Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Opiates are the natural or synthetic drugs that have a morphine-like pharmacological action. Medically, opiates are used primarily for relief of pain. Opiates include morphine and drugs structurally similar to morphine (eg, codeine, hydrocodone, hydromorphone, oxycodone).(1)
Detecting the presence of opiates in the urine
This procedure reports the total urine concentration; this is the sum of the unconjugated and conjugated forms of the parent drug.
Heroin (diacetylmorphine) is rarely detectable in body fluids. It has a half-life of a few minutes. Heroin undergoes rapid deacetylation to 6-monoacetylmorphine (6-MAM), which is about 6 times more potent than morphine. 6-MAM is further deacetylated to morphine; the effects of heroin are attributed to the combined effect of heroin, 6-MAM, and morphine. The presence of 6-MAM is conclusive evidence of prior heroin use. However, due to its short half-life, it is only detectable in urine for about 8 hours after administration.(2)
Codeine is also metabolized to morphine. The presence of morphine in urine can indicate exposure to morphine, heroin, or codeine within 2 to 3 days.(2)
Illicit heroin often contains small amounts of codeine. The presence of both codeine and morphine in urine does not rule out the use of heroin; however, the ratio of morphine to codeine can be helpful in discriminating between heroin and codeine use.(2)
Ingestion of bakery products containing poppy seeds can also cause morphine to be excreted in urine. If excessively large amounts are consumed, this can result in urine morphine concentrations up to 2,000 ng/mL for a period of 6 to 12 hours after ingestion.
The presence of hydrocodone >lower limit of quantitation (LOQ) indicates exposure within 2 to 3 days prior to specimen collection.(2)
The presence of hydromorphone >LOQ indicates exposure within 2 to 3 days prior to specimen collection. Hydromorphone is also a metabolite of hydrocodone, therefore the presence of hydromorphone could also indicate exposure to hydrocodone.(2)
The presence of oxycodone >LOQ indicates exposure to oxycodone within 2 to 3 days prior to specimen collection.(2)
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test detects drugs structurally similar to morphine. Other drugs in the opioid class, such as fentanyl, meperidine, methadone, and opiate antagonists such as naloxone, are not detected.
The presence of meperidine in a very high concentration (overdose proportions) will result in a positive screen report. The gas chromatography/mass spectrometry (GC-MS) report will be negative for opiates.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Positives are reported with a quantitative GC-MS result.
Immunoassay screen: <300 ng/mL
Codeine by GC-MS: <100 ng/mL
Hydrocodone by GC-MS: <100 ng/mL
Hydromorphone by GC-MS: <100 ng/mL
Oxycodone by GC-MS: <100 ng/mL
Morphine by GC-MS: <100 ng/mL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Gutstein HB, Akil H: Chapter 21: Opioid Analgesics. In Goodman and Gilman's The Pharmacological Basis of Therapeutics. Eleventh edition. Edited by LL Brunton, JS Lazo, KL Parker. New York, McGraw-Hill Companies Inc, 2006. Available at: http://www.accessmedicine.com/content.aspx?aID=940653
2. Dispositition of Toxic Drugs and Chemical in Man. Eighth edition. Edited by RC Baselt. Foster City, CA, Biomedical Publications, 2008, pp 355-360, 745-746, 750-752, 1057-1061, 1166-1168