A urine test for cannabinoids， also known as a urine drug test， is a laboratory test that checks for the presence of tetrahydrocannabinol (THC)， the main psychoactive compound in marijuana. The test can be used to detect marijuana use in the past few days or weeks. It is used for employment screening， driver’s license renewal， and other purposes.

There are two types of urine drug tests:

Immunoassay: This test detects the presence of THC metabolites in urine. It is the most common type of urine drug test. It is fast， easy to use， and relatively inexpensive. However， it may produce false-positive results if the person has eaten or drank before the test.

Gas chromatography-mass spectrometry (GC-MS): This test is more accurate than the immunoassay but is more expensive and takes longer to perform. It can detect the presence of THC and other substances in urine.

If a urine drug test shows the presence of THC， it does not necessarily mean that the person is impaired or addicted to marijuana. It could be because they have eaten or drank something that contains THC， such as poppy seeds or edibles. However， if a person is repeatedly tested positive for THC， it may indicate that they are using marijuana regularly and need help quitting.