Morphine is an opioid analgesic used in treatment of moderate to severe pain unresponsive to routine pain medication. Urinalysis of morphine is usually done to detect heroin abus It is done to detect morphine toxicity in patients. The morphine-positive urinalysis cutoff value is 2000 ng/ml.
Opioids are drugs derived from opium which is an extract of poppy seeds and include morphine, codeine and heroin. Morphine is a potent drug routinely used as an analgesic in the treatment of moderate to severe pain which does not respond to other pain killer medications. Heroin is an illicit drug which is used as a substance of abuse leading to drug addiction. Codeine is used as a component in cough syrups. Codeine and heroin also get metabolized to morphine in the body. Opioids like morphine and codeine when used in therapeutic doses under the supervision of a medical practitioner and in specific conditions produce minimal side effects. Levels above the prescribed therapeutic doses can lead to drug toxicity.
Morphine when exceeds therapeutic doses can cause central nervous system depression leading to dizziness, drowsiness, apathy and lethargy. At higher doses, it also causes pinpoint pupils, warm and flushed skin and respiratory depression. Knowledge of the morphine positive urinalysis cutoff value helps one in diagnosing such a condition and taking appropriate remedial measures.
Drug Testing for Morphine
Indications for morphine testing:
- If morphine or heroin abuse is suspected.
- As a routine test in case of patients on long term morphine for pain to detect over-dosage and prevent adverse effects.
Morphine and other opioids can be detected in urine upto 24 hours or for several days depending upon the agent and amount administered. Immunoassay techniques are used to detect morphine which is excreted as glucuronide conjugates. But codeine, dihydrocodeine and hydromorphine also cross react with morphine and may show positive results. Morphine and codeine are present in small quantities in poppy seeds and thus they can detected in urine upto 48 hours at a cut off value of 300 ng/ml. Thus if the test is positive, specific chromatographic tests should be done to detect specific opioids. Additional testing is required to differentiate heroin abuse from poppy seed ingestion.
Procedure
A random urine sample of 50-60 ml is collected in a plastic urine container and refrigerated.
The primary screening tests for morphine are:
- Immunoassay
- Thin layer chromatography
- High performance liquid chromatography
If this gives a positive morphine urinalysis then the confirmatory tests should be done:
- Gas chromatography
- Mass spectrometry
- Detection of 6-monoacetylmorphine in urine to confirm heroin abuse
The confirmatory morphine positive urinalysis cutoff value is 2000 ng/ml. If the level of morphine is more than 2000 ng/ml, then testing for acetylmorphine is also necessary as a confirmatory test, whose cut off value is 10 ng/ml.
Conclusion
Laboratory testing when used in an appropriate clinical setting can help in accurate diagnosis to detect substance abuse. But it has its own limitations. The urine test for morphine can detect substance abuse within a few preceding days, but it cannot confirm drug dependence. Thus clinical examination and history coupled with sensitive and specific tests for morphine detection in urine can help in diagnosis of substance abuse or detect drug toxicity.
References
- Drug Abuse Handbook 2nd ed. by Steven B. Karch
- Principles of Addiction Medicine, 4th ed. by By Richard K Ries, Shannon Miller, David A Fiellin, Richard Saitz
- The Immunoassay Handbook 3rd ed. by David Wild
- Poisoning and Toxicology Handbook 4th ed. by By Jerrold B. Leikin, Frank P. Paloucek
