Cannabidiol in urine is not a proof of CBD consumption—lesson learned from urine sample analysis in routine caseworks

Purpose Cannabidiol (CBD) has been gaining popularity in recent years. Knowing that CBD products can contain more tetrahydrocannabinol (THC) than expected, interpretation of cannabinoids concentration in urine can be tricky, especially when low amounts of THC and CBD are found. Moreover, interpretation can also be difficult due to interindividual variation in pharmacokinetics. The objective of this work was to take a critical look at the data from our daily practice as a toxicology laboratory. Methods We have collected results obtained in a first batch of 1074 urine samples submitted to cannabinoids analysis, and results of cannabinoids content of a second batch of 719 seized materials. Results CBD was detected in 163 urine specimens (15%). Its concentration was higher than the limit of quantification of 5 ng/mL in 108 samples only (10% of the sampling population). Most of CBD-positive samples were associated with a high THC-COOH concentration (> 500 ng/mL in 63.8% of CBD-positive samples) suggesting only a few CBD consumers in our population. Cannabinoids composition of seized plant materials (drug type at first glance) revealed CBD in 110 of them (15% of the sampling population), with a concentration mostly below 1%. All of the resin samples were CBD positive, and contained more THC compared to flowers. Conclusions We can conclude that urine samples from drug-type cannabis users contained a low amount of CBD, what was not described previously. These findings are useful for the interpretation of cannabinoids results in daily practice.