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11Oct

Limits of Interpreting A Drug Test

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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 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 a 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) Quaifications of medical Review Officers (MRO’s) in Regulated and Nonregulated Drug Testing. Departments: ACOEM Consensus Opinion Statement



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What you need to know about meconium collection.

by Michelle Lach, MSIMC

Meconium is the first stool of a newborn infant. It is produced in utero and consists of materials such as epithelial cells, bile, mucous, and more. In most newborns, meconium is generally passed in the first day or so of life, has no odor, and appears as a very dark, tar-like substance. This helps distinguish meconium from the next phase of passage called transitional stool. 

Transitional stool will start to have an odor and present with a more brown, green, or yellow color as the newborn starts digesting milk. When drug testing the meconium of a newborn, it is important to note this difference since only meconium is created during gestation and transitional stool is created after birth. Collection of any stool other than meconium for drug testing purposes may result in a rejected specimen.  

Unlike umbilical cord tissue, drugs are not distributed uniformly throughout the meconium specimen (see Figure 1). Because of this, the collection of the entire mass of meconium is highly encouraged to assure that there will be enough specimen to test, and that the maximum window of drug detection is achieved. It can take multiple passages of meconium before the newborn begins the transitional stool phase. 

We require a minimum of 3 grams of meconium to be able to properly run our tests, so collecting the entire passage of meconium from newborns that have been exposed to substances of abuse is highly critical since they tend to have lower birth weights and create less specimen in the first place. If there is not enough specimen to run the test, the results are reported out as QNS. Quantity Not Sufficient (QNS) is a result of not having a sufficient quantity (volume) of specimen to test for the panels ordered. 

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Substance Vol 8 Iss 1

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NeoTox Vol 7 Iss 3

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