Urine| Hair Follicle | Oral Fluid | Blood | ETG
Hair testing is increasingly recognized as a robust method for detecting drug and alcohol consumption. Hair strands capture biomarkers within their fibers, offering an extended-term record of substance use. When procured near the scalp, hair can reveal alcohol and drug consumption for nearly a 3-month period. The collection process is straightforward, the alteration is somewhat challenging, and it facilitates easy transport.
A sample measuring 1.5 inches, with around 200 hair strands (equivalent to a #2 pencil), collected nearest to the scalp, yields 100mg of hair, the optimal sample size for screening and confirmation. For EtG, additional analyses, and tests beyond 10 panels, a specimen of 150mg is advised. It is suggested to weigh the specimen using a jeweler's scale. In the absence of scalp hair, a similar quantity of body hair may be utilized. By head hair, we mean exclusively scalp hair. Body hair encompasses all other varieties (facial, axillary, etc.).
Process Overview
The laboratory processing of a drug test result encompasses four core stages: Accessioning, Screening, Extraction, and Confirmation.
In Accessioning, the sample undergoes initial processing into the lab's system. This stage ensures the sample's proper sealing and shipping, assigns a unique LAN (Laboratory Accessioning Number), and completes any additional data input not available via an electronic chain of custody system.
Screening includes a preliminary rapid assessment for drug abuse. While it serves as an economical method to dismiss drug presence in most samples, court validity requires confirmation of positive screens. Samples with a presumptive positive outcome in Screening need secondary confirmation.
For samples presumptively positive in Screening, additional hair is drawn from the initial sample for the Extraction phase. Here, drugs are extracted from hair at notably lower concentrations than other methods (like urine or oral fluid), rendering hair drug screening the most intricate methodology to execute.
Confirmation of positive screening results is achieved via GC/MS, GC/MS/MS, or LC/MS/MS analyses. Prior to confirmation, all presumptive positive samples undergo washing as needed. The comprehensive laboratory process from Accessioning to Confirmation is reviewed under the CAP (College of American Pathologists) Hair designation and complies with ISO / IEC 17025 standards.
Advantages of hair drug testing:
Limitations:
Note: Although sometimes called "hair follicle tests," the test actually examines the hair strand, not the follicle under the scalp.
