The Patient Scenario
A new patient is assessed using several risk evaluation tools (ORT, CAGE-AID) and is considered to be at moderate-to-high risk of substance abuse/misuse. She is already prescribed numerous controlled substances for treatment of chronic pain, depression and anxiety. She denies any use of illicit or recreational drugs.
A lab-based urine immunoassay screen is ordered.
Laboratory-based immunoassay screen
The Test Results
Test results are consistent with her prescribed medications, with the exception of the presence of ∆-9-tetracannabinol (THC).
The Test Interpretation
*Available as unlicensed medicine
The Physician’s Next Step
Having confirmed the presence of THC, the ordering physician must explore the laboratory finding in the context of the clinical setting. In an increasing number of states, the therapeutic value of the cannabinoid molecule, including that obtained from medical marijuana, is now being recognized.
The Final Outcome
At the present time, the appropriate role of medical marijuana is yet to be determined. By convention, where state and federal laws differ, the more stringent law prevails. The case of medical marijuana has become a confusing and muddied exception to this rule. Until this issue is resolved, physicians who recommend or support their patients’ choice to use medical cannabis will continue to place themselves at medicolegal risk.
Cone EJ, et al. Forensic Science International. 2010;198(1):58-61.