Understanding Diluted Drug Test Results: What You Need to Know

At Central Drug Testing, we understand the importance of accurate and reliable drug testing results. One issue that occasionally arises is when drug tests come back as diluted. Dilution occurs when the concentration of a substance in the urine sample is lower than expected, which can potentially affect the accuracy of the test results. In this blog post, we'll delve into the intricacies of diluted drug test results, including when they can be reported and the various outcomes that a Medical Review Officer (MRO) may determine. A diluted urine drug screen means there is too much water in the urine. Generally, a person is unable to drink enough water to cause this to happen and it is the result of the donor placing fluid/water in the solution after collecting it but before turning it in. This is why the toilette water has blue dye added to the water before sending a donor to the bathroom. An easy way for non-dot employers to completely avoid diluted samples is to use a saliva test instead of a urine test. Every saliva test is obtained under direct observation.

When can diluted drug test results be reported?

Diluted drug test results can be reported when the sample provided by the individual undergoing testing has a creatinine concentration of less than 20 mg/dL and a specific gravity of less than 1.003. Creatinine is a waste product generated by muscles, and its concentration in urine is a marker used to assess the integrity of the sample. Specific gravity, on the other hand, measures the density of urine compared to water, indicating the concentration of substances in the urine.

Understanding MRO Reporting Options:

  1. Dilute Negative:

    • A dilute negative result indicates that the sample provided was diluted but did not contain any detectable levels of the targeted substances. In this case, the MRO may advise retesting to ensure accurate results. Many times, the next test is done under direct observation. Direct observation means a person will be in the bathroom with the donor to be sure the sample isn’t tampered with after collection.

  2. Dilute Positive:

    • A dilute positive result suggests that the sample was diluted, but traces of the targeted substances were still detected. The MRO will proceed with the verification process to determine if there is a legitimate medical explanation for the dilution or if further action, such as disciplinary measures or treatment referrals, is necessary.

  3. Dilute Invalid:

    • In cases where the sample is too diluted to produce reliable results, the MRO may declare the test as dilute invalid. This could be due to intentional dilution or excessive fluid intake by the individual undergoing testing. In such instances, the MRO may request a retest with strict guidelines to ensure the integrity of the sample. Once again, this may be an observed collection(see above).

Scientific References:

  1. Jones AW. Evidence-based survey of the elimination rates of ethanol from blood with applications in forensic casework. Forensic Sci Int. 2010;200(1-3):1-20. doi:10.1016/j.forsciint.2010.03.023

  2. O'Connell TM. The complexities of urine drug testing interpretation. J Pain Palliat Care Pharmacother. 2010;24(4):359-365. doi:10.3109/15360288.2010.529064

  3. Moeller KE, Kissack JC, Atayee RS, Lee KC. Clinical interpretation of urine drug tests: what clinicians need to know about urine drug screens. Mayo Clin Proc. 2017;92(5):774-796. doi:10.1016/j.mayocp.2016.12.007

Conclusion:

Diluted drug test results pose challenges in interpreting the validity and accuracy of test outcomes. By understanding when diluted results can be reported and the various reporting options available to MROs, we can ensure that drug testing processes remain reliable and effective. At Central Drug Testing, we are committed to providing comprehensive drug testing solutions that prioritize accuracy, integrity, and fairness. If you have any questions or concerns about diluted drug test results or any other aspect of drug testing, don't hesitate to reach out to our experienced team.