Toxicology Tests
What To Think About
- In general, laboratory methods are better able to detect drugs in urine than in blood. Compared to urine and blood tests, saliva tests can provide a less invasive and equally accurate way to detect drugs.
- The reliability of toxicology tests depends on the methods used by the laboratory. Occasionally drugs that have been taken are not detected (called a Reference false-negative result Opens New Window) or drugs that have not been taken are detected (called a Reference false-positive result Opens New Window).
- Results that mean drug use or abuse should always be confirmed by at least two different test methods because of the possibility of false results, the possible consequences (such as arrest or loss of a job), and the legal aspects of drug tests.
- Attempts to block or interfere with test results by drinking large amounts of water or taking other substances may be dangerous and usually do not change the test results.
- For suspected drug abuse, a trained person may need to watch the urine, blood, or saliva collection, and every person who handles the sample must sign a "chain of custody" document that is kept together with the test report. This prevents the substitution or loss of the urine, saliva, or blood sample.
- A breath test may be used to estimate blood alcohol level. For more information, see the topic Reference Self-Test for Breath Alcohol.
- Standard tests can't detect inhalant abuse. Inhalant abuse is when someone inhales or sniffs common household products to "get high." Such products include—but are not limited to—glues, nail polish remover, lighter fluid, spray paints, and cleaning fluids.
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