How do toxicology tests work

And the test may mistake some drugs for others. For example, some cough medicines that do not contain an opioid may be identified as an opioid. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use and Privacy Policy.

Learn How this information was developed. To learn more about Healthwise, visit Healthwise. All rights reserved. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. Top of the page. Test Overview A toxicology test "tox screen" checks for drugs or other chemicals in your blood, urine, or saliva.

Why It Is Done This test may be done to: Find out if a drug overdose may be causing life-threatening symptoms, unconsciousness, or strange behaviour. It is usually done within 4 days after a drug may have been taken.

Check for drug use in the workplace. Testing is common for people who work in public safety, such as bus drivers or child care workers. Some jobs require a tox screen as part of the hiring process. Look for the use of drugs that enhance athletic ability. Check for the presence of a date rape drug. How To Prepare Many medicines can change the results of this test.

How It Is Done Blood test The health professional taking a sample of your blood will: Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein. Clean the needle site with alcohol. Put the needle into the vein. More than one needle stick may be needed. Attach a tube to the needle to fill it with blood.

Remove the band from your arm when enough blood is collected. Put a gauze pad or cotton ball over the needle site as the needle is removed. Put pressure on the site and then put on a bandage. Random urine sample collection A random urine sample collection may also be called a urine drug screen.

How It Feels Blood test The blood sample is taken from a vein in your arm. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. It looks like your browser does not have JavaScript enabled. Please turn on JavaScript and try again. Important Phone Numbers. Top of the page. Test Overview A toxicology test "tox screen" checks for drugs or other chemicals in your blood, urine, or saliva.

Why It Is Done This test may be done to: Find out if a drug overdose may be causing life-threatening symptoms, unconsciousness, or strange behaviour. This test will be done right away in this situation. A toxicology test can also be done up to days after a possible overdose.

Check for drug use in the workplace. Testing is common for people who work in public safety, such as bus drivers or child care workers. Some jobs require a toxicology screen as part of the hiring process. Check for drug use in students involved in extracurricular activities, such as sports and cheerleading.

Look for the use of drugs that enhance athletic ability. Check for the presence of a date rape drug. How To Prepare Many medicines can change the results of this test. How It Is Done Blood test A health professional uses a needle to take a blood sample, usually from the arm. Clean-catch midstream urine collection Collecting the urine this way keeps the sample from being contaminated.

Wash your hands to make sure they are clean before you collect the urine. If the collection cup has a lid, remove it carefully. Set it down with the inner surface up. Do not touch the inside of the cup with your fingers. Clean the area around your genitals. For men: Pull back the foreskin, if you have one.

Most toxicology screens provide limited information about how much or how often someone has taken a drug. The results of a toxicology screen are usually positive or negative. A positive test result means that a drug or multiple drugs are present in the body.

Once your doctor identifies the presence of a drug by screening, a more specific test may be done that can show exactly how much of the drug is present. A team at Newcastle University in the UK has developed a new testing technique that uses human tissue to measure drug reactions.

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When needed, there are specialty toxicology labs that can test for virtually any potential toxin or metabolite in almost every kind of post-mortem sample. A laboratory should be accredited to perform the analytical work and must be subject to regular inspections by approved accreditation personnel.

Certification for forensic toxicology laboratories in the United States and Canada is also available through ABFT, and is voluntary and additional to accreditation. All laboratory tests must be validated, fully documented and fit for purpose. This will ensure that laboratory can reproduce accurate and reliable results for medicolegal investigations. All laboratory tests should conform to standard operating procedures, results are confirmed to meet standards, and reported results are peer reviewed by a second toxicologist before being released.

Immunoassays - Most commonly used drug screening tests involve immunoassay techniques. Immunoassays are laboratory tests that use antibodies to detect a reaction with specific substances. Immunoassay screening tests are designed to detect whether a sample is positive or negative for the targeted drug. Four interpretations of a screening drug test are possible:. For those samples that give positive screening results, confirmation tests should be performed, preferably using mass spectrometry MS detection.

This is the definitive technique used in toxicology to establish proof of structure of unknown substances. Systematic toxicological analysis - The usual practice in toxicological examination begins with the preliminary identification of alcohol and screening of a wide spectrum of acidic, neutral and basic organic drugs or poisons.

If a toxin is detected, confirmatory and, if necessary, quantitative testing has to be performed. Quantitative testing determines how much of the substance is involved.

In general, a positive identification is achieved using at least two independent analyses and preferably using different testing methods. A chromatographic confirmation test could also determine quantification, simplifying the testing process. Acetone can derive from abnormal body metabolism in diabetic ketoacidotic states.

Specimen collection Table 1 below provides a snapshot of the kinds of samples commonly requested when investigating different manners of death, although there may be unique case needs that have to be addressed for some investigations. Table 1.