Episode 157: Urine Testing This episode includes the pitfalls of urine tests, how to detect adulterated urine, and more. Written by Janelli Mendoza, MSIV, Ross University School of Medicine. Editing by Hector Arreaza, MD. Comments by Carol Avila, MD.
Episode 157: Urine Testing
This episode includes the pitfalls of urine tests, how to detect adulterated urine, and more.
Written by Janelli Mendoza, MSIV, Ross University School of Medicine. Editing by Hector Arreaza, MD. Comments by Carol Avila, MD.
You are listening to Rio Bravo qWeek Podcast, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California, a UCLA-affiliated program sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. This podcast was created for educational purposes only. Visit your primary care provider for additional medical advice.
Introduction: Urine drug screenings are valuable tools used every day by physicians to monitor illicit substance use, as well as proper use or misuse of prescription drugs. However, studies suggest that physicians using “clinical judgment” on who and when to test is often wrong and confounded by implicit racial bias. The implications of this are an inappropriate discontinuation of treatment.
For example, a study by Gaither, Gordon, and Crystal et. al found that compared to white patients, black patients were 10% more likely to undergo urine drug screening. In addition, they were 2-3 times more likely to have long-term opioid medication abruptly discontinued as a result of a UTOX positive for marijuana.
False positive urine tests:
Before getting into the current guidelines, let’s discuss the interpretation of Urine Drug Screenings. It’s important to be aware of prescription drugs that may cause false positives:
· Bupropion, labetalol, pseudoephedrine, trazodone → Amphetamines
· HIV antivirals, sertraline → Benzodiazepines
· HIV antivirals, NSAIDs, PPI’s → Cannabinoids
· Diphenhydramine, Naloxone, Quetiapine, Quinolones, Verapamil → Opioids
· Dextromethorphan, diphenhydramine, ibuprofen, tramadol, venlafaxine → Phencyclidine
Tampering of urine: Other factors to consider are the tampering of collected urine. The tampering of collected urine may include diluting the urine, or adding other chemicals and substances. Laboratory results that should prompt consideration of adulteration are: Creatinine <20 mg/dL, pH <3 or >11, Specific gravity <1.001 or > 1.035, Temp <90 F or > 100 F
How long urine tests are positive:
The detection window for common substances in urine drug screenings are as follows:
· Amphetamines: 2-3 days
· Cocaine: 1-2 days
· Opioids: 1-3 days, but up to 14 days if the patient is on methadone.
· Phencyclidine: up to or less than 1 week, may be longer if chronic use.
Cannabinoids are a little different as the THC component builds up and is stored in adipose tissue. Therefore, a patient's weight, body fat percentage, exercise level, and diet can all influence the detection window. This is more so an issue for chronic daily users.
· For single-time use: 2-3 days.
· Daily use: 2-4 weeks
· Chronic heavy use: >6-8 weeks as we said, the exact time will be influenced by many factors depending on how long it takes to deplete THC molecules stored in adipose tissue.
Monitoring use of prescription drugs:
Dr. John Hayes and Dr. Kristen Fox at the Department of Family Medicine and Community Medicine College of Wisconsin have developed a patient-centered approach in utilizing urine drug screenings for monitoring the use of controlled prescription drugs. If physicians should not test based on suspected misuse of medications, then when should they test?
The frequency of screening should be determined based on a patient’s risk for substance use disorder. This will be determined by use of evidence-based tools such as a risk calculator. On MD calc, clinicians can find the ORT (Opioid Risk Tool for Narcotic Abuse) created by Dr. Lynn Webster. This stratifies patients into high-risk, moderate risk and low- risk of opioid related aberrant behaviors. Factors contributing to high-risk include age between 16-45, history of preadolescent sexual abuse, history of depression, history of ADD, OCD, Bipolar disorder, or schizophrenia, illicit substance use, history of misuse of prescription drugs. Family history also significantly contributes to risk assessment independently taking into consideration FHx of alcohol abuse, illicit substance abuse, and prescription drug misuse.
How often can we test the urine for patients on controlled medications?
Based on the risk assessment the frequency of Urine drug screenings for patients on controlled medications should be as follows:
· Low- risk patients should be tested annually
· Moderate-risk patients should be tested at least 2x per year
· High-risk patients should be tested at least 3x per year
Based on the results, if it is found that a patient is recurrently misusing their medication, rather than abruptly discontinuing a patient off of their medication, it is recommended that the provider share their concern with the patient to initiate an open discussion. Medication should be tapered, and the patient should receive a referral and support from an addiction specialist.
Unhealthy Drug Use: Screening by USPSTF (published on June 09, 2020):For adults age 18 years or older, the USPSTF recommends screening by asking questions about unhealthy drug use. Testing biological specimens is not recommended for this purpose. “Screening should be implemented when services for accurate diagnosis, effective treatment, and appropriate care can be offered or referred.”
Conclusion: Now we conclude episode number 157, “Urine Testing.” Future doctor Mendoza and Dr. Avila explained when to test your patients to verify their compliance with treatment. Urine tests need to be interpreted wisely. Make sure you establish a good relationship of trust with your patients and rule out other causes for a positive or negative urine test. For example, some patients may be positive for cannabinoids if they are taking certain medications such as PPIs. Dr. Arreaza also reminded us f the recommendation to screen for unhealthy drug use in adults by asking questions, not by testing biological specimens.
This week we thank Hector Arreaza, Janelli Mendoza, and Carol Avila. Audio editing by Adrianne Silva.
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