General Guidelines

General Guidelines to Consider for Toxicological Testing

Both targeted drug assays and comprehensive panels (7 to over 200 drugs) exist with various reference labs, and may include screening and confirmatory techniques and can test many common biologic matrices (urine, hair, blood, etc).

Urine Drug or Toxicology Screens

Urine Drug Screens are usually urine immunoassay/ELISA based tests, which are sensitive but not specific, and provide information on if a substance was present (qualitative), but not concentrations of the substance (quantitative). Urine Drug Screens can commonly test for: amphetamines, methamphetamines, MDMA (“ecstasy”), benzodiazepines, barbiturates, opiates, marijuana/THC, PCP, LSD, cocaine.

Each manufacturer/brand of Urine Drug Screen can be different.
Urine Drug Screens can have false positives and negatives. Discuss with the specific laboratory what could be common false positives/negatives that may be specific for the commercial test used.

Types of Tests

Neonatal Testing

Testing Children

Test Results

Confirmatory Testing

Confirmatory testing is the gold standard, can be from any matrix (urine, blood, hair, meconium, umbilical cord), and is usually High-Performance Liquid Chromatography (HPLC) or Gas Chromatography (GC) paired with mass spectroscopy (MS). It is a specific test, meaning false positives and negatives are rare, and can determine drug specific exposure.

Confirmatory screening is recommended for most unexpected results, or concerns for positive exposures in children.
Some reference labs will reflexively send confirmatory results when screening tests are positive, but check with your reference labs.

Drug Concentrations

Urine drug concentrations (also known as levels) are difficult to interpret clinically and they are rarely useful in determining the level of intoxication or exposure route. Blood drug concentrations can be a better indicator of potential level of intoxication. However, this can vary based on the the drug itself, as well as chronicity and timeline of use.

Detection of a systemic drug exposure in a child is of concern, regardless of the concentration whether in the urine or blood.

Details will vary based on the substance, the patient, and the testing panel. If there are any question or concerns on results or interpretation of a toxicological test (whether positive or negative results, or what test to order), please consult the lab and/or a medical specialist.