Drug testing is commonly performed for medical care as well as for workplace and forensic purposes. The most common specimen for routine drug testing is urine, although saliva (oral fluid) has been increasing in popularity. Specimens used in more specialized situations include blood, hair, umbilical cord tissue, meconium, and sweat. Challenges with drug testing arise with both screening and confirmatory tests. Screening tests are vulnerable to false positives and false negatives. Clinicians ordering testing may not be appear of limitations of drug screens or what compounds cross-reacts with a particular screen. Confirmatory testing provides more definitive results, but interpretation of test results can be challenging. Less commonly used specimens (e.g., hair, umbilical cord, meconium) have their own strengths and challenges. The purpose of this session is to provide an overview of drug testing and illustrate key information that can help guide test selection and interpretation. Illustrative cases will be interspersed throughout the session.
Learning Objectives:
- Define the limitations of drug of abuse screening assays including false positives
- Distinguish between screening and confirmatory tests for drug testing
- Explain the common specimens used for drug of abuse testing (urine, blood, oral fluid, hair, meconium, umbilical cord)
