Phosphatidylethanol (PeTH) testing is a blood test that measures a direct alcohol biomarker, providing insights into an individual’s drinking patterns over an extended period. While known for its accuracy, concerns about false positive results sometimes arise. Understanding the PeTH test and factors leading to such outcomes is important for anyone facing an unexpected positive result.
Understanding PeTH and False Positives
PeTH is a specific direct alcohol biomarker, meaning it forms in the body exclusively when ethanol is present. This distinguishes it from other markers influenced by non-alcohol related factors. PeTH can be detected in whole blood for up to four weeks after alcohol consumption, making it a reliable indicator of recent intake. A common threshold for moderate to heavy alcohol consumption is a PeTH level of 20 ng per mL or higher.
A false positive PeTH result indicates alcohol consumption when an individual has not consumed alcohol, or not enough to trigger a positive result. While PeTH is highly specific to alcohol, the possibility of false positives warrants careful consideration. Research supports PeTH’s high specificity, with some sources indicating over 99% accuracy in detecting alcohol consumption.
Factors Leading to False Positive PeTH Results
Several factors, ranging from laboratory processes to environmental exposures, might contribute to a suspected false positive PeTH result. Errors can occur during sample collection or within the laboratory itself. These include sample mix-ups or mislabeling during collection or processing. Contamination during handling, instrument malfunctions, calibration issues, or errors in data interpretation can also lead to inaccurate readings.
Environmental or incidental exposure to alcohol can also raise questions about PeTH test results. Products such as hand sanitizers, mouthwashes, and certain personal care items contain ethanol. While topical exposure or inhalation from these sources is generally unlikely to produce PeTH levels above common detection thresholds, intense or repeated exposure could theoretically contribute to low-level formation. Ingestion of foods or beverages with trace alcohol content, such as fermented foods or certain non-alcoholic beers, is another potential source of incidental exposure.
While PeTH is known for its specificity, the influence of medical conditions or medications on test results is a topic of ongoing discussion. PeTH test results are generally not affected by factors such as age, gender, or most common medical conditions. However, some very rare medical conditions or specific medications might theoretically interact with the assay or influence PeTH formation or elimination rates, though this is not widely recognized as a common cause of false positives.
Addressing a Suspected False Positive Result
If an individual suspects a PeTH test result is a false positive, proactive steps are important. Consulting medical professionals, the testing facility, or a legal professional can provide guidance on the next course of action. These experts can help interpret the results within the context of an individual’s history and potential exposures.
Requesting further testing, such as a re-test or a confirmatory test using a different method or laboratory, is a common step. Providing comprehensive context and history to the professionals involved is important. This includes openly discussing any potential incidental exposures to alcohol-containing products or relevant medical conditions pertinent to the test results. Understanding the specific cut-off levels used for interpretation can also be helpful.