December 28, 2015 | From the Lab Bench

Not All Assays Are Created Equal

By Jill Warrington, MD | Burlington Labs Chief Medical Officer

Recently, I spoke with a clinical provider who needed some assistance in interpreting the results of the drug screen he ordered for a patient. This case highlights the importance of “knowing what you’re getting” when ordering a qualitative (positive/negative) drug screen.

This clinician was managing the care of a young woman in an MAT program who was being prescribed both methadone and oxycodone. The provider ordered a urine toxicology screen using an instant POC cup and the patient’s opiates came back negative.

At this point, the provider was faced with three possible conclusions:

  1. She is noncompliant.
  2. She is diverting.
  3. She is a rapid metabolizer and these compounds were cleared prior to collection.

Unfortunately, the clinician couldn’t rule any of these options out based on the toxicology report alone. Some opiate panels (in both instant “dipstick” tests and in some laboratory-based screens) effectively do not detect either oxycodone or methadone, due to high cutoff levels for those substances.

For this reason, it’s important to know what the cutoff levels are for the assays included in your drug screen, whether you’re using an instant POC cup or sending the sample out to a laboratory. If you’re unsure, it’s a good idea to ask your lab in advance for the cutoff levels associated with each type of assay they offer. Then, use this information as a reference to help you choose the test that will give you the information you need.

Another option for the clinician in this particular case, once the results came back inconclusive, would be to order a confirmation test from the same urine sample. Within a few days, he’d have a follow-up quantitative report showing the exact amounts of drug compounds and metabolites that were in his patient’s urine at the time of her office visit.

Any treatment provider who has questions about how to interpret drug-screen or confirmation-test results, or how to order the most helpful test profile for a particular situation, is always welcome to call our lab team for guidance. 


Read more articles from our January/February 2016 issue of our newsletter, "TheBuzz":

Massachusetts Lab Increases Capacity with Facility Move
My Story: I Gave Up a Kidney -- and Gained a Friend
Compassion in Action: Adopting Families for the HolidaysPolar Express
Event Educates, Unites Families Impacted by Addiction
"Continuing Ed" with Ed Baker: Nice to Meet You!
Partner Profile: Richard Winant, Kelly House, Wakefield MA
Drug Trivia: Alcohol Use During Pregnancy
Patient Services News: Burlington Extends HoursRutland Ribbon-Cutting

Or, click here to download the full PDF.