S2 Ep7: #18 Urine Drug Testing with Dr. Timothy Wiegand
Aug 17, 2023
auto_awesome
Toxicologist Dr. Timothy Wiegand discusses interpreting urine drug tests (UDT), false positives, and counseling patients prior to ordering the test. Topics include detection windows, interpreting opiates and opioids in UDT, resources for interpretation, discussing results with patients, buprenorphine testing, specimen validity testing, and saliva testing.
There are two types of drug tests: screening and confirmatory, with screening tests being rapid but prone to false positives, and confirmatory tests being more accurate but time-consuming and expensive.
Certain medications can cause false positives in drug tests, such as antidepressants and decongestants, so confirmatory testing should be considered to ensure accurate results.
When discussing urine drug test results with patients, it is important to approach the conversation with support, understanding, and without stigmatizing or shaming the patient based on the test results.
Deep dives
Screening and Confirmatory Drug Tests
There are two types of drug tests: screening and confirmatory. Screening tests are preliminary tests that use antibody technology to detect specific substances in urine. They are rapid, less expensive, and provide quick results. However, they can have false positives due to cross-reactivity with certain substances. Confirmatory tests, on the other hand, use chromatography and mass spectroscopy to identify and quantify specific drugs and their metabolites. These tests are more expensive, time-consuming, and provide accurate results. Confirmatory tests are used when the results impact patient care, such as legal issues or compliance monitoring.
Common False Positives in Drug Tests
Certain medications can lead to false positives in drug tests. For example, antidepressants like sertraline and bupropion can cross-react with amphetamine or methamphetamine assays, causing false positives. Pseudoephedrine, found in some decongestants, can also trigger false positives for methamphetamine. Additionally, medications like naltrexone and naloxone can cause false positives in oxycodone screening tests. It is important to be aware of these potential false positives and consider confirmatory testing to ensure accurate results.
Interpreting Unanticipated Findings in Urine Drug Tests
When discussing unanticipated findings in urine drug tests with patients, it is crucial to approach the conversation with support and understanding. Avoid accusatory language and emphasize that the test results are part of the clinical information used to support the patient's well-being. It is essential to provide context and explain the meaning behind the test results. The discussion should focus on the patient's health and progress, rather than stigmatizing or shaming them based on the test results.
Interpreting Opioid Screens
Opioid screens are commonly used in drug testing, but they may not include all opioids. The opiate screen typically detects chemicals derived from poppy, such as morphine, diacetyl morphine (heroin), and their metabolites. Synthetic opioids, like hydrocodone and hydromorphone, which are structurally similar to opiates, can also be detected. However, interpreting the results can be challenging, as positive screens could be due to current or past use of various opioids. Confirmation testing is often required to accurately identify specific opioids present.
Interpreting Benzodiazepine Screens
Benzodiazepine screens are targeted towards detecting oxazepam, a common metabolite of many benzodiazepines. However, not all benzodiazepines, like clonazepam, will cross-react with this assay. To detect clonazepam, it is necessary to order a specific test. False positives can occur with the presence of other medications, such as sertraline, or with designer benzodiazepines. Confirmation testing is crucial to confirm specific benzodiazepines present in the screen. Additionally, specimen validity testing is essential to ensure the sample is valid, free from dilution, and not influenced by external substances or modifications.
Interpret urine drug tests (UDT) like a toxicologist! Learn how to approach interpreting positive opiates, opioids, and benzodiazepines in UDT. We discuss the nuances of interpreting UDT, false positives, and how to counsel a patient prior to ordering the test. We’re joined by Dr. Timothy Weigand @TwToxMD (University of Rochester Medical Center).
Claim free CME for this episode at curbsiders.vcuhealth.org!
By listening to this episode and completing CME, this can be used to count towards the new DEA 8-hr requirement on substance use disorders education.
