From the Research
Investigations for marijuana intoxication should include a combination of clinical assessment and laboratory testing, with a focus on urine drug screening, blood testing, and saliva testing to detect THC metabolites and active THC levels, as supported by the most recent study 1. When evaluating a patient for marijuana intoxication, a thorough history and physical examination are essential, focusing on vital signs, mental status, and symptoms like tachycardia, conjunctival injection, dry mouth, increased appetite, and impaired coordination.
- Urine drug screening is the most common laboratory test, detecting THC metabolites for days to weeks after use, though this indicates recent use rather than current impairment.
- Blood testing provides more accurate information about acute intoxication, measuring active THC levels which correlate better with impairment, as shown in the study 1.
- Saliva testing can detect recent use (within 24-48 hours) and is increasingly used in roadside testing. In severe cases with complications, additional tests may include:
- Complete blood count
- Electrolytes
- Blood glucose
- Cardiac enzymes Neuroimaging is rarely needed unless there are concerns about other conditions causing altered mental status. These investigations help differentiate marijuana intoxication from other medical conditions with similar presentations and guide appropriate management, particularly in emergency settings or when assessing fitness to drive or work, as discussed in the study 2. The study 3 also highlights the importance of analyzing THC-COOH to creatinine ratios in urine samples to differentiate between recent drug use and residual THC-COOH excretion. However, the most recent study 1 provides the most accurate and up-to-date information on the diagnostic investigations for marijuana intoxication.