Test ID: DTHC
Drug of Abuse, Tetrahydrocannabinol Screen with GC-MS Confirmation, Urine
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Detecting drug abuse involving delta-9-tetrahydrocannabinol (marijuana)
Reflex Tests Lists test(s) that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MSTHC | Drug of Abuse, THC Conf, U | Yes | No |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
If the tetrahydrocannabinol screen is > or =50 ng/mL, then THC confirmation is performed at an additional charge.
Method Name A short description of the method used to perform the test
DTHC/505331: Enzyme-Multiplied Immunoassay Technique (EMIT)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
DAU THC Screen, Urine
Drugs of Abuse THC Screen, Urine
Marijuana (Tetrahydrocannabinol)
Tetrahydrocannabinol DAU Screen, Urine
THC DAU Screen, Urine
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Plastic, 60-mL urine bottle
Specimen Volume: 10 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | |
| Ambient | ||
| Frozen | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Marijuana is 1 of the most widely abused drugs in the United States. It is the term for describing a leafy preparation of the plant Cannabis sativa used to produce psychic effects. A common method for the consumption of marijuana is smoking.
The primary component of marijuana is delta-9-tetrahydrocannabinoid (THC). It is the concentration of THC that determines the potency of marijuana.
Following consumption of the drug, either by inhalation or ingestion, THC is rapidly metabolized by the liver through 11-hydroxy-delta-9-THC to a series of polar metabolites, with 11-nor-delta-9-THC-alpha-carboxylic acid (THC carboxylic acid, THC-COOH) being the primary metabolite.
Approximately 80% of a dose of THC is eliminated during the first 5 days, with >65% being excreted in feces and approximately 20% excreted in urine. Depending on assay sensitivity, cannabinoid metabolites may be detected in the urine up to 10 days in occasional smokers and 30 to 40 days in chronic smokers.
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.
Negative
EMIT cutoff concentration: 50 ng/mL
Positives are reported with a quantitative GC/MS result.
Interpretation Provides information to assist in interpretation of the test results
The metabolite of marijuana (THC-COOH) has a long half-life and can be detected in urine for more than 7 days after a single use.
The presence of THC-COOH in urine at concentrations >15 ng/mL is a strong indicator that the patient has used marijuana.
The presence of THC-COOH in urine at concentrations >100 ng/mL indicates relatively recent use, probably within the past 7 days.
Levels >500 ng/mL suggest chronic and recent use.
Chronic use causes accumulation of the 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.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Moyer TP, Palmen MA, Johnson P, et al: Marijuana testing-how good is it? Mayo Clin Proc 1987;62:413-417
2. Baselt RC, Cravey RH: Disposition of Toxic Drugs and Chemicals in Man. 3rd edition. Chicago, Year Book Medical Publishers, 1989
Method Description Describes how the test is performed and provides a method-specific reference
Drug class is detected by the enzyme immunoassaytechnique. All positive screening results are confirmed by gas chromatography-mass spectrometry after extraction using a solid phase extraction procedure. (Unpublished Mayo method)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Screen:Monday through Friday, Sunday
GC-MS confirmation:Monday through Friday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
80101-Screen
G0431-Screen-government payer (if appropriate)
80299-Confirmation (if appropriate)
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 11162 | Tetrahydrocannabinols | 3530-3 |
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