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
Des Plaines, IL – United States Drug Testing Laboratory, Inc. (USDTL), a forensic laboratory specializing in drug and alcohol testing using advanced specimens, has released a new assay to detect zolpidem (Ambien®) use in fingernail and hair specimens. Previously available only in urine and oral-fluid specimens, zolpidem testing in fingernails and hair offers forensic drug testing professionals new, powerful tools to meet their drug testing needs.
Since its approval in 1993 for the treatment of insomnia, zolpidem has become one of the most popular and most prescribed sleep aids. Zolpidem is a sedative-hypnotic medication that affects the same areas of the brain as benzodiazepines. In 2011, 39 million prescriptions for zolpidem products were written in the United States. 
Zolpidem use carries some risks of harm, especially when taken in combination with other substances. The number of emergency department visits related to zolpidem grew by 136% from 2004 (12,792) to 2011 (30,149).  Other substances were involved in 57% of those ED visits, including benzodiazepines (26%), narcotic pain relievers (25%), and alcohol (14%). 
The development of zolpidem testing is driven by USDTL’s ongoing commitment to be a leader in substance abuse and alcohol detection. Zolpidem testing in fingernails and hair will be available on October 1st, 2014.
USDTL has made significant breakthroughs in detecting alcohol and other substances of abuse. They offer a wide range of testing services and specialize in hard to detect substances of abuse, customized assays, and advanced drug testing specimens.
1. IMS, Vector One: National (VONA) and Total Patient Tracker (TOT). Year 2011. Extracted June 2011.
2. Substance Abuse and Mental Health Services Administration, Center for Behavioral Health Statistics and Quality. (May 1, 2013). Emergency Department Visits for Adverse Reactions Involving the Insomnia Medication Zolpidem. Rockville, MD.
3. Substance Abuse and Mental Health Services Administration, Drug Abuse Warning Network, 2011: National Estimates of Drug-Related Emergency Visits. HHS Publication No. (SMA) 13-4760, DAWN Series D-39. Rockville, MD: Substance Abuse and Mental Health Services Administration, 2013.
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