The major active component of marijuana is Tetrahydrocannabinol (THC). Marijuana drug testing detects the presence of THC and its metabolites in the given sample. The detection of drug can be based on certain factors such as amount smoked, individual body metabolism rates, and other health related issues of a person. After consumption of THC it is sent throughout the body through blood. It gets converted into 9-carboxy-11-nor-delta-9-THC which is the predominant metabolite. The metabolite is present in plasma, faeces, urine, along with other compounds.

Marijuana drug test through urine, only detects the metabolites and byproducts of the drug. The drug can be present in a person’s body up to 40 days if he is a frequent user. Among people who consume the drug rarely, the drug can be detected from two to ten days. THC and its metabolites are stored in fat tissues in the body. As it is a fat soluble compound it enters the urine slowly. So urine test detects the drug that has been consumed a long time before.

The initial cut-off level for drug detection is 50ng/ml. When once the concentration is found above this level the person is tested as positive. However, for further confirmation, the sample is sent for further laboratory tests. Gas Chromatography-Mass Spectrometry tests are conducted and the cut-off level was set for 15ng/ml. Then the person is officially tested as positive.

Sometimes detection of THC and its metabolites in urine can be done for months after its use. However, for chronic users, more realistic estimate is 3-4 weeks. Apart from urine testing, marijuana testing can be done by hair, blood, and saliva samples. However, urine test is the most common tests performed at many places.