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Frequently Asked Questions


  • Q: A patient that is being prescribed oxycodone tested negative according to the laboratory. Should we confront the patient with diversion?

    A: The lab results support that the patient has not recently taken their oxycodone. The reason could be prescription diversion, medication hoarding, finishing prescription ahead of time, etc. Regardless of the reason, the negative lab result the action to interview and discover why the medication has not recently been taken.


  • Q: My patient is on a benzodiazepine. Will the laboratory test measure the drug in urine?

    A: Our urine drug testing will detect most benzodiazepines. Their metabolism is complex and many benzodiazepines have poor detection by immunoassay techniques including the Rapid Test Cup. Our laboratory confirms samples by mass spectrometry, which has excellent detection limits for benzodiazepines. We strongly recommend that all Rapid Test Cup results be confirmed by mass spectrometry.


  • Q: My patient’s Rapid Test Cup screening sample resulted in a positive result for methamphetamine and the laboratory result came back negative when tested by mass spectrometry (MS). Which is the correct patient result?

    A: The Rapid Test Cups use immunoassay test strips which are prone to false positive results. This is the reason why samples are sent to the laboratory to confirm all drug test results by mass spectrometry. The mass spectrometry result from the laboratory is the correct result because it is a very sensitive and accurate test. In this specific case, pseudoephedrine, found in cold medicines, can cause a false positive for methamphetamine.


  • Q: My patient is being prescribed hydrocodone and the laboratory results came back positive for hydrocodone and hydromorphone. Should I be concerned about abuse?

    A: No, this is lab result is consistent with the medication prescribed because hydromorphone is a metabolite of hydrocodone.


  • Q: Recently we had a patient who ran out of her prescription of Morphine and she hadn’t taken it for 4 days. The Rapid Test Cup showed negative and the laboratory report came back negative as well. I’m surprised on the negative result from the laboratory?

    A: The approximate urine retention time for Morphine is 48-72 hours. Over the course of 4 days (96 hours), the body likely removed all of the morphine explaining the reason for the negative result. It is important to note the urine retention times with relation to specimen collection when interpreting the results.


  • Q: My patient is on Vicodin and the test results show positive for morphine. Is this consistent with the prescription regimen?

    A: Vicodin is Hydrocodone and is not metabolized into morphine. The test subject is adulterating that prescription with morphine.


  • Q: My patient has been prescribed Fentanyl, but the laboratory report reads that no Fentanyl was found in the urine. The report also reads positive for Norfentanyl. What do I make of these results?

    A: Norfentanyl is the primary metabolite of Fentanyl and Norfentanyl is generally present at approximately 5-10x higher concentrations in urine than the parent Fentanyl. It is possible that the concentration of Fentanyl was too low for the mass spectrometry equipment to detect. However the presence of Norfentanyl indicates that the patient is taking their Fentanyl prescription.


  • Q: What is the difference between a false positive and a false negative?

    A: A false positive is a positive test result for a drug, but the drug is not actually present. A false negative is a negative test result indicating the absence of a drug, but the drug is actually present. Rapid Test Cups are prone to both false positives and false negatives which is why the results are confirmed in the laboratory. False positives are commonly caused by other substances cross-reacting with the immunoassay strips used in the Rapid Test Cups. False negatives are commonly to the Rapid Test Cup because their limit of detection is high. Mass spectrometry, which is used in the laboratory, has a much lower limit of detection and will be able to find much lower concentrations of drugs.


  • Q: I screened a patient using the Rapid Test Cup and it was negative. Is it reasonable to assume the patient is compliant?

    A: Not necessarily. Aside from the propensity of the Rapid Test Cup for false negatives, point of care tests only examine the urine for a limited number of drugs and drug classes. There are many others drugs a patient may be taking that will not be discovered with a Rapid Test Cup, such as buprenophrine, fentanyl, and carisoprodol. When sent to the laboratory these and many other drugs can be detected at much lower concentrations by using mass spectrometry. Therefore, the Rapid Test Cup is a great quick screening device, but further laboratory testing is recommended.


  • Q: If the Rapid Test Cup is prone to false negatives and false positives, why even use it if the specimen will be sent to the laboratory anyway?

    A: Understandable logic, but the reality is that the Rapid Test Cup is still a great tool to provide instantaneous results at the time of the office visit. Take a scenario in which the patient tests positive for an illicit drug like cocaine. Although the result should be sent in for confirmation at the laboratory, that quick result does give the clinician additional information to make better decisions at the time of treatment.


  • Q: A patient that is being prescribed oxycodone tested negative according to the laboratory. Should we confront the patient with diversion?

    A: The lab results support that the patient has not recently taken their oxycodone. The reason could be prescription diversion, medication hoarding, finishing prescription ahead of time, etc. Regardless of the reason, the negative lab result warrants an interview to discover why the medication has not recently been taken.


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