By Laureen Marinetti, PhD, F-ABFT
As part of its whole case approach, Axis Forensic Toxicology includes urine drug testing alongside blood testing in both the Comprehensive Panel with Analyte Assurance™ and Drugs of Abuse Panel. The standard urine screen typically covers common drugs of abuse, excluding barbiturates and cannabinoids—though these can be added upon request.
Urine often contains higher concentrations of drugs and metabolites than blood, and substances may remain detectable in urine for days or longer after use.
From The Society of Forensic Toxicologists (SOFT) Drug-Facilitated Crime Committee. PowerPoint DFSA, DFCC 2017
The primary value of urine drug findings lies in their ability to reveal past drug use. Historical drug use may or may not be relevant to a case. For instance, blood results may show no detectable levels of stimulants such as cocaine or methamphetamine, while urine results are positive—indicating prior use. This information could be significant if the decedent had underlying cardiac disease.
In another scenario, urine results may suggest illicit drug use even when blood results are negative. This can help establish a timeline of drug use or corroborate blood findings. However, the concentration of drugs in urine is generally not useful for determining prior blood levels or the timing of drug use.
Quantitative urine values are only meaningful in specific contexts—such as when extensive comparative data to blood exists (e.g., ethanol), or when distinguishing endogenous from exogenous exposure (e.g., GHB). Axis provides urine concentration data only when it offers interpretive value.
In summary, Axis Forensic Toxicology incorporates urine drug testing alongside blood analysis to provide a more complete picture in forensic investigations. Urine testing is particularly valuable for detecting past drug use, as many substances remain in urine longer and at higher concentrations than in blood. While urine results cannot determine the timing or quantity of drug use, they can offer critical context—especially in cases involving underlying health conditions or suspected substance abuse. Quantitative urine data is only reported when it has clear interpretive value. As always, please do not hesitate to contact Axis Forensic Toxicology with any questions, concerns, or for assistance with case interpretation. Our team is committed to supporting your investigative needs with accurate and insightful toxicological analysis and interpretation.