What to say to a patient with a positive urine toxicology (tox) screen for amphetamines not prescribed by the current physician?

From the Guidelines

When addressing a patient with a positive urine toxicology for amphetamines not prescribed by you, it is crucial to approach the conversation with a non-judgmental tone while being direct, as this approach has been supported by recent guidelines to prioritize patient care and safety. Start by saying, "I noticed your urine test showed positive for amphetamines that I haven't prescribed. I'd like to discuss this finding to better understand your health situation and provide appropriate care." Ask if they're taking any prescribed medications from other providers, as some legitimate medications like bupropion, certain antipsychotics, or decongestants can cause false positives, as noted in 1. If they acknowledge non-prescribed amphetamine use, assess the pattern of use, reasons for use, and any associated symptoms or complications. Explain the health risks of non-prescribed amphetamine use, including cardiovascular effects, psychological impacts, and potential for dependence, which are well-documented in the literature 1.

Key Considerations

• The patient's medical history, including prescribed medications, is essential to interpret drug test results accurately, as emphasized in 1.
• Non-prescribed amphetamine use can have severe health consequences, including increased risk of stroke, as highlighted in 1.
• A thorough conversation and documentation are vital for providing appropriate care and resources, such as substance use counseling or psychiatric evaluation, as suggested in the examples.

Recommendations

• Approach the conversation with empathy and directness, focusing on the patient's health and well-being.
• Assess the patient's medication history and potential for false positives, considering the limitations of drug testing, as discussed in 1.
• Provide education on the health risks associated with non-prescribed amphetamine use, including the potential for cardiovascular and psychological complications, as noted in 1 and 1.
• Offer resources and support for substance use counseling and rehabilitation, as recommended in 1, to prioritize the patient's quality of life and reduce morbidity and mortality.

From the FDA Drug Label

False-positive urine immunoassay screening tests for amphetamines have been reported in patients taking bupropion. This is due to lack of specificity of some screening tests. False-positive test results may result even following discontinuation of bupropion therapy Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish bupropion from amphetamines. You can tell the patient that the positive urine test for amphetamines may be a false positive due to their use of bupropion. It is recommended to conduct confirmatory tests, such as gas chromatography/mass spectrometry, to distinguish between bupropion and amphetamines 2.

From the Research

Approaching the Patient

When a patient has a positive urine tox screen for amphetamines not prescribed by you, it's essential to consider the following points:

• The result may be a false positive due to various factors, including the use of certain medications or substances 3, 4, 5, 6.
• Bupropion, an antidepressant, is known to cause false-positive amphetamine screens in some immunoassay tests 3, 6.
• Atomoxetine, used to treat attention deficit hyperactivity disorder (ADHD), has also been reported to lead to false-positive amphetamine results 4.
• Other medications, such as labetalol, fenofibrate, and metformin, may also cause false-positive amphetamine screens 5.

Potential Causes of False-Positive Results

Some potential causes of false-positive amphetamine screens include:

• Use of bupropion or its metabolites 3, 6
• Use of atomoxetine 4
• Use of other medications, such as labetalol, fenofibrate, and metformin 5
• Polysubstance abuse, although this is less likely to result in a false positive 3

Next Steps

When discussing the results with the patient, consider the following:

• Ask about any medications or substances they are currently using, including prescription and over-the-counter medications, as well as any herbal supplements or vitamins.
• Consider ordering a confirmatory test, such as gas chromatography-mass spectrometry (GC-MS), to verify the results 3, 4, 5.
• Be aware of the limitations of immunoassay tests and the potential for false-positive results 5, 6.