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HelpTest 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, USpecimen Type
UrineSpecimen Minimum Volume
6 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days | ||
| Ambient | 72 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.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 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
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 |
Cautions
No significant cautionary statements
Method Description
Delta-9 Carboxy-Tetrahydrocannabinol:
Confirmation with quantification by liquid chromatography tandem mass spectrometry.(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)
Day(s) Performed
Monday through Friday
Report Available
2 to 4 daysPerforming 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 |