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False-positive LSD testing in urine samples from intensive care patients
J Röhrich1, S Zörntlein, J Lotz
1Institute of Legal Medicine, Johannes Gutenberg-University Mainz, Germany.
Journal of Analytical Toxicology
|September 16, 1998
Summary
A common drug, ambroxol, can cause false positive results for lysergic acid diethylamide (LSD) in urine tests. This cross-reactivity in the CEDIA DAU assay requires careful interpretation of positive LSD findings, especially during cold season.
Area of Science:
- Clinical Chemistry
- Forensic Toxicology
- Pharmacology
Background:
- Routine drug screening in intensive care units (ICUs) is crucial for patient management.
- Unexpected positive results for lysergic acid diethylamide (LSD) were observed during standard urine testing.
Purpose of the Study:
- To investigate the cause of false positive lysergic acid diethylamide (LSD) results in urine samples.
- To identify potential interfering substances in drug screening assays.
Main Methods:
- Urine samples from 12 ICU patients with positive lysergic acid diethylamide (LSD) immunoassay results were analyzed.
- High-performance liquid chromatography (HPLC) was used for confirmation.
- Cross-reactivity studies were performed with ambroxol in the CEDIA DAU LSD assay.
Main Results:
- None of the positive lysergic acid diethylamide (LSD) results could be confirmed by high-performance liquid chromatography (HPLC).
- All tested samples contained ambroxol, a common mucolytic drug.
- Ambroxol demonstrated significant cross-reactivity in the CEDIA DAU lysergic acid diethylamide (LSD) assay.
Conclusions:
- The CEDIA DAU lysergic acid diethylamide (LSD) assay can produce false positive results due to ambroxol.
- Positive lysergic acid diethylamide (LSD) findings from this assay require critical evaluation, particularly when patients use mucolytic medications.
- Increased use of mucolytics during respiratory infections may lead to more frequent false positives.