Cannabinoids (TCH)

CPT Code:  80101 
Specimen:  Urine 
Volume:  30 mL 
Container:  Use plastic urine drug bottle and evidence tape or tamper-evident container for forensic specimen. Collection kits are available by request from the laboratory. 
Collection: 

Urine specimens should be collected in clean, unbreakable, and leak proof containers.  Freshly voided urine specimens should be used.

Fresh urine specimens do not require any special pretreatment.  No additives or preservatives are required.  Boric acid should not be used as a preservative.

Specimens may be encountered that display turbidity.  It is recommended that such specimens be centrifuged before analysis.

Specimens should be within the pH range of 5-8.  Specimens with a pH outside this range should be adjusted to this range by the addition of 1N HCl or 1N NaOH before analysis.

Specimens should be at a temperature of 20-25 ⁰C before analysis.

Stability:  If not analyzed immediately, specimens should be stored refrigerated for less than 24 hours.  Specimens should be frozen if storage longer than 24 hours is required. 
Cutoff: 

50 ng/mL

Note: This method provides only a preliminary analytical test result.  A more specific alternate chemical method must be used in order to obtain a confirmed analytical result.  Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method.  Other chemical confirmation methods are available.  Clinical consideration and professional judgment should be applied to any drug of abuse test result, particularly when preliminary positive results are used.

Use:   Measurements obtained with THC method are used in the diagnosis and treatment of cannabinoids use or overdose.
Information: 

Marijuana is a mixture of dried leaves and flowering tops of the plant Cannabis sativa L.  The agents that produce the hallucinogenic and other biological effects of marijuana are called cannabinoids.  The immediate effects of smoking marijuana include a faster heartbeat and pulse rate, bloodshot eyes, and a dry mouth and throat. The drug can impair or reduce short-term memory, alter sense of time, and reduce the ability to do things that require concentration, swift reactions and coordination, such as driving and operating machinery.

The cannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) is the principal psychoactive ingredient in marijuana and hashish.  The compound Δ9-THC is quickly and effectively absorbed by inhalation or from the gastrointestinal tract, and is almost completely metabolized by liver enzymes.  Peak plasma levels of Δ9-THC occur within 10 minutes of inhalation and approximately 1 hour after ingestion.  Approximately 30% of a dose of THC is excreted as urinary metabolites within 72 hours after exposure.  Concentration depends on the total amount of THC absorbed, frequency of abuse, rate of release from fatty tissue, and time of specimen collection with respect to use.  In chronic users, THC may accumulate in fatty tissue faster than it can be eliminated.  This accumulation leads to longer detection times in urinalysis for chronic users than for occasional users.

Methodology: 

 EMIT®