Toxicology services are in high demand, but even as startup labs focused on toxicology break into the market and established clinical labs look to expand their offerings, maintaining the highest standards of testing while also running efficient operations remain essential given the far-reaching consequences of toxicology testing. Before labs dive (or dive deeper) into the booming drug testing market, they will do well to conduct a strategic cost-benefit analysis to en-sure better financial performance and long-term success.
Whether a lab is just starting toxicology testing or expanding its offerings, the driving consideration in determining the most appropriate solution turns on this question: What purpose will the toxicology lab serve?
The purpose and complexity of testing dictate the certifications and practices labs must follow. For example, toxicology evaluations in clinical settings may have legal implications under cer-tain circumstances, especially when it comes to pregnant women, children, and newborns. However, unless ordered by law enforcement or the judicial system, toxicology testing in clinical laboratories falls under CLIA regulations. Some states or institutions may have additional requirements.
Non-forensic toxicology testing such as for pain management and non-Department of Transportation workplace screenings also fall under CLIA regulations. Labs can elect to use chain of custody forms and abide by other restrictive procedures consonant with legal system standards—like setting cutoff concentrations for positive results—but aren’t under regulatory requirements to do so. In contrast, labs that perform strictly forensic toxicology testing are CLIA-exempt. Even so, they may be subject to some accreditation requirements, such as the College of American Pathologists Forensic Drug Testing program, which provides accreditation for laboratories performing workplace drug testing.
What’s on the Menu?
A lab’s test menu also needs to reflect the overall purpose of its toxicology services. Clinical laboratories that perform limited toxicology testing for diagnostic, management, and prognostic purposes already understand the concept of an essential toxicology menu. This menu usually includes screening for the major classes of abused drugs (amphetamines, barbiturates, benzodiazepines, cocaine, opiates, propoxyphene, and tetrahydrocannabinol), alcohol, and common therapeutic drugs like acetaminophen, salicylates, digoxin, antidepressants, and aminoglycosides.
Laboratories offering advanced testing services may extend this core menu to hundreds of drugs and metabolites. A lab’s director ultimately determines how deep its testing menu should be, based on the testing volume and financial considerations for each drug of interest.
From Screening to Confirmation
The testing menu in turn imposes needs for specific instrumentation and methodologies. Point-of-care drug tests are broadly available and include immunoassay-based devices for rapid qualitative urine-based evaluation of commonly abused drugs, together with limited evaluation of a specimen’s quality. However, these devices generally are only suitable for settings with low test volumes.
Labs with higher testing volumes need to consider carefully their throughput and instrumentation for screening. Although toxicology screening can be accomplished very quickly, considering immunoassays’ limited specificity and cross-reactivity issues, the results are considered presumptive and need to be confirmed with a more sensitive and specific method less prone to interferences, such as various mass spectrometry (MS) technologies.
MS offers many ad-vantages, including accurately quantifying drugs, discriminating between different compounds in the same drug class, discerning therapeutic versus abuse level concentrations, and detecting compounds at very low concentrations. Nevertheless, the confirmatory process not only involves more sophisticated instrumentation, but also is more labor intensive and has a longer turnaround time.
Most small and large laboratories find drug screening clinically and financially feasible, but confirmatory and advanced toxicology testing for these facilities is more challenging. Many use reference laboratories for these purposes; however, larger laboratories serving broad population bases need to consider the turnaround time of outsourcing. This underscores the necessity of a cost-benefit analysis for labs considering confirmatory and advanced toxicology services.
Time for an MRO?
To meet the highest standards of toxicology testing, labs need to not only render analytically accurate results but also interpret those results correctly. The latter, in the context of a patient’s clinical presentation and medical and medication history, can be very challenging. While qualified laboratory personnel can assure high quality analytical performance, procedures for interpreting toxicology results often require a higher level of expertise.
Both the Substance Abuse and Mental Health Services Administration and Department of Health and Human Services highly recommend involving medical review officers (MRO), who have training, certification, and knowledge regarding the pharmacology and toxicology of illicit drugs, testing, and instrumentation. MROs not only ensure correct interpretation of toxicology reports, but also support lab efforts to provide quality toxicology services. They review all positive, adulterated, substituted, and invalid test results before the final results report, represent a link between all participants in the drug testing process—donor, collector, testing lab, and ordering institution—and also play a key role in interfacing with the legal system as needed.
The decision to engage an MRO, along with choice of testing menu, appropriate regulations to follow, and choice of test menu, instruments, and methods all flow from the crucial question of a lab’s purpose.
Alina G. Sofronescu, PhD, NRCC-CC, FACB, is medical director of clinical chemistry and the toxicology laboratory and an associate professor of pathology and microbiology at the University Nebraska Medical Center in Omaha. Email: [email protected]