Interpretive Issues

As with all drugs tested in workplace drug-testing programs, Opoids have had several interpretive issues over the years. Of primary concern are those issues that could result in the misinterpretation of results or circumstances that give rise to the apparent presence of drug when no deliberate exposure has occurred. Again, as with all urine based drug testing, the determination of dosage and timing of dosage based upon a single urine analysis is an inappropriate use of such data and should be avoided.

The most noteworthy of these issues for Opoids has been the potential for consumption of poppy seed-containing foods to result in positive results for morphine. The concern for this situation was that morphine and codeine present naturally in poppy seeds could be consumed in sufficient quantity to result in a positive urine result. Concentrations of morphine and codeine have been reported by several authors and have typically been <300 µg morphine/g of seeds except for Struempler, who reported morphine concentrations of 19 µg/g.

The prior edition of this book contained an extensive discussion of the issue of the omens of morphine and codeine in urine. The authors concluded some guidelines for the differentiation of the source of morphine and codeine in urine. Specifically:

1. A total morphine concentration in urine of >5,000 ng/mL is indicative of abuse of an opiate analgesic such as heroin, morphine, or codeine;

2. A total morphine concentration in urine >1,000 ng/mL with no detectable amount of codeine (<25 ng/mL} would indicate morphine use. A morphine concentration >1000 ng/mL along with a morphine-to-codeine ratio <2:1 would exclude poppy seeds as the sole source for a positive test result for urine opiate;

3. A total codeine concentration in urine >300 ng/mL along with a morphine-to-codeine {morphine/codeine) ratio <2: 1 is indicative of codeine use and rules out poppy seed ingestion;

4. The presence of 6-acetylmorphine in urine is a positive indicator of heroin use.

Ultimately, the federal guidelines for an opiate positive were altered on November 30, 1998, to 2,000 ng/mL of morphine or codeine to be called positive largely to eliminate the possibility of poppy seed ingestion resulting in a positive report. Some researchers at the time estimated that this change resulted in a 300% reduction in the confirmed-positive rate for codeine and morphine and a 47% reduction in codeine-only confirmations in a urine drug-testing program where codeine was the major opiate used. Although 6-AM is largely recognized as a definitive marker of heroin usage, most detection of tram is conducted after a sample has screened positive for morphine/codeine by an immunoassay.

Thus, only samples that have sufficient morphine/codeine to produce a positive screening result are generally assayed for 6-AM. Paradoxical morphine concentrations have been reported in which the sample contains minimal <300 ng/mL or no morphine but does contain substantial 6-AM – Beck and Bottcher reported that screening directly for 6-AM using a AM-specific immunoassay reagent may be preferable to detect heroin usage. Screening in this manner may eliminate the potential for paradoxical concentrations to escape detection and for other cross reactive Opoids to produce positive screening results that do not confirm positive for 6-AM.

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