For the Week of March 20, 2017

What is the difference between a presumptive lab test and a definitive lab test?

Presumptive tests are used to identify possible use or non-use of a drug or drug class (i.e., the presence or absence of a drug in a urine sample). Qualitative or quantitative methods that identify possible drug use or non-use and identify the specific drugs and associated metabolites are definitive tests.