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Interference with testing for lysergic acid diethylamide
D Ritter1, C M Cortese, L C Edwards
1Pathology and Laboratory Medicine, John Cochran Veterans Affairs Medical Center, Saint Louis, MO 63106, USA. ritterdg@sluvca.slu.edu
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.
Insights
A common drug test for lysergic acid diethylamide (LSD) showed high false positive rates. Therapeutic medications interfered with the Emit assay, leading to inaccurate lysergic acid diethylamide (LSD) drug testing results.
Area of Science:
- Forensic Toxicology
- Analytical Chemistry
- Clinical Chemistry
Background:
- The Emit assay is widely used for drugs-of-abuse (DOA) screening.
- Accurate detection of lysergic acid diethylamide (LSD) is crucial in clinical and forensic settings.
- Potential interferences in DOA testing can compromise patient care and legal outcomes.
Purpose of the Study:
- To investigate a high rate of positive results for lysergic acid diethylamide (LSD) using the Emit assay.
- To identify the cause of false positive results in lysergic acid diethylamide (LSD) drug testing.
- To assess the impact of therapeutic medications on Emit DOA assays.
Main Methods:
- Analysis of 1898 urine samples using the Emit assay for lysergic acid diethylamide (LSD).
- Confirmation of Emit-positive samples using two different radioimmunoassay (RIA) methods.
- Gas chromatography-mass spectrometry (GC-MS) analysis of selected Emit-positive samples.
- In vitro testing of urine samples supplemented with common therapeutic medications.
Main Results:
- A high prevalence (4.2%) of false positive lysergic acid diethylamide (LSD) results was observed with the Emit assay.
- Emit-positive samples consistently tested negative for lysergic acid diethylamide (LSD) by RIA and GC-MS.
- Therapeutic medications commonly prescribed to psychiatric patients caused false positive lysergic acid diethylamide (LSD) results in the Emit assay.
- Other Emit DOA tests were not affected by the tested therapeutic medications.
Conclusions:
- The Emit assay demonstrates poor specificity for lysergic acid diethylamide (LSD) detection in urine.
- Therapeutic drug interference is a significant issue with the Emit assay for lysergic acid diethylamide (LSD).
- Clinical laboratories should be aware of potential false positives and consider confirmatory testing for lysergic acid diethylamide (LSD).
