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EPIC CODE: LAB447 Delta-8 and Delta-9-Carboxy-Tetrahydrocannabinol (THC) Confirmation, Random, Urine

Additional Codes

Sunquest: THCUM
Mayo:        THCU

Reporting Name

Carboxy-THC Confirmation, U

Useful For

Detection and confirmation of drug use of cannabis/marijuana and will specifically identify and quantify delta-8-THC-COOH and delta-9-THC-COOH

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Ordering Guidance

1. For situations where chain of custody is required, a Chain-of-Custody Kit (T282) is available. For chain-of-custody testing, order THCX / Carboxy-Tetrahydrocannabinol (THC) Confirmation, Chain of Custody, Random, Urine.

2. Additional drug panels and specific requests are available. Call 800-533-1710 or 507-266-5700.

3. If urine creatinine is required or adulteration of the sample is suspected, order, ADULT / Adulterants Survey, Random, Urine.

Specimen Required

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container Tube: Plastic urine container

Submission Container/Tube: Plastic, 5-mL tube

Specimen Volume: 3 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.

Additional Information:

1. No specimen substitutions.

2. STAT requests are not accepted for this test.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
  Frozen  14 days
  Ambient  72 hours

Reference Values

Not Detected


Cutoff concentration:



Day(s) Performed

Monday through Friday

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


G0480 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
THCU Carboxy-THC Confirmation, U 20521-1


Result ID Test Result Name Result LOINC Value
618770 Delta-8 Carboxy-Tetrahydrocannabinol by LC-MS/MS 20521-1
2497 Delta-9 Carboxy-Tetrahydrocannabinol by LC-MS/MS 20521-1
21186 Carboxy-THC Interpretation 69050-3

Clinical Information

There are over 100 different cannabinoids in cannabis/marijuana. The main psychoactive cannabinoid is delta-9-tetrahydrocannabinol (delta-9-THC), which is the active agent of the popularly abused street drug, cannabis/marijuana. Delta-8 tetrahydrocannabinol (delta-8 THC) is another psychoactive substance found in the Cannabis sativa plant, of which cannabis/marijuana and hemp are 2 varieties. Delta-8 THC is one of over 100 cannabinoids produced naturally by the cannabis plant but is not typically found in significant amounts in the plant itself. As a result, concentrated amounts of delta-8 THC are typically manufactured from hemp-derived cannabidiol.


Following consumption of cannabis/marijuana, delta-9-THC metabolizes to a variety of inactive products, one of them being the carboxy metabolite (delta-9-THC-COOH). In almost all medico-legal cases or when the patient adamantly denies cannabis/marijuana use and the immunoassay test is positive, confirmation of the result by a definitive test is required. This test is a definitive, confirmatory test using liquid chromatography tandem mass spectrometry to identify and quantify delta-8-THC-COOH and delta-9 THC-COOH.


The presence of delta-8 and/or delta-9 carboxy tetrahydrocannabinol (THC-COOH) in urine is a strong indicator that the patient has used cannabis/marijuana.


THC-COOH has a long half-life and can be detected in urine for more than 7 days after a single use.


Chronic use causes accumulation of THC and THC-COOH in adipose tissue, such that it is excreted into the urine for as long as 30 to 60 days from the time chronic use is halted.


No significant cautionary statements

Clinical Reference

1. Baselt RC: Disposition of Toxic Drugs and Chemicals in Man. 12th ed. Biomedical Publications; 2020

2. Langman LJ, Bechtel LK, Meier BM, Holstege C: Clinical toxicology. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:832-887

Method Description

Carboxy tetrahydrocannabinol (THC-COOH) is extracted from urine by making the urine alkaline to hydrolyze THC-COOH glucuronide. The hydrolyzed samples are diluted for analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) using selected ion monitoring. (Unpublished Mayo method)

Report Available

3 to 5 days

Specimen Retention Time

2 weeks

Reject Due To

Gross hemolysis OK
Gross icterus Reject

NY State Approved


Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)


If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-General Request (T239)

-Therapeutics Test Request (T831)