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Toxicology screens are often used in healthcare settings to detect the presence of particular chemical substances or their metabolites by examining biological specimens (McNeil & Cogburn, n.d.). Common biological specimens used for drug testing include urine, blood, saliva, hair, nails, sweat, breath, and meconium (Hadland & Levy, 2016). These biological matrices possess different rates and durations of excretion that result in different detection windows. In general, blood and saliva have the shortest detection windows, while urine typically has a detection window of hours to days, and hair and nails have the longest detection windows ranging from months to years (Education, n.d.; Hadland & Levy, 2016).
Among all of the biological specimens, urine is the most preferred and most widely used for drug testing due to the ease of collection, the wide availability of tests, and its good detection window (Education, n.d.). The concentrations of drug metabolites also tend to be higher in urine than in serum samples (Education, n.d.). However, urine is easy to adulterate, does not identify the frequency of dosing, and does not reliably estimate the drug dose taken (Education, n.d.).
Urine drug screens (UDSs) are often used in the workplace to screen for illicit drug use. The employee is specifically made aware that the UDS is being performed, the implications of its results and without coercion consents to the performance of the test. These forensic drug tests are meant to stand up to a legal challenge and must meet the rules of chain of custody, secure storage of samples, stringent methods of validation with the aim of minimizing false positive results. The laboratory personnel in a forensic laboratory are subject to rigorous certification programs and generally have training in chemistry or forensic science that include chain of custody and medical legal requirements. The applications for forensic urine drug testing include pre-employment testing, ‘for cause’ testing (in response to an on-the-job accident), school testing, competitive sports and in the criminal justice system child custody cases and Department of Transportation testing.
In the clinical setting, however, UDSs are often used in ED settings when assessing patients with significant altered mental status, trauma, or seizure, or in non-emergency settings to monitor drug dependency and validate any concern for drug overdose (Moeller et al., 2008). In contrast to the forensic UDS, ED patients are generally unaware that drug testing was conducted and neither informed consent nor federally regulated guidelines for validation are required. Their ED consent is presumed to cover all relevant medically appropriately care. The UDS is included with blood work, EKG, blood gases and radiology. In addition, the interpretation of UDS results is compounded by many clinical factors, such as cross-reactivity issues or the presence of lower cutoff values compared to those in the workplace setting (American Society of Addiction Medicine, n.d.; Moeller et al., 2008; Raouf et al., 2018). Moreover, many ethical principles are often not obeyed in current UDSs, and there is generally a lack of education on the interpretation of UDS results.
This article provides an overview on the current state and limitations of UDSs performed in the clinical setting, factors that may affect the interpretation of UDS results, and ethical issues associated with the current UDS. The implications of false-positive UDS results and routine UDSs on patients are also considered. The article also presents three clinical vignettes on the impact of false-positive UDS results on the patients’ care and reputation. Finally, the article offers some recommendations on moving forward with the current UDS process in the clinical setting. Clinicians should be aware of the limitations of the current UDS guidelines and use the UDS sensibly and ethically to maintain the fiduciary relationships they have with patients and not affect their quality of care.