Amadeo Pesce (Presenter)
Precision Diagnostics
Authorship: Amadeo Pesce, Kevin Krock, Richard Thomas, Joyce Nickley, Agnes Cua, Josh Corbin
Precision Diagnostics LLC San Diego CA
| Short Abstract Current LC-MS/MS technology allows for quantitation of ethyl sulfate down to concentrations of 100ng/mL. Interpretation of the most appropriate cutoff is complicated by incidental or environmental exposure. Using a previously described frequency distribution model of log concentration versus observed number to determine cutoff values for many drugs shows that concentrations of Ets below 500ng/mL are most likely due to environmental or incidental exposure. |
Long Abstract
Introduction
Alcohol use disorder is a major health problem. To identify, monitor and treat patients with this affliction biomarkers are used. They are physiological indicators of alcohol exposure or ingestion and reflect the use of chronic and/or high levels of alcohol. Properly used they provide objective evidence of alcohol use. Two of these biomarkers are ethyl glucuronide (Etg) and ethyl sulfate (Ets) (1).
Current LC-MS/MS technology allows for quantitation of ethyl sulfate down to concentrations of 100ng/mL. Interpretation of the most appropriate cutoff is complicated by incidental or environmental exposure. We have used a frequency distribution model to determine cutoff values for many drugs (2). We examined our database of patient specimens to establish the most appropriate cutoff for Ets.
Methods
Patient population
This was a retrospective study of convenience patient specimens from pain practices and rehabilitation facilities. The study was approved by Aspire IRB, Santee California.
Analytical method
Ets was measured using a quaternary plumbed Thermo Fisher TSQ Endura in the negative ion mode with heated electrospray ionization (HESI). The run time was 3.98 minutes. For Ets the precursor ion was selected to be 125 amu, the collision energy at 32.5 volts and the product ions were selected to be 80.1 and 97.1 amu. The internal standard was Ets d5. The cutoff was set at 100ng/mL for Ets
Results
We tested 63,000 specimens and plotted all those above our 100ng/mL lower limit of quantitation. The right side of the frequency distribution curve roughly followed a bell-shaped pattern. At the low end of the observed concentration, (the left side of the curve), there was an increased frequency of positive results. That is the curve did not follow the expected Gaussian distribution. In fact, the lower the observed concentration the greater its frequency. This suggested that Ets concentrations below 500ng/mL are also most likely from incidental sources.
Discussion
We have previously shown that for most drugs the urinary excretion pattern plotted using a frequency distribution curve versus concentration expressed as a logarithmic function results in a bell-shaped curve (2). However, for Ets analyte, the right side of the curve follows the expected bell shaped pattern, but the left side of the curve sharply deviated from the expected pattern. That is, the frequency of specimens positive for Ets increased. This cannot be explained as the drug coming from a single dose. We argue that the increased number of observed low concentrations of Ets are coming from an additional source which we term incidental exposure. It appears that this incidental exposure is a major cause of the observed values below 500ng/mL. These findings agree with the recommendations of Reisfield et al (3).
“An EtG and EtS threshold of at least 500 ng/mL is adequate to distinguish between intentional ethanol use and incidental exposure caused by intensive use of high alcohol content mouthwash. Use of a threshold at 100 or 200 ng/mL has a potential for false-positive results in patients who regularly use mouthwash”.
Conclusions. Being able to identify very low concentrations of ETS accurately by LC-MS/MS does not necessarily offer a clear clinical answer to the question of consumption. Such data needs to be used in conjunction with other patient information/history. Observed concentrations of ETS below 500 ng/mL can be due to environmental or incidental exposure. Some of the observed concentrations of Ets below 500ng/mL are likely due to environmental or incidental exposure.
References & Acknowledgements:
1. A. Helander and O. Beck. Ethyl sulfate: a metabolite of ethanol in humans and a potential biomarker of acute alcohol intake. J. Anal. Toxicol. 29: 270–274 (2005).
2. Pesce, A., West,C., West,R; Crews,B, Mikel C., Almazan,P., Latyshev, S; Rosenthal, M.,Horn, P Reference intervals: A novel approach to detect drug abuse in a pain patient population J. Opioid Management 2010; 6: 341-350
3. Reisfield GM, Goldberger BA Crews B . Pesce AJ.Wilson GR, Teitelbaum SA, and Bertholf RL Ethyl Glucuronide, Ethyl Sulfate, and Ethanol in Urine after Intensive Exposure to High Ethanol Content Mouthwash Journal of Analytical Toxicology, 2011; 35: 264-268
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| Salary | yes | Precision Diagnostics LLC |
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| Expenses | yes | Precision Diagnostics LLC |
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