Detecting Alcohol Biomarkers in Urine, with Dr. Kamisha Johnson-Davis, PhD
In a climate of rampant substance abuse, screening measures are susceptible to human error and device malfunction, which can lead to slowed laboratory practice.
Goals of Clinical Assessment and Diagnosis
Reduce Turnaround Time
Reducing turnaround time is a goal shared across all lab sites. One preemptive measure against extended turnaround time is collecting a sufficient sample. When adequate sample quantity is obtained, confirmatory testing can be performed in the event of a presumptive positive result through an assay screen.
Efficient Specimen Shipping
Specimen shipping and handling is another weighty factor for laboratories to consider. Samples must be stored within a specific temperature range, and they need to be transported with care; otherwise, sample integrity will be compromised, which invalidates the clinician’s test order.
Each day, laboratories focus on eliminating, or at least minimizing, the impact of variables in drug abuse screening. Investments are made in clinical research to discover new ways to preserve specimen integrity without increasing specimen handling.
Diagnosing Exposure to Alcohol
As an Associate Professor in the Department of Pathology at the University of Utah, and a Medical Director for Clinical Toxicology at ARUP Laboratories, Kamisha Johnson-Davis, PhD, examines reliable biomarkers of alcohol exposure to provide clinicians with consistently accurate results.
Quantifying ethanol in whole blood, serum/plasma or urine testing can be limited by detection windows under 24 hours.
There are two primary alcohol metabolites which are identifiable in urine following alcohol consumption that can provide a window of detection up to 80 hours after use:
- EtG, or Ethyl Glucuronide
- EtS, or Ethyl Sulfate
EtG and EtS are direct biomarkers of alcohol use. According to Dr. Johnson-Davis,
“EtS may be considered a more specific and reliable biomarker of alcohol ingestion in comparison to EtG because EtS is not increased (>100 ng/mL in urine) from hand sanitizer exposure. In addition, the glucuronide molecule in EtG can be cleaved by bacteria, for example, in patients with urinary tract infections. This can lead to false negative results, especially if samples are not stored at appropriate temperatures.”
Determining which alcohol marker to test for to evaluate alcohol exposure depends on the scenario. “When clinicians prescribe medications for pain management, they also want to know if their patients are consuming alcohol while taking these medications. The clinician can order a EtG urine screen by Immunoassay, or they have the option to order a confirmatory test by Mass Spectrometry (MS).”
Dr. Johnson-Davis emphasizes the need to provide clinicians with testing options. Whenever new methods are adopted, the laboratory must perform a thorough validation to create robust, precise and accurate protocol.
Kamisha Johnson-Davis began her career with a PhD in Pharmacology from the University of Utah, where she later completed a postdoctoral fellowship in Clinical Chemistry. She is now a diplomat of the American Board of Clinical Chemistry and a preeminent industry role model.