Cite this article

NIDA. (2012, March 1). Resource Guide: Screening for Drug Use in General Medical Settings. Retrieved from

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Biological Specimen Testing

Introduction to Biological Testing

Urine drug testing is the most common toxicological test of body fluid samples in general medical settings, but you do not need to have a biological testing program to implement a drug screening program. The purpose of a biological testing program is to:

  • Confirm the presence of a drug or the use of multiple drugs.
  • Augment screening and followup conversations (i.e., biological testing should not preclude screening).

Users of biological tests should be aware that:

  • Biological tests have different windows of detection. For example:
    • A positive urine or saliva screen for cocaine and/or heroin likely indicates very recent use (past few days/past week), whereas one for marijuana could detect marijuana use anywhere from a few days to up to one month or more in the past, depending on the frequency of use..
    • It is almost impossible to determine the time of use from hair samples.
  • Not all biological screens test for all commonly abused drugs (e.g., MDMA, methadone, fentanyl, and other synthetic opioids are not included in many drug screens, and these tests must be ordered separately).
  • Biological tests examine a sample with a drug concentration at a specific cutoff level (see SAMHSA Drug Cutoff Concentrations [PDF, 49KB]). Therefore, a negative result does not mean drugs have not been used, and a positive result may at times reflect consumption of other substances (such as hemp or poppy products).
  • If tampering is a concern, specimens should be monitored for temperature or adulterants; and programs should implement and follow accurate chain-of-custody procedures.

Feedback for biological screening results:

  • Present results in a matter-of-fact way in conjunction with NIDA-Modified ASSIST feedback.
  • Re-administer the test if the patient believes the result showed a false positive.
  • If the second biological test results are positive, categorize the patient as high risk and offer a brief intervention and referral for additional assessment and possible treatment.