When cannabis is consumed, the body processes its active compounds, primarily delta-9-tetrahydrocannabinol (THC), through metabolic steps. These transformations result in various byproducts, which the body breaks down for elimination. Understanding these transformed compounds, particularly Carboxy-THC, provides insight into how cannabis use is detected.
What is Carboxy-THC
Carboxy-THC, scientifically known as THC-COOH, is a significant metabolite of THC. It is a non-psychoactive compound, meaning it does not produce the “high” associated with cannabis use.
Carboxy-THC functions as an inactive breakdown product of THC. Its presence indicates that THC has been processed and is being eliminated. Unlike THC, Carboxy-THC does not bind to cannabinoid receptors in the brain to elicit intoxicating effects.
How Carboxy-THC Forms in the Body
The formation of Carboxy-THC begins when THC enters the body, undergoing metabolism in the liver. Liver enzymes play a central role in this conversion process.
THC is initially converted into an intermediate metabolite called 11-hydroxy-THC (11-OH-THC). This compound is also psychoactive. Subsequently, 11-OH-THC is further oxidized by liver enzymes into the non-psychoactive Carboxy-THC. Once formed, Carboxy-THC is often conjugated with glucuronide, making it more water-soluble and easier for the body to excrete.
Why Carboxy-THC Matters for Testing
Carboxy-THC is the primary target for cannabis drug screenings due to characteristics that make it a reliable indicator of past use. Its non-psychoactive nature means its detection confirms previous cannabis exposure rather than current impairment. This distinction is important for legal and workplace contexts.
The stability of Carboxy-THC and its longer detection window compared to active THC are also key factors. As a lipid-soluble compound, Carboxy-THC is stored in fat cells and gradually released. This allows it to remain detectable for days, weeks, or even months, depending on individual factors and frequency of use, making it an effective biomarker for cannabis consumption.
Methods for Detecting Carboxy-THC
Various methods are employed to detect Carboxy-THC, each offering different detection windows.
Urine Tests
Urine tests are common and can detect Carboxy-THC for an extended period, ranging from a few days for single use to several weeks or even months for chronic users. These tests typically use immunoassay for initial screening, followed by more precise methods for confirmation.
Hair Follicle Tests
Hair follicle tests provide a longer detection window, typically covering up to 90 days of cannabis use. They detect Carboxy-THC and other metabolites incorporated into the hair shaft. While effective for identifying long-term use, hair tests can sometimes be affected by external contamination.
Blood Tests
Blood tests can detect Carboxy-THC, with detection windows generally ranging from a few days to a few weeks. These tests can also differentiate between active THC and its metabolites, providing insights into recent consumption versus past use.
Oral Fluid Tests
Oral fluid tests are primarily used to detect more recent cannabis use. While Carboxy-THC can be detected, active THC usually predominates, and its presence helps differentiate true consumption from passive exposure.