Test Catalog

Test Id : THCCR

Carboxy-Tetrahydrocannabinol (THC-COOH) Confirmation and Creatinine Ratio, Random, Urine

Useful For
Suggests clinical disorders or settings where the test may be helpful

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

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

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

Method Name
A short description of the method used to perform the test

THCCU: Gas Chromatography-Mass Spectrometry (GC-MS)

CRETR: Enzymatic Colorimetric Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

THC-COOH/Creatinine Ratio, U

Aliases
Lists additional common names for a test, as an aid in searching

Cannabinoids (Tetrahydrocannabinol)

CRETR

J (Jane) (Tetrahydrocannabinol)

Jane (Tetrahydrocannabinol)

Marijuana (Tetrahydrocannabinol)

Mary Jane (Tetrahydrocannabinol)

Tetrahydrocannabinol (THC) Confirmation, Quantitative, Urine

TETRAHYDROCANNABINOL, QN

THC (Tetrahydrocannabinol)

Specimen Type
Describes the specimen type validated for testing

Urine

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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. STATS are not accepted for this procedure.

Forms

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

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

6 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

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

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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

 

For confirmation of abstinence, urine analysis is a useful tool. The presence of carboxy-THC is a strong indicator that a patient has used marijuana. However, increases in urine carboxy-THC 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 carboxy-THC 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 carboxy-THC concentrations by creatinine produces a metabolite/creatinine ratio that should decrease until a new episode of drug use occurs. Carboxy-THC /creatinine ratios of specimens collected over time can be compared to determine if new marijuana use has occurred.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Carboxy-Tetrahydrocannabinol (THC):

Negative

 

Cutoff concentration:

Carboxy-THC by Gas Chromatography-Mass Spectrometry (GC-MS) <3.0 ng/mL

 

Creatinine:

> or =18 years old: 16-326 mg/dL

Reference values have not been established for patients who are less than 18 years of age.

Interpretation
Provides information to assist in interpretation of the test results

Carboxy-tetrahydrocannabinol (carboxy-THC) 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 carboxy-THC 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 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 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
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference
Recommendations for in-depth reading of a clinical nature

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 May;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 Oct;22(6):445-54. doi: 10.1093/jat/22.6.445

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

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 Oct;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

Method Description
Describes how the test is performed and provides a method-specific reference

Carboxy-Tetrahydrocannabinol:

Confirmation with quantification by gas chromatography-mass spectrometry (GC-MS).(Unpublished Mayo method)

 

Creatinine:

The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday; Varies

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 4 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

THCCU:14 days; CRETR: 7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

82570

80349

G0480, if appropriate

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
THCCR THC-COOH/Creatinine Ratio, U 19055-3
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
CRETR Creatinine, Random, U 2161-8
616334 Carboxy-THC by GC/MS 20521-1
616335 Carboxy-THC Interpretation 69050-3
616336 THC-COOH/Creatinine Ratio 19055-3

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Create a PDF

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports