Cannabinoid Substance Concentration (Serum/Plasma)
This test measures the amount of cannabinoids, such as THC (tetrahydrocannabinol) or its metabolites, in your blood or plasma. It helps assess recent or past cannabis use.
["This test checks for active or recent cannabis exposure in your bloodstream."]
Key facts at a glance
- LOINC
- 16543-1
- Short code
- CANNCFM
- Synonyms
- Cannabinoids Usub Cfm-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top vacutainer tube (no anticoagulant) for serum collection; alternatives include serum separator tubes (SST). Chain of custody containers may be required for forensic samples.
- Units
- N/A
- Ref low
- 0
- Ref high
- 10
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- confirm
- CPT
- 80349
- SNOMED
- 167997009
- Specimen volume
- 5-10 mL of whole blood yielding approximately 2-4 mL of serum
- Stability
- Serum stable at room temperature for 24 hours; refrigerated at 2-8°C for 7 days; frozen at -20°C for longer storage up to 6 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–96 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have concerns about recent cannabis use, such as after a traffic stop, workplace screening, or if you’re suspected of impairment. It can also be used in medical or legal contexts to evaluate substance exposure.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for a few hours if blood is drawn. Avoid smoking or consuming cannabis products for at least 24 hours before testing if possible.
What the Test Results Mean
Results show the concentration of cannabinoids in your blood or plasma. Higher levels may indicate recent cannabis use, while lower levels suggest less recent exposure. Interpretation depends on clinical context (e.g., time since last use, reason for testing).
Common Uses and Limitations
This test is primarily used for screening or confirmation of cannabis use, especially in legal or workplace settings. It may not detect long-term storage of cannabinoids in the body, as metabolites can clear quickly.
Reference range
Negative (cutoff varies by laboratory; typically <10 ng/mL for THC-COOH). Report includes detected cannabinoid analytes with quantitative concentrations.N/A
No fasting required. Patient should be informed that this is a confirmatory test typically performed after a positive screening result. Chain of custody procedures may apply for forensic or workplace testing scenarios.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Cannabinoid Level
Frequently asked questions
How long does it take to get results from this test?
Can I drink alcohol before this test?
Will this test show if I’ve used cannabis long-term?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy