by Kevin Shanks, M.S., D-ABFT-FT
Postmortem redistribution (PMR) is the phenomenon that occurs in blood drug concentrations after death as drug from anatomic sites of high drug concentration (e.g. organs such as the liver, lungs, and heart (myocardium)) is released to sites of lower drug concentration (e.g. the blood). This release may falsely elevate the drug concentration in blood surrounding the organs or from the central cavity.
Substances that are alkaline (pH > 7.0), lipophilic, and have volumes of distribution (Vd) greater than 3 L/kg are more likely to undergo PMR. These substances include many commonly detected drugs such as tricyclic antidepressants (e.g. amitriptyline, nortriptyline), amphetamines (e.g. methamphetamine, amphetamine), and opioids (e.g. fentanyl, oxycodone).
The exact mechanism of PMR has not yet been identified, but changes in pH and protein structure after death are thought to also play a role in the phenomenon. Because of this phenomenon, the preferred anatomical sites of blood collection for toxicological analyses are peripheral sites such as the iliac or femoral veins. The site of blood collection is but one variable in the occurrence of PMR. Other factors influencing PMR include body storage temperature (the higher the temperature, the greater the potential for concentration change), the time between death and specimen collection (a longer lapsed time gives more potential for changes), the position of the body when found (blood may drain from centrally located sites to peripherally located sites), and medical intervention (stomach contents may be aspirated or blood may move from central to peripheral sites; drug may be released from traumatized tissue into blood).
Even as it has been studied for decades, PMR is a complex process and is still not fully understood, but the aforementioned factors are just some variables to be considered when interpreting toxicology’s role in a medical-legal death investigation.
If you have any questions or concerns regarding PMR’s role in a postmortem toxicology case, please reach out to our Axis Forensic Toxicology subject matter experts at email@example.com.
- Barnhart FE, Bonnell HJ, Rossum KM. Postmortem Drug Redistribution. Forensic Sci Rev. 2001. Jul;13(2):101-129.
- Pelissier-Alicot AL, Gaulier JM, Champsaur P, Marquet P. Mechanisms Underlying Postmortem Redistribution of Drugs: A Review. J Anal Toxicol. 2003 Nov-Dec;27(8):533-544.
- Yarema MC, Becker CE. Key Concepts in Postmortem Drug Redistribution. Clin Toxicol (Phila). 2005;43(4):235-241.
- Postmortem Redistribution of Drugs. Principles of Forensic Toxicology. Fifth Edition. Fred S. Apple, Barry S. Levine, Sarah Kerrigan. Springer Nature Switzerland AG. 2020. 595-602.
By Kevin Shanks, M.S., D-ABFT-FT
Toxicology is the study of the effects of substances on living organisms. Forensic toxicology is the use of toxicology in medical-legal investigations. Forensic toxicologists use analytical chemistry, pharmacology, and clinical chemistry to aid in these investigations of death, poisoning, intoxication, or substance use.
The field of forensic toxicology can be broken down into three main realms: postmortem toxicology, human performance toxicology, and forensic drug testing.
Postmortem toxicology is the analysis of biological specimens obtained at autopsy in order to identify the effect of drugs or poisons. These biological specimens may include blood, urine, vitreous humor, bile, gastric contents, and tissues such as liver, kidney, spleen, and brain. The toxicological analyses and toxicologist’s expertise aid in the certification of cause and manner of death, which is determined by the forensic pathologist, medical examiner, or coroner.
Human performance toxicology is the analysis of biological specimens obtained by a hospital or law enforcement agency in order to identify the effects of drugs on psychomotor performance. The typical biological specimen analyzed is whole blood, but may also include blood serum, blood plasma, or in some case, urine. The toxicological analyses and toxicologist’s opinion, in conjunction with observed witness reports and field tests administered by law enforcement officials, help in the determination if a person is under the influence of a substance during a specific incident, such as a motor vehicle stop or collision.
Forensic drug testing is the analysis of biological specimens obtained by a physician, hospital system, the criminal justice system, the public business sector (e.g. Department of Transportation, etc.) and private workplaces or businesses to identify substance use. The primary specimen used in forensic drug testing is urine, but other specimens analyzed include oral fluids, hair, and sweat. The presence or absence of substances detected in biological specimens along with the toxicologist’s scientific opinion, after review of case circumstances and context, allow for the decision to be made regarding potential substance use.
Common instrumentation used across all three realms of forensic toxicology includes immunoassay, gas chromatography with mass spectrometry (GC-MS), and liquid chromatography with mass spectrometry (LC-MS). Routine drugs monitored in all realms include amphetamine, methamphetamine, cocaine, heroin, fentanyl, prescription opioids, PCP, barbiturates, cannabis, and ethanol. The scope of analysis can change to include a more comprehensive scope (e.g. designer opioids, synthetic cannabinoids, novel psychoactive substances, etc.) according to the case circumstances and specifics.
To stay current with the scope of testing for all realms of toxicology offered by Axis Forensic Toxicology, please consult the online test catalog.
- Order Code 70530, Drugs of Abuse Panel, Blood
- Order Code 70510, Comprehensive Drug Panel, Blood
- Order Code 70080, Drugs of Abuse Panel, Urine
- Order Code 13810, Designer Opioids Panel, Blood
- Order Code 42130, Synthetic Cannabinoid Panel, Blood
- Order Code 13610, Psychoactive Substances Panel, Blood
Guidelines for the Interpretation of Analytical Toxicology Results. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages xxx-xlii. (2020).
Introduction to Forensic Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 1-12. (2008).
Postmortem Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 191-218. (2008).
Postmortem Forensic Toxicology. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 3-14. (2017).
Alcohol, Drugs, and Driving. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 299-322. (2008).
Human Performance Toxicology. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 15-30. (2017).
Workplace Drug Testing. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 135-152. (2008).
Forensic Drug Testing. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 31-48. (2017).
Drug Facilitated Sexual Assault. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 287-298. (2008).