Urine toxicology screen in multiple sleep latency test: the correlation of positive tetrahydrocannabinol, drug negative patients, and narcolepsy.

Objective: Drugs can influence results of multiple sleep latency tests (MSLT). We sought to identify the effect of marijuana on MSLT results in pediatric patients evaluated for excessive daytime sleepiness (EDS).

Methods: This is a retrospective study of urine drug screens performed the morning before MSLT in 383 patients <21 years old referred for EDS. MSLT results were divided into those with (1) (-) urine drug screens, (2) urine drug screens (+) for tetrahydrocannabinol (THC) alone or THC plus other drugs, and (3) urine drug screens (+) for drugs other than THC. Groups were compared with Fisher exact tests or one-way ANOVA.

Results: 38 (10%) urine drug tests were (+): 14 for THC and 24 for other drugs. Forty-three percent of patients with drug screen (+) for THC had MSLT findings consistent with narcolepsy, 0% consistent with idiopathic hypersomnia, 29% other, and 29% normal. This was statistically different from those with (-) screens (24% narcolepsy, 20% idiopathic hypersomnia, 6% other, 50% normal), and those (+) for drugs other than THC (17% narcolepsy, 33% idiopathic hypersomnia, 4% other, 46% normal (p = 0.01). Six percent (6/93) of patients with MSLT findings consistent with narcolepsy were drug screen (+) for THC; 71% of patients with drug screen (+) for THC had multiple sleep onset REM periods (SOREMS). There were no (+) urine drug screens in patients <13 years old.

Conclusion: Many pediatric patients with (+) urine drug screens for THC met MSLT criteria for narcolepsy or had multiple SOREMs. Drug screening is important in interpreting MSLT findings for children ≥13 years.