Cannabis and urine samples.
For what duration may cannabinoids be detected in urine after cessation of cannabis use Medical literature has been reviewed to shed light on the most important issues regarding excretion and detection of cannabinoids, and how to correctly interpret the findings. The article is based on the authors experience with interpreting urine drug screening results and on a non-systematic search for relevant literature on pharmacokinetics and urinary excretion of cannabinoids. Cannabis users are usually identified through detection of 11-nor-9-corboxy-Delta9-tetrahydrocannabinol (THCCOOH) in urine. Depending on the extent of use, THCCOOH may be detectable in urine from a few days up to three months after cessation of cannabis use. To correctly differentiate between new intake and residual drug excretion, the urinary THCCOOH concentrations must be measured quantitatively and the interpretation must take into account urine dilution and the time span between the dates of specimen collection. Information about the extent of cannabis use and the potential sanctions involved, may influence on how results are interpreted. Differentiating new cannabis intake from residual excretion can be difficult in chronic users. The most precise interpretations are achieved through an open dialogue between client, clinician and laboratory.