Page "Morphine" Paragraph 43

Morphine and its major metabolites, morphine-3-glucuronide and morphine-6-glucuronide, may be quantitated in blood, plasma, or urine to monitor for abuse, confirm a diagnosis of poisoning or assist in a medicolegal death investigation.

Most commercial opiate screening tests based on immunoassays cross-react appreciably with these metabolites.

However, chromatographic techniques can easily distinguish and measure each of these substances.

When interpreting the results of a test, it is important to consider the morphine usage history of the individual, since a chronic user can develop tolerance to doses that would incapacitate an opiate-naive individual, and the chronic user often has high baseline values of these metabolites in his system.

Furthermore, some testing procedures employ a hydrolysis step prior to quantitation that converts the metabolic products to morphine, yielding a result that may be many times larger than with a method that examines each product individually.

Interpretation can be confounded by usage of codeine or ingestion of poppy seed foods, either of which leads to the presence of morphine and its conjugated metabolites in a person's biofluids.