgeable of the drug testing process, regulations involved and best practices. Every test result and paperwork should be carefully reviewed. Learn more > What Is A DER Or Designated Employer Representative?

a doctor looking at a urine sample
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