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Test Code THCCR Delta 9-Carboxy-Tetrahydrocannabinol (THC-COOH) Confirmation and Creatinine Ratio, Random, Urine


Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Collection Container/Tube: Plastic urine container

Submission Container/Tube: 10-mL tube

Specimen Volume: 10 mL

Collection Instructions:

1. Collect a random urine specimen.

2. Submit 10 mL in a plastic container.

3. No preservative.

Additional Information:

1. No specimen substitutions.

2. Submitting less than 10 mL may compromise the ability to perform all necessary testing.

3. STAT requests are not accepted for this test.


Useful For

Measuring the delta-9 carboxy-tetrahydrocannabinol to creatinine ratio to detect use of tetrahydrocannabinol

Profile Information

Test ID Reporting Name Available Separately Always Performed
THCCU THC-COOH/Creatinine Ratio, U No Yes
CRETR Creatinine, Random, U No Yes

Method Name

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

CRETR: Enzymatic Colorimetric Assay

Reporting Name

THC-COOH/Creatinine Ratio, U

Specimen Type

Urine

Specimen Minimum Volume

6 mL

Specimen Stability Information

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

Reference Values

Carboxy-Tetrahydrocannabinol (THC):

Not Detected

 

Cutoff concentration:

Delta-9 Carboxy-tetrahydrocannabinol by liquid chromatography tandem mass spectrometry: <5.0 ng/mL

 

Creatinine:

≥18 years old: 16-326 mg/dL

Reference values have not been established for patients who are younger than 18 years.

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 the Table. 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. 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

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):185-9. 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):445-54. 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

4. Delaney MP, Lamb EJ. Kidney disease. In: Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:1256-1323

5. Meeusen J, Rule A, Voskoboev N, Baumann N, Lieske J. Performance of cystatin C- and creatinine-based estimated glomerular filtration rate equations depends on patient characteristics. Clin Chem. 2015;61(10):1265-1272. doi:10.1373/clinchem.2015.243030

6. Newman DJ, Price CP. Renal function and nitrogen metabolites. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders Company; 1999:1204-1270

7. Kasiske BL, Keane WF. Laboratory assessment of renal disease: clearance, urinalysis, and renal biopsy. In: Brenner BM, ed. The Kidney. 6th ed. WB Saunders Company; 2000:1129-1170

Day(s) Performed

Monday through Friday

Report Available

2 to 4 days

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

82570

80349

G0480, if appropriate

LOINC Code Information

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

 

Result ID Test Result Name Result LOINC Value
CRETR Creatinine, Random, U 2161-8
616334 Delta-9 Carboxy-Tetrahydrocannabinol by LC-MS/MS 20521-1
616335 Carboxy-THC Interpretation 69050-3
616336 THC-COOH/Creatinine Ratio 19055-3

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.