Limits of Interpreting A Drug Test
By: Kelly Hack, Content Writer
There are many variables regarding the analyses of substance abuse testing. Clients will often ask about specifics pertaining to the determination of time, dose and frequency when detecting substance(s) of abuse.
When testing a reservoir matrix- a material or substance which can accumulate and retain drug and alcohol biomarkers (eg., urine, blood, hair, nail, umbilical cord, or meconium, etc.), the reported quantitation of a drug or its metabolite cannot be used to determine when/if a specific substance was used, how much of a substance was used or how often a substance was used. Test results show only if a substance was detected or not detected.
A specimen’s window of detection provides an estimated timeframe for detecting substance(s) of abuse. Based on extensive research studies, the generally accepted windows of detection for specimens used in our testing are as follows:
- Scalp Hair- Up to approximately 3 months prior to collection.
- Fingernail- Up to approximately 3-6 months prior to collection.
- Umbilical Cord- Up to approximately 20 weeks prior to birth.
- Meconium- Up to approximately 20 weeks prior to birth.
- Urine- Up to approximately 2-3 days prior to collection.
- Blood (PEth)-May be up to approximately 2-4 weeks prior to collection.
It is important to know that the interpretation of drug testing results may be determined by a Medical Review Officer (MRO). A Medical Review Officer is a licensed physician (MD or DO) who has knowledge of substance abuse disorders and has the appropriate medical training to interpret and evaluate an individual’s positive test result together with his or her medical history and any other relevant biomedical information.1This is an incredibly important aspect of drug testing. A laboratory can detect substances, but an MRO may be used to interpret what that detection means.
1. Journal of Occupational and Environmental Medicine: (January 2003-Volume 45-Issue 1-p 102-103) Qualifications of Medical Review Officers (MRO’s) in Regulated and Nonregulated Drug Testing. Departments: ACOEM Consensus Opinion Statement
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