Cannabinoid Hair Mass Concentration (24-hour)
This test measures the amount of cannabinoids (active compounds from cannabis) in a hair sample over a 24-hour period. It helps assess recent or long-term exposure to cannabis.
["This test can reveal past cannabis use, even if you’ve stopped recently."]
Key facts at a glance
- LOINC
- 59160-2
- Short code
- CANHAIR
- Synonyms
- Cannabinoids Hair-mCnt
- Category
- chemistry
- Sample
- serum
- Container
- Foil-wrapped hair specimen envelope or sterile specimen container; chain-of-custody container if forensic/legal specimen
- Units
- N/A
- Ref low
- 0
- Ref high
- 0.1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 1–99 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Gas Chromatography-Mass Spectrometry (GC-MS)
- CPT
- 80349 (or 80101 for qualitative screening with 80349 for confirmation)
- SNOMED
- 271149009
- Specimen volume
- 100-200 strands of hair, approximately 3-6 mm diameter pencil-width bundle, cut close to the scalp (typically 3 cm length representing approximately 3 months of growth)
- Stability
- Room temperature: stable for weeks to months. Refrigerated (2-8°C): stable for extended periods. Frozen (-20°C): stable for long-term storage. Avoid humidity and direct sunlight.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test if they suspect recent or ongoing cannabis use, especially in cases like workplace safety checks, legal disputes, or treatment evaluations. Hair provides a detailed record of exposure because cannabinoids remain in hair for weeks or months after use.
What to Expect Before the Test
No special preparation is needed. You’ll provide a small hair sample (usually from the scalp or pubic area) that will be processed in the lab. Results are typically reported as a mass concentration of cannabinoids in the hair.
How the Test Works
The test uses advanced laboratory techniques (likely high-performance liquid chromatography or a similar method) to detect and quantify cannabinoids in your hair. Hair grows continuously, so this test reflects your cannabinoid exposure over time.
What the Results Mean
Results show the concentration of cannabinoids in your hair, measured in micrograms per gram (µg/g). Higher levels may indicate recent or prolonged exposure. However, interpretation depends on clinical context (e.g., medical history, reason for testing).
Reference range
Negative: <1.0 pg/mg hair. Cutoff values may vary by laboratory and regulatory requirements (Society of Hair Testing guidelines suggest 0.1-0.2 ng/mg for screening and confirmation). Positive results require confirmation by mass spectrometry.N/A
No fasting required. Avoid chemical hair treatments (bleaching, perming, dyeing) prior to collection as these may affect analyte stability. Inform the laboratory of any hair treatments. External contamination should be minimized.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is useful for detecting cannabis use that may not be detectable in blood or urine, especially for long-term exposure. It can help determine compliance with treatment plans, assess workplace safety risks, or support legal or medical evaluations. However, results should be reviewed by a healthcare provider to understand their relevance to your situation.
Short name
Hair Cannabinoid Screening
Frequently asked questions
How long does it take to get results from this test?
Can I wash my hair before this test?
Does this test detect all types of cannabis?
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 16, 2026. · Read our editorial policy