To indicate whether the result is positive, negative, or even inconclusive for the evidence of drug use, hair follicle drug testing uses cutoff levels. A laboratory uses two test methods to determine the drug level in someone’s body: screening and confirmation.
Every laboratory may generate a positive result with the cutoff levels, which are not standard due to some factors. Then, what is the cutoff level that indicates a positive test result for the presence of drug use in someone’s body with a hair follicle drug test? Okay, let’s see the hair follicle drug test results chart below!
Chart for Hair Follicle Drug Test Result
An organization promoting research in hair follicle drug testing called the Society of Hair Testing has proposed the cutoff levels, which are stated in nanograms (ng) per milligram (mg). The following are the cutoff levels for the most commonly tested hair follicle drug substances:
|
Hair Follicle Drug Test Results |
||
|
Substance Detected |
Initial Cutoff Levels |
Confirmatory Cutoff Levels |
| Cocaine and drug metabolites | 0.5 ng/ mg | Cocaine: 0.5 ng/mg
Cocaine Metabolites: 0.05 ng/mg |
| Marijuana Metabolites | 0.1 ng/ mg | THC: 0.05 ng/mg
THC-COOH: 0.0002 ng/mg |
| Amphetamines and drug metabolites | 0.2 ng/ mg | Amphetamine: 0.2 ng/mg
Methamphetamine: 0.2 ng/mg MDA: 0.2 ng/mg MDMA: 0.2 ng/mg |
| Opiates and drug metabolites | 0.2 ng/ mg | Morphine: 0.2 ng/mg
Codeine: 0.2 ng/mg 6-acetylmorphine (heroin metabolite): 0.2 ng/mg Methadone: 0.2 ng/mg EDDP (methadone metabolite): 0.05 ng/mg Buprenorphine: 0.01 ng/mg Norbuprenorphine: 0.01 ng/mg |
How to Interpret the Hair Follicle Drug Test Result?
An individual can learn about their test results through the organization that required testing or a healthcare professional. However, they can also learn to understand hair follicle test results by themselves. Of course, the results of the hair follicle drug test will be shown as positive, negative, or even inconclusive.
1. Positive test result
If the test result indicates positive, it means that no drug substance or drug metabolite was detected in the sample of hair used for testing. The test result may vary among laboratories since there is no standard positive cutoff level for all laboratories yet.
Keep in mind that hair samples that generate a positive result for ELISA testing will be performed for a second test, such as GC-MS. A positive test result with confirmatory testing means that the presence of a specific substance in someone’s hair sample has been confirmed by the laboratory.
2. Negative test result
If the test result is negative, it indicates that no drugs or drug metabolites were found in the hair samples or after a positive ELISA screening. A negative test result may also indicate that the person did not consume the drug targeted by the hair follicle test or that the sample of hair used for testing cannot detect the amount of drug that has been consumed.
However, it does not mean that someone has not used any drugs. He might have used the drug recently, so the substance may not have appeared in the hair when the hair follicle drug test was carried out. Or he could also have used other drugs that cannot be screened by hair follicle testing.
3. Inconclusive
If the test result is inconclusive, it can indicate that the sample of hair might have been contaminated or that something went wrong during testing. In some cases, the laboratory examiner may ask for a new hair sample for testing.
What Methods Are Used to Carry Out Hair Follicle Drug Testing?
You need to know that the result of the drug test with hair follicles will be available within a few business days once the laboratory accepts the sample of hair. Since the test uses two laboratory methods, processing times may vary among the laboratories.
It will be more helpful to understand the laboratory methods used for hair follicle testing when you try to interpret the results. A laboratory usually uses a two-tier method for hair follicle drug testing. It means that there’s an initial screening on the first step and then another test as a confirmatory method on another part of the original sample.
The following are two methods used for hair follicle drug testing:
Method 1: Initial Test Methods
The initial test method, known as Immunoassay is a common method used for drug testing with hair follicles. It only provides preliminary results, which include drugs or drug substances that are detected above the laboratory’s cutoff level for positive results.
Well, the positive test result must be followed by testing with a confirmatory test method. This method aims to reduce the risk of inaccurate results on initial testing.
Method 2: Confirmatory Test Method
The confirmatory test method is used for more thorough testing, which requires more definitive processes, including chromatography-mass spectrometry. This method aims to identify and measure specific drugs in the sample. This method definitely provides more detailed results than the initial test method, including specific metabolites that are detected in hair.
To comply with regulatory standards, it is very important that cutoff levels are chosen based on the substance tested for. If a substance is identified at concentration levels that are equal to or greater than the cutoff, it will be reported as a positive result by the laboratory. We must say that a negative test does not always mean that there was no drug indicated— it’s just that the amount is lower than the cutoff levels.
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