The role of rapid chromatographic immunoassay tests in acute poisoning: two case reports and literature overview
Journal
La Rivista Italiana della Medicina di Laboratorio
Date Issued
2026-03-22
Author(s)
KOSTADINOVSKI, Kristin
DOI
10.23736/S1825-859X.25.00310-X
Abstract
This report through the presentation of two case studies highlights the common problem with false-positive urine drug screen faced by many physicians to the emergency and toxicology departments. Case 1: a 29-year-old male patient was admitted after acute poisoning with analgesics/antipyretics (Caffetin Cold, Caffetin); diazepam; amlopin. Case 2: a 56-year-old female patient was admitted with impaired consciousness. According to the data obtained from the patient’s family they suspected that she took the following drugs: Zanfexa, Zalasta and Diazepam. A rapid chromatographic immunoassay urine test was performed in both patients for the following substances: opiates, amphetamines, metamphetamine, MDMA (3,4-methylenedioxymethamphetamine), oxycodone, phencyclidine, cocaine, methadone, barbiturates, cannabinoids, benzodiazepines, tricyclic antidepressants, and tramadol. Case 1 was positive for opiates, benzodiazepines and amphetamines. Gas chromatography mass spectrometry and high-performance liquid chromatography were used and confirmed the presence of caffeine, codeine, paracetamol, propyphenazone, pseudoephedrine, dextromethorphan, nordazepam, ramipril and amlodipine in urine sample. Case 2 was positive for tramadol and benzodiazepines. Gas chromatography mass spectrometry was used and confirmed the presence of venlafaxine, its metabolites and nordazepam in serum and urine samples. If a false-positive urine screen result is suspected, nonimmunologic techniques, such as gas chromatography/mass spectrometry or high-performance liquid chromatography, are necessary for confirmation.