Federal guidelines for marijuana screening should have lower cutoff levels. A comparison of results from immunoassays and gas chromatography-mass spectrometry.
Federal guidelines for urine marijuana testing use a screening cutoff of 100 ng/mL and a confirming cutoff of 15 ng/mL. We tested 75 urine samples with two different immunoassays with cutoff points of 100 and 20 ng/mL. The same samples were also analyzed with gas chromatography-mass spectrometry. At the government recommended cutoff levels for screening and confirming, test sensitivity was 47% and specificity was 91%. With a screening cutoff of 20 ng/mL confirmed at 5 ng/mL, test sensitivity was 88% and specificity was 94%. We suggest adoption of these lower cutoff levels.
Smith
D E
DE
Department of Pediatrics, University of Virginia Health Sciences Center, Charlottesville.
Gutgesell
M E
ME
Schwartz
R H
RH
Thorne
M M
MM
Bogema
S
S
D002849:Chromatography, Gas; D013759:Dronabinol / Q000652:urine*; D006801:Humans; D007124:Immunoenzyme Techniques; D008385:Marijuana Smoking / Q000453:epidemiology / Q000652:urine*; D013058:Mass Spectrometry; D011237:Predictive Value of Tests; D012016:Reference Values; D015813:Substance Abuse Detection / Q000331:legislation & jurisprudence / Q000592:standards*; D014481:United States
D013759:Dronabinol