Definition - What does immunoassay screening test mean?
An immunoassay screening test is an initial drug screen that is cheaper for mass screening of large numbers of employees than lab verified testing of every employee. This screening test looks for an immune system response to chemicals in the sample (generally urine) as an indicator of drug use. Many instant drug tests use immunoassay methods but immunoassay testing can also be done in a lab using a immunoassay analyzer machine.
SureHire explains immunoassay screening test
An immunoassay screening test is an initial drug screen that uses the body's response to introduced drugs, rather than the drug itself in a sample (urine). These tests can return results nearly instantly or take more time depending on the specific version of the test. They can also be done on site by trained employees (or outside contractors) or in a lab with a immunoassay analyzer machine. While cheaper than other testing methods and generally faster, immunoassay screening tests do occasionally return false positives so a confirmatory test should be conducted on any positive results. Gas chromatography mass spectrometry (GC/MS) is generally used in this confirmation lab testing.