Interference with testing for lysergic acid diethylamide
Detlef Ritter, Cherise M Cortese, Linda C Edwards, Judith L Barr, Hyung D Chung, Christopher Long
Clinical Chemistry April 1, 1997 DOI: 10.1093/clinchem/43.4.635
Summary
AI-generated from the abstractA high rate of false-positive LSD results (4.2%) occurred in urine samples from psychiatric patients when using the Emit assay. These positive results could not be confirmed by two different radioimmunoassays or by gas chromatography–mass spectrometry. Adding therapeutic medications commonly prescribed to these patients to normal urine samples produced positive LSD results with the Emit assay, indicating that those drugs interfere specifically with the Emit test for LSD.
Study at a glance
| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 1,898 |
| Population | Psychiatric patients |
| Citations | 24 |
| Key finding | The Emit assay for LSD produces false-positive results due to interference from therapeutic medications taken by psychiatric patients. |
Abstract
Abstract We found a high rate (4.2%) of positive results for lysergic acid diethylamide (LSD) by Emit in 1898 urine samples that were submitted primarily from psychiatric patients for drugs-of-abuse (DOA) testing. Specimens that tested positive for LSD by Emit subsequently tested negative for LSD with two RIAs. Furthermore, LSD was not detected in randomly selected Emit-positive urine samples by gas chromatography–mass spectrometry. Normal urine samples tested positive for LSD by Emit when they were supplemented with therapeutic medications that were prescribed for patients with positive urine LSD results by Emit. These therapeutic drugs interfered specifically with the Emit assay for LSD, since other Emit DOA tests were not affected by these medications at the tested concentrations.