{"id":50292,"date":"2020-07-05T20:31:16","date_gmt":"2020-07-05T20:31:16","guid":{"rendered":"https:\/\/www.nationaldrugscreening.com\/?post_type=faqs&#038;p=50292"},"modified":"2020-07-05T20:31:33","modified_gmt":"2020-07-05T20:31:33","slug":"can-you-please-explain-why-confirmation-cutoff-levels-are-lower-than-screening-levels","status":"publish","type":"faqs","link":"https:\/\/www.nationaldrugscreening.com\/faqs\/employer-drug-testing\/can-you-please-explain-why-confirmation-cutoff-levels-are-lower-than-screening-levels\/","title":{"rendered":"Can you please explain why confirmation cutoff levels are lower than screening levels?"},"content":{"rendered":"\n<p>For drug screening tests, a cut-off is chosen that will optimize drug detection but minimize the number of false positive results. It is important to note that a negative sample doesn\u2019t mean that it is drug free; it might contain a drug at a concentration that is lower than the defined cut-off.&nbsp;<\/p>\n\n\n\n<p>Screening and confirmation testing are performed using different methodologies that necessitate different cutoff levels. The cutoff levels of an immunoassay screen are typically higher than those of a more sensitive GC\/MS or LC\/MS\/MS confirm test, because they screen for a larger group of parent compounds, metabolites and other structurally similar compounds.&nbsp;<\/p>\n\n\n\n<p>If a screening test detects a drug (above the screening cutoff level) the presumptive positive specimen will be sent to GC\/MS or LC\/MS\/MS confirmation testing. Many times, these individual compounds are present in concentrations much lower than the total immunoassay response, thus resulting for the cutoff levels being lower for the GC\/MS or LC\/MS\/MS test.&nbsp;<\/p>\n\n\n\n<p>The screening test is very general and the confirmation test is very specific.&nbsp;<\/p>\n\n\n\n<p><strong>A specific example:<\/strong><\/p>\n\n\n\n<p>The cut off for marijuana on the screen is 50 ng\/ml, which is a composite of all 31 metabolite concentrations. If the sample is below this level the test is over as a passing status. If the sample is over 50 ng\/ml the sample is sent on to a GC\/MS for confirmation. The cutoff for the confirmation is lower at 15 ng\/ml because the machine only identifies one of the 31 metabolites which is the 11-nor-D-9-tetrahyrocanibinolic acid. To pass, the one metabolite must be below the 15-ng\/ml cutoff.<\/p>\n","protected":false},"author":1,"template":"","acf":[],"_links":{"self":[{"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/faqs\/50292"}],"collection":[{"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/faqs"}],"about":[{"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/types\/faqs"}],"author":[{"embeddable":true,"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":0,"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/faqs\/50292\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.nationaldrugscreening.com\/wp-json\/wp\/v2\/media?parent=50292"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}