alcohol. It is possible to achieve very high alcohol levels in the urine providing that all conditions for fermentation of glucose are satisfied. Urine alcohol concentrations do not
directly correlate to blood alcohol con- centrations. Te standard conversion rate is that urine alcohol is 1.3 times higher than the blood alcohol provided that the sample was properly collected (i.e. first void is not used) and that the stomach has completed absorption of the alcohol. Caution must be exercised in evaluating
urine alcohol results in assessing impair- ment and should only be done with a blood or breath alcohol
test.Determining whether the donor of the sample was im- paired at the time of collection cannot be confirmed by a urine alcohol test based on collection procedures used for workplace drug testing samples.
Advanced Laboratory Alcohol Biomarkers More advanced techniques such as LC/ MS/MS are used for the newer direct biomarkers and can be used by clinicians in evaluating the donor or patient for alcohol abuse. Te most sensitive marker of recent
alcohol use is Ethyl Glucuronide (EtG) and Ethyl Sulfate (EtS). Tese two alcohol metabolites are primarily measured in the urine but can also be measured in other biological specimens, including hair. Both metabolites are quickly found in the urine and can reach quantitation of several thousands of nanograms per milliliter (ng/ mL) of urine within 2–4 hours and will be found for 1–2 days following low consump- tion of alcohol. Primary analytical methods have been liquid chromatography with tandem mass spectrometry. Since alcohol is found in many products, from OTCs (e.g. mouth wash, cough syrups, alcohol-gel hand sanitizers), liquid prescription drugs, aerosols (e.g. hair spray, inhalers), food preparations (e.g. alcohol based flavorings),
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the source for the positive EtG/EtS result can be difficult to isolate. It is common to use this test in the monitoring of alcohol abstinence in individuals who have had a history of alcohol abuse, are in rehabilita- tion to maintain a professional license (e.g. doctors, nurses, pharmacists, atorneys), maintain an automobile license, or moni- toring of under aged drinking2
. One of the newest biomarkers is Faty
Acid Ethyl Esters (FAEE). FAEE’s are formed during non-oxidative metabolism of ethanol by the conjugation of ethanol to endogenous free faty acids and faty-acid acyl-CoA. Tey can be detected in hair, meconium, skin surface lipids, and blood. Several studies have been performed to correlate the concentrations of FAEE with increasing alcohol use. Detection is delayed from 1–2 weeks following high alcohol consumption3
research and clinical evaluations. Phosphatidylethanol (PEth) is another
indicator of alcohol consumption which is formed primarily in erythrocytes with a mean half-life of approximately 4 days in blood. PEth is an ethanol-derived phospholipid formed from phosphati- dylcholine (PC) in cell membranes by transphosphatidylation reaction cata- lyzed by phospholipase D. Phospholipase D normally hydrolyzes PC into phospha- tidic acid and choline but has a greater than 1000 fold higher affinity for ethanol than water. Because of the higher affinity, PEth is formed rather than the normal phosphatidic acid4
. Te value that PEth brings to the clini-
cian is that there appears to be no false positive test results, and it provides a clear interpretation of alcohol use. Storage con- ditions of the blood for PEth are extreme- ly important. Blood levels are not affected aſter 72 hours of being refrigerated.
Summary Interpreting urine alcohol concentrations for employment purposes is difficult
without other collaborating evidence, such as the smell of alcohol on the indi- vidual or reasonable cause due to perfor- mance issues. Negative results indicate that the individual has not ingested alcohol within the last eight hours but a positive result requires further investiga- tion and should not be the lone reason for disciplinary actions. The analytical laboratory that uses
mass spectrometry is playing a signifi- cant role in the diagnosis and subse- quent treatments involved in alcohol abuse. The direct markers, such as EtG/ EtS, have short detection windows and extreme sensitivity to recent alcohol use. The new biomarkers, such as FAEE and PEth can lengthen the window of detec- tion to 30 days and offer further insight into alcohol abuse. ❚
. Teir use has been primarily References 1
Gonzales K, et. al. Alcohol-Attributable Deaths and Years of Potential Life Lost –11 States, 2006-2010. Morbidity and Mortality Weekly Report. 63(10);213-216.
2
Laposata M. Fatty acid ethyl esters:short-term and long-term serum markers of ethanol intake. Clin Chem 1997;43:1527-34.
3
Kuntz D. Use and application increase for new alcohol markers. CFTN June 2009: 2-4.
4
Gnann H, Weinmann W, Thierauf. Formation of phosphatidylethanol and its subsequent elimination during an extensive drinking experiment over 5 days. Alcohol Clin Exp Res 2012;36:9: 1507-1511.
David Kuntz, PhD, is the Executive Director for Analytical Toxicology at Clinical Reference Laboratory in Lenexa, Kansas. Dr. Kuntz is Co-Responsible Person for the SAMHSA labo-
ratory and the College of American Pathologists (CAP) forensic drug testing Scientific Director. He holds a laboratory director license in a number of states and is an inspector for SAMHSA and CAP forensic programs. Dr. Kuntz is a Board Certified Toxicologist and is a national expert in urine adulteration and drug detection in urine, oral fluid, and sweat using GC/MS and LC/MS/MS. Dr. Kuntz has worked in workplace drug testing for the past 24 years and has testified extensively regarding drug use, interpretation, and adultera- tion of urine, oral fluid and sweat samples.
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