SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

C2
PARADOXICAL RESULTS FROM SCREENING FOR URINARY 6-AM AND OPIATES WITH
DIFFERENT IMMUNOASSA YS IN A HEROIN SUBSTITUTION TREATMENT POPULATION
OlofBeck and Michael Boettcher*
Department of Medicine, Division of Clinical Phannacology, Karolinska University Hospital, Stockholm,
Sweden. * Arztpraxis rur Medizinische Mikrobiologie, Labordiagnostik und Hygiene, Dessau, Gennany
Identification of 6-Acetylmorphine (6-AM) in urine samples is regarded as an unequivocal proof of recent
heroin abuse. Due to its short elimination half-life of about 30min, 6-AM normally cannot be detected for a
longer period than 24 hours after heroin consumption. In addition, it is generally assumed that the
metabolite morphine and its glucuronidated fonns can be detected much longer. Therefore, the presence of
6-AM in urine samples at detectable levels is only expected together with high total morphine
concentrations.
Since the availability of the 6-AM CEDIA (Microgenics) we started to test opiate-CEDIA (Microgenics)
positive samples with the 6-AM assay before GCIMS analysis for 6-AM is conducted. This is done
semiquantitatively on a Hitachi 911 with calibrators at 0, 5, 10 and 20nglmL applying a cutoff at 5nglmL.
Quantitative results within the measuring range of the 6-AM CEDIA mostly correlate well with the data of
GCIMS but are discrepant when increased amounts of free morphine are present in the sample. This crossreactivity
of free morphine (~0.06%) can even lead to false positive results especially for samples from
patients substituted with morphine.
As we always screen urine samples from dihydocodeine substituted patients with the 6-AM CEDIA instead
of opiate-CEDIA we wanted to learn if there are any other cross-reactive drugs increasing the 6-AM
CEDIA result or can lead to false positives. We therefore run the 6-AM test together with the opiate­
CEDIA and opiate-DRI (Microgenics) on every urine sample from substituted patients on 49 consecutive
workdays (3696 samples). No false positive results were found with the 6-AM assay. However, in 29
(0.8%) samples from 23 different patients (9 females, 14 males) paradoxical results were observed with
positive 6-AM CEDIA results (>5ng/mL) and negative (cutoff 100nglmL) or low positive results
«400ng/mL) in the opiate tests. The DRI and CEDIA opiate immunoassays gave similar results.
Interestingly all the samples analysed were confinned to be 6-AM positive with only small or undetectable
amounts of free morphine. There were only two discrepant samples where the concentration of 6-AM
found with GCIMS (9.3ng/mL, 2.5ng/rnL) was significantly lower than expected from the 6-AM CEDIA
assay (both samples >20ng/mL). An additional cross-reactive substance or perhaps cross-reacting 6-AM-3­
glucuronide may be assumed. Ongoing investigations with LC-MS-MS will look for 6-AM-3-glucuronide
and morphine-3- and morphine-6-glucuronide in all 29 samples.
Conclusion: Positive screening results for urinary 6-AM as a proof for very recent heroin abuse should be
looked at very carefully and always in the context oftotal morphine concentration.
Keywords: 6-AM, opiates, CEDIA
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