How false drug test results put children at risk

This clinical case series examines false-positive and false-negative results in urine drug screening of young children (0-5 years) using confirmatory testing with gas chromatography-mass spectrometry (GC-MS). The study tracked 14 pediatric patients who initially tested positive on immunoassay urine drug screens—a rapid but less accurate screening method. When these results were confirmed using the more reliable GC-MS technique at a reference laboratory, the findings revealed a critical problem: many initial positive results were inaccurate, caused by cross-reactivity of the immunoassay antibodies with unrelated compounds, or by substances that were completely missed during initial screening.

The research identified numerous substances confirmed through GC-MS, including cocaine metabolites, prescription medications like lorazepam and sertraline, and notably, cannabis metabolite 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH). The study demonstrates that confirmatory testing directly influenced clinical management decisions and supported child protection interventions in cases of suspected neglect, accidental poisoning, or environmental exposure. This finding has profound implications: relying solely on initial immunoassay screening without confirmation can lead to incorrect diagnoses, inappropriate medical treatments, and potentially wrongful child protection actions based on false-positive results.

The research underscores the critical importance of using definitive analytical methods like GC-MS before making clinical decisions or legal determinations in pediatric toxicology cases. For cannabis specifically, this study highlights how THC metabolites can be accurately identified and distinguished from interfering substances only through confirmatory testing, ensuring that positive results truly represent actual exposure rather than false alarms. The findings advocate for stronger protocols that require confirmation testing before any clinical action or child protective services involvement.