When is a toxicology test done

In: Rifai N, ed. St Louis, MO: Elsevier; chap Substance abuse. Philadelphia, PA: Elsevier; chap Medical toxicology. Conn's Current Therapy Philadelphia, PA: Elsevier; ; Toxicology and therapeutic drug monitoring. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

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Any duplication or distribution of the information contained herein is strictly prohibited. Information developed by A. Please discuss with your doctor any questions or concerns you may have. Medical Tests. Definition A toxicology screen refers to various tests that determine the type and approximate amount of legal and illegal drugs a person has taken. Officials can also order a test for people who are being monitored for illegal drug use, such as individuals on probation.

Other situations in which a toxicology screen may be performed include the following:. No special preparation is required for a toxicology screen. Certain medications can interfere with the test results. A toxicology screen often requires a urine sample. The urine is collected in a small cup.

In some cases, law enforcement or medical personnel are present to prevent tampering. You may be asked to remove outerwear such as a jacket, hat, or sweater and to empty your pockets as a precaution against tampering. A blood sample may also used to screen for drugs. This type of test involves drawing blood into one or more small tubes.

During a blood test, a healthcare professional inserts a needle into a vein and removes blood. Compared with a urine test, a blood test is more accurate in determining the concentration of a particular drug. In some cases, a toxicology screen might be performed using a saliva or hair sample. The contents of the stomach can also be screened for drugs when doctors suspect someone has taken a drug orally.

Many substances can be discovered through toxicology screens. Common classes of drugs that may be detected by toxicology screens include:. Depending on the drug, it may show up in the blood or urine within a few hours or weeks after being ingested. Certain substances, such as alcohol, are eliminated from the body fairly quickly. Other drugs, however, can be detected for several weeks after being used. One example is THC, which is in marijuana. 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. When there are no obvious signs of death, as in the case of Prince, a toxicology test is needed to determine the cause of death. Contrary to representations by TV crime shows, these tests are complex and can take several weeks to complete.

First of all, it is important to distinguish the different types of toxicology tests. Hospital toxicology screenings are usually simple tests that look for the presence of drugs of abuse in the urine and, occasionally, the blood.

Toxicology tests performed for autopsies are called forensic or post-mortem toxicology tests. Experts also measure the amount of drugs and look to see if the concentration is of a lethal dosage. During an autopsy, a pathologist collects samples of blood, various tissues and, if present, urine. Usually, pathologists collect blood from multiple areas of the body.

Tissue samples might be taken from the liver, brain, spleen, kidney and the eyes. Once the samples are collected, they are tested by medical examiner personnel in laboratories that are accredited by the CAP or other organizations to maintain quality standards.

Pathologists, toxicologists and chemists work together during this process, which can involve several rounds of tests.