Unresolved discrepancies between cannabinoid test results for infant urine

Area of Science:

• Clinical Chemistry
• Toxicology
• Pediatrics

Background:

• False-positive results in drug screening for tetrahydrocannabinol (THC) have been noted.
• Investigated discrepancies in unconfirmed positive THC screen results between infant and non-infant urine samples.

Purpose of the Study:

• To determine the rate of unconfirmed positive THC screen results in infant versus non-infant urine samples.
• To explore potential reasons for observed differences, including infant-specific urine constituents.
• To develop and assess a method for detecting a THC metabolite in infant urine.

Main Methods:

• Retrospective analysis of two large datasets (reference and hospital laboratories) comparing immunoassay drug screens with confirmation tests.
• Assessment of positive THC screens based on the likelihood of cannabinoid presence in samples.
• Development of a method to detect 11-hydroxy-Δ⁹-THC in infant urine.

Main Results:

• Unconfirmed positive THC screens were significantly higher in infants (47%) compared to non-infants (0.8%).
• Infant samples with a high likelihood of cannabinoid presence showed a 50% unconfirmed positive rate, while those with low likelihood screened negative.
• The THC metabolite 11-hydroxy-Δ⁹-THC was not detected in any tested infant urine samples.

Conclusions:

• Standard confirmatory methods for THC may be unsuitable for infant urine samples.
• The study suggests unrecognized THC-associated compounds, rather than infant-specific interference, are responsible for false-positive THC screens in infants.