Q&A column

Editor: Frederick L. Kiechle, MD, PhD

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Q. If a person died from an overdose, would the toxicology screen always show which drugs were in their system?

A. August 2020—In a drug` intoxication death, toxicology testing typically will detect the drugs in a person’s system. However, there are instances of fatal drug intoxications in which testing does not detect the drug.

Laboratories that are accredited to perform forensic toxicology testing typically test for more than 100 different medications, illicit drugs, and alcohols. Most routine hospital toxicology testing involves a rapid urine screening test for a handful of common drugs or classes of drugs—for example, opiates, cocaine, methamphetamine, and benzodiazepines. These are simple screening tests and do not meet the more rigorous standards for forensic testing, which are broader and require additional definitive testing. In the forensic setting, definitive testing usually involves blood specimens (peripheral sample preferred) as detection in blood may equate to an acute intoxication.

Yet a person could die from a drug intoxication without the testing detecting the drug for numerous reasons. This may occur because the drug is not included in the scope of testing, the drug concentration is below the laboratory’s reporting limit, or there was a prolonged survival interval. Some people may survive for hours or longer in a comatose state following the initial pathological effects of a drug. During this period, the drug continues to metabolize, so it may not be detected in autopsy samples. In such cases, forensic pathologists may attempt to obtain remaining hospital admission blood samples for further testing. Admission specimens retained by the hospital can be a valuable resource for a medical examiner. Postmortem changes, such as decomposition, and the postmortem interval also may affect the concentration of a substance, but most drugs or their metabolites can still be detected.

The recent increase in illicit use of fentanyl, which some hospitals do not include in their urine screen, provides a relevant example. A young person may be admitted to the hospital for a suspected intoxication based on being found with a needle and drug packet. But if fentanyl is not included in the urine screen, the hospital may miss the diagnosis. In such an instance, the medical examiner or coroner may test the blood drawn at admission and detect fentanyl. New fentanyl analogs, such as butyryl fentanyl, are also being used illicitly and may not be detected by a laboratory until new toxicology standards are formulated and implemented.

Cina SJ, Collins KA, Goldberger BA. Toxicology: what is routine for medicolegal death investigation purposes? Acad Forensic Pathol. 2011;1(1):28–31.

Davis GG. National Association of Medical Examiners position paper: recommendations for the investigation, diagnosis, and certification of deaths related to opioid drugs. Acad Forensic Pathol. 2013;3(1):77–83.