Reports of the Match 180 seconds from the French-speaking Days of Medical Biology

Urine drug screening is carried out on numerous automated analysis platforms using enzyme-linked immunosorbent assays. While these methods are rapid, they often lack specificity. We report the case of a 5-year-old child treated for Dravet syndrome and hospitalized for clonic seizures. During her hospitalization, three urine samples were sent to the toxicology laboratory to rule out any toxic origin for these seizures. The first two were positive for ecstasy, and negative for other drugs. For the last sample, all tests were negative. The presence of ecstasy in the first two samples was not confirmed by gas chromatography-mass spectrometry, which identified stiripentol in all three urines. Stiripentol is an antiepileptic drug that shares a 3,4-methylenedioxy group with MDMA. We determined that the antibody in the kit crossed 20% with stiripentol, and were able to define a stiripentol cut-off concentration of 2,500 ng/mL. We checked this cut-off by measuring stiripentol in the three urine samples, finding concentrations of 47,600 and 5,800 ng/mL for the first and second samples respectively, and 1,900 ng/mL for the last one. These concentrations explain the false positives in the first two urine samples, and the negative result in the last one. This work underlines the need to remain critical of the results of immuno-screening methods, and to confirm them with a reference method.