In a forensic toxicology case, a urine sample is found to contain morphine and codeine. This finding can indicate which of the following scenarios?

• A Heroin (diacetylmorphine) use only, as heroin metabolises to both morphine and codeine
• B Codeine use only, since codeine cannot be produced from morphine
• C Morphine injection directly, as morphine cannot yield codeine as a metabolite
• D Either heroin use (morphine + 6-MAM) or natural opium/codeine exposure, as codeine is independently found in poppy-derived products and metabolises to morphine ✓

Explanation

Codeine and morphine both occur naturally in opium and can appear together in urine from multiple sources: (1) heroin metabolises to 6-monoacetylmorphine (6-MAM, specific heroin marker) then to morphine; codeine in heroin preparations appears as an impurity; (2) codeine is itself an O-demethylated to morphine via CYP2D6. The specific marker for heroin use is 6-MAM, not just morphine/codeine co-presence. Without 6-MAM, the finding of morphine plus codeine is non-specific and cannot distinguish heroin use from natural opium, oral codeine, or poppy seed ingestion.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.