تسجيل الدخول

تسجيل

Interpretation of opiate positive results

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  148

2026-10-03

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Interpretation of opiate positive results

This is another area that has caused confusion in the MRO community. From 1989 to 1998 the cut-off used for the opiates was 300 ng/mL, both in the initial testing and in the confirmation of codeine and morphine by GC-MS. During this period there was no requirement that a certified laboratory should be able to confirm the presence of the characteristic metabolite of diamorphine, MAM, although several did so routinely. In 1998 the cut-offs were raised to 2000 ng/mL and the laboratories were required to confirm the presence of MAM if the morphine concentration exceeded 2000 ng/mL. The GC-MS cut off for MAM was set at 10 ng/mL. The major reason for raising the opiate cut-offs was associated with MRO reviews of opiate-positive samples. Use of the 300 ng/mL cut-off criterion resulted in a large number of positive results that derived from either poppy-seed ingestion or therapeutic doses of codeine, and which were subsequently verified as negative by the MROs. Where there was a prescription for codeine, the MRO’s review presented no problems. However, in the absence of a prescription for codeine (or morphine) the MRO was required to observe ‘clinical signs of opiate use’ before reporting a verified opiate-positive result back to the employer. This requirement remains for some results, even within the new CFR Part 40, unless the specimen has tested positive for MAM, which is conclusive evidence of diamorphine use. Under the new CFR Part 40, if the morphine concentration is greater than 15 000 ng/mL the donor has the responsibility for providing evidence that the presence of morphine was the result of a legitimate use of a drug, and not the illicit use of diamorphine or morphine. There are certainly no reports that indicate such urinary morphine concentrations from poppy-seed ingestion, even under extreme conditions (Selavka 1991), so if the donor cannot provide this evidence the MRO verifies the result as a positive.