UDS: Universal Drug Screen?

Case Scenario: A 29 year-old man with a history of heroin abuse dies in respiratory failure due to a presumed heroin overdose, 6 hours after hospital admission despite resuscitative efforts including administration of multiple doses of naloxone. A UDS test is positive for benzodiazepines and negative for opiates and other illicit drugs of abuse. The death is reported and accepted by the local Medical Examiner (ME). Hospital admission blood and urine samples are additionally requested and conveyed to the ME’s Office. An autopsy is performed along with testing of the hospital admissions samples. The cause of death: Acute intoxication by the combined effects of fentanyl, acetylfentanyl, carfentanil, and alprazolam.

How comprehensive is your hospital lab’s Urine Drug Screen?  A myriad of obscure, clandestinely synthesized, highly potent, harmful, or rapidly fatal drug and medication analogues are not detected by standard urine drug screening tests used in many hospitals. These include fentanyl and fentanyl analogues, synthetic cathinones (“bath salts”), and synthetic marijuana (“K2”, “Spice”). Furthermore, hospital urine drug screening tests are limited by the parameters of the actual testing kit and report the presence (“positive”) or absence (“negative”) of the drug, medication, or drug/medication category included in the panel. Furthermore and for many reasons, a positive result does not always indicate an acute intoxication and a negative result does not exclude one either. Screen tests on blood (i.e. ELISA blood panel) are a better gauge for toxicity but again, only for what is included in the panel. It is important to recognize the limitations of urine drug screening in order to optimize management of the toxidromic patient. Would the patient in the above scenario have benefited from administration of additional doses of naloxone? Consultation with the hospital’s clinical pathologist or medical toxicologist who may recommend sample submission for testing at a more comprehensive reference laboratory, is optimal.

In contrast to hospital testing, postmortem forensic toxicology testing routinely involves comprehensive qualitative and quantitative testing of blood, urine, and other bodily fluids to aid the forensic pathologist in the determination of the cause, contributing factor(s), and the manner of many types of death. In addition to drug deaths, deaths resulting from motor vehicle accidents, falls, fires, over/under-medication, and homicidal and suicidal violence are included, often occurring after a period of hospitalization. In those instances, hospital admission blood and urine samples are particularly advantageous and will be requested if available. Intoxicants found in these samples would indicate a degree of intoxication closer to the actual time of intake and prior to infusion of resuscitative fluids, blood transfusions, metabolism, and the administration of medications. Under these conditions, intoxicants can become undetectable or otherwise uninterpretable due to the presence of low levels of parent drug and/or metabolites. Administration of medicines such as morphine and fentanyl during the terminal hospitalization can further confound interpretation and determination of the cause of death if based on results of testing of postmortem samples only.

 

More on this important topic can be found in Chapters 5 and 6 in Essentials of Death Reporting and Death Certification-Practical Applications for the Clinical Practitioner available on Amazon.com.

 

Stay tuned for your next bolus of Practice Pearls!

 

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