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Test Code THCCU Delta-9-Carboxy-Tetrahydrocannabinol Confirmation and Creatinine Ratio, Random, Urine


Specimen Required


Only orderable as part of a profile. For more information see THCCR / Delta 9-Carboxy-Tetrahydrocannabinol (THC-COOH) Confirmation and Creatinine Ratio, Random, Urine

 

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.


Secondary ID

616334

Useful For

Measuring the delta-9 carboxy-tetrahydrocannabinol (delta-9-THC-COOH) to creatinine ratio as a part of a profile

Method Name

Only orderable as part of a profile. For more information see THCCR / Delta 9-Carboxy-Tetrahydrocannabinol (THC-COOH) Confirmation and Creatinine Ratio, Random, Urine

 

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

Reporting Name

THC-COOH/Creatinine Ratio, U

Specimen Type

Urine

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

Reject Due To

Gross hemolysis OK
Gross icterus Reject

Clinical Information

Delta-9-tetrahydrocannabinol (THC) is the active agent of the popularly abused/used drug, cannabis/marijuana.

 

Following consumption of the drug, either by inhalation or ingestion, it is metabolized to a variety of inactive chemicals, one of them being delta-9-tetrahydrocannabinol carboxylic acid (delta-9-THC-COOH).

 

For confirmation of abstinence, urine analysis is a useful tool. The presence of delta-9-THC-COOH is a strong indicator that a patient has used cannabis/marijuana. However, increases in urine delta-9-THC-COOH concentrations resulting from changes in urinary output may be mistakenly interpreted as new drug use rather than carryover from previous drug exposure. Individuals continue to excrete THC-COOH for days after abstinence, and although concentrations generally decrease with time, the concentrations can fluctuate with levels of hydration. As a result, the division of urinary delta-9-THC-COOH concentrations by creatinine produces a metabolite/creatinine ratio that should decrease until a new episode of drug use occurs. Delta-9-THC-COOH/creatinine ratios of specimens collected over time can be compared to determine if new cannabis/marijuana use has occurred.

Reference Values

Only orderable as part of a profile. For more information see THCCR / Delta 9-Carboxy-Tetrahydrocannabinol (THC-COOH) Confirmation and Creatinine Ratio, Random, Urine

 

Not detected

 

Cutoff concentration:

<5.0 ng/mL

Interpretation

Delta-9 carboxy-tetrahydrocannabinol (delta-9-THC-COOH) and creatinine concentrations must be obtained for at least 2 urine specimens with a known time interval (1-7 days) between collections. Using these creatinine-normalized delta-9-THC-COOH concentrations, a ratio is calculated between the concentration of any urine specimen (U2) divided by the concentration in a previously collected urine specimen (U1). The most conservative method for reporting new cannabis/marijuana use between collections would apply a U2/U1 decision ratio equal to the maxima listed in Table 1. A more realistic decision ratio with reasonable certainty would be to use the 95% below limits in the same table. U2/U1 ratios above these limits would indicate new usage between those collection time points.

 

Table 1. Adapted from Smith ML et al. for less than daily users of cannabis/marijuana.(1)

 

Time interval between urine collections (hours)

Maximum ratio (U2/U1)

95% Below (U2/U1)

0-23.9

6.29

1.42

24-47.9

2.27

1.01

48-71.9

1.47

0.853

72-95.9

1.63

0.595

96-119.9

0.555

0.347

120-143.9

0.197

0.146

144-167.9

0.080

0.073

Cautions

No significant cautionary statements

Clinical Reference

1. Smith ML, Barnes AJ, Huestis MA. Identifying new cannabis use with urine creatinine normalized THCCOOH concentrations and time intervals between specimen collections. J Anal Toxicol. 2009;33(4):185-189. doi:10.1093/jat/33.4.185

2. Huestis MA, Cone EJ. Differentiating new marijuana use from residual drug excretion in occasional marijuana users. J Anal Toxicol. 1998;22(6):445-454. doi:10.1093/jat/22.6.445

3. Langman LJ, Bechtel LK, Holstege CP. Clinical toxicology. In: Rifai N, Chiu RWK, Young I, Burnham CAD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:chap 43

Method Description

This test includes immunoassay and confirmation with quantification by liquid chromatography tandem mass spectrometry.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

CPT Code Information

80349

G0480, if appropriate

LOINC Code Information

Test ID Test Order Name Order LOINC Value
THCCU THC-COOH/Creatinine Ratio, U 19055-3

 

Result ID Test Result Name Result LOINC Value
616334 Delta-9 Carboxy-Tetrahydrocannabinol by LC-MS/MS 20521-1
616335 Carboxy-THC Interpretation 69050-3
616336 THC-COOH/Creatinine Ratio 19055-3