Cutoff levels for drugs and drug metabolites.

CFR · 2024-01-01 · US · Title 10

(a) (2) HHS-certified laboratories shall conduct special analyses of specimens as follows: (i) If initial validity testing indicates that a specimen is dilute, or if a specimen is collected under direct observation for any of the conditions specified in § 26.115(a)(1) through (3) or (a)(5), the laboratory shall compare the immunoassay responses of the specimen to the cutoff calibrator in each drug class tested; (ii) If any immunoassay response is equal to or greater than 40 percent of the cutoff calibrator, the laboratory shall conduct confirmatory drug testing of the specimen to the LOQ for those drugs and/or drug metabolites; and (iii) The laboratory shall report the numerical values obtained from this special analysis to the MRO. (b) (2) Each confirmatory drug test must provide a quantitative result. When the concentration of a drug or metabolite exceeds the linear range of the standard curve, the laboratory may record the result as “exceeds the linear range of the test” or as “equal to or greater than <insert the value for the upper limit of the linear range>,” or may dilute an aliquot of the specimen to obtain an accurate quantitative result when the concentration is above the upper limit of the linear range.

official document · source cfr-2024 · id 10:§ 26.163