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What Blood Tests Show Alcohol Abuse?
Detecting alcohol consumption through blood tests is a go-to method in care proceedings and family law settings when assessing a person's drinking trends. Testing alcohol this way paints a picture of whether a person is sober, drinks socially, or is a chronic excessive drinker.
Historically, methods like the Carbohydrate-Deficient Transferrin (CDT) test, Liver Function Tests (LFTs), and Mean Corpuscular/Cell Volume (MCV) analysis have been employed as blood tests for alcohol abuse. However, at AttoLife, we’ve seen a positive shift away from CDT, LFTs, and MCV towards Phosphatidylethanol (PEth) testing. Let’s explore why CDT and similar tests were used, their limitations, and how PEth testing represents a significant step forward for blood test results for alcohol abuse.
What Is a CDT Blood Test?
Indirect biomarkers, such as CDT, LFT, and MCV, were developed to detect the physiological effects of alcohol on the body rather than alcohol itself. This means these blood tests for alcohol abuse measure the outputs of a process, rather than the ethanol directly (aka alcohol). For instance:
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CDT (Carbohydrate-Deficient Transferrin): Measures changes in a glycoprotein due to prolonged heavy alcohol consumption, making it useful for identifying chronic drinkers.
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Liver Function Tests (LFTs): Track enzymes like gamma-glutamyl transferase (GGT) and transaminases such as aspartate transaminase (AST) and alanine transaminase (ALT), which can rise due to liver stress from alcohol abuse.
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MCV (Mean Corpuscular Volume): Detects enlarged red blood cells, a condition often linked to excessive alcohol intake over time.
By collecting a tube of blood through venipuncture, these tests were valuable because they allowed clinicians to infer alcohol consumption indirectly by observing its impact on organ systems and biochemistry.
Yet, the keen observer might spot some issues here:
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Firstly, CDT, LFTs, and MCV are more skewed towards detecting excessive alcohol consumption.
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Secondly, factors other than alcohol could affect these results.
The Flaws of Indirect Biomarkers
Indirect biomarkers for blood tests for alcohol abuse are susceptible to... well, "alcohol abuse." If a "chromic excessive" alcohol drinker has been drinking their whole like, this is a strong possibility their body and metabolic processes will be compromised. However, there are other factors too.
- External Influences: Factors like smoking, medication, vitamin deficiencies, and chronic diseases can affect the results. For example, GGT levels can rise due to medications, and MCV can increase due to vitamin B12 or folate deficiencies.
- Gender and Hormonal Variations: CDT levels can vary between men and women, as well as fluctuate due to hormonal changes, reducing reliability.
- Lifetime Drinking Habits: Chronic alcohol consumption over a lifetime may blunt the expected changes in CDT and LFT levels, making them less effective for detecting recent drinking.
- Limited Detection Window: CDT is most effective for detecting sustained heavy drinking over a few weeks but is less reliable for identifying moderate or recent alcohol use.
- Interferences from Health Conditions: Liver disease, diabetes, cancer, and metabolic disorders can alter CDT, LFT and MCV levels, confounding test interpretations.
The New Way to Test Blood Alcohol: PEth Testing
Phosphatidylethanol (PEth) testing is a breakthrough in alcohol biomarker research. Unlike indirect markers, PEth is a direct biomarker formed only in the presence of ethanol. When alcohol is consumed, PEth is produced in the blood, providing a clear and direct measure of alcohol intake.
Why PEth Testing Is Superior
PEth testing offers several advantages over traditional methods:
High Specificity: PEth is unaffected by external factors like smoking, diet, or chronic conditions, making it a more reliable indicator of alcohol consumption.
Sensitivity: Unlike the old markers of CDT, MCV, and LFTs that are biased towards detecting heavy and prolonged drinking, PEth can detect alcohol intake even at low levels, with a detection window of up to three to four weeks. This makes it a strong blood test for alcohol abuse as well as a great test for identifying teetotallers and social drinkers.
Timely Detection: PEth levels rise within an hour of alcohol consumption and peak within a few days, making it effective for both recent and longer-term drinking assessments. Periods of up to 28 days can be explored, depending on the amount of alcohol consumed.
Ease of Use: PEth only requires a drop of blood, which can easily be collected from a finger prick. Samples can be taken in almost any setting and posted to a lab such as AttoLife.
Why Shifting from CDT to PEth Matters
In child law, the demand for accuracy and reliability has never been greater. PEth testing meets these demands by offering a more reliable and sensitive solution than CDT, LFTs, and MCV.
But it doesn’t stop with blood alcohol testing. Many cases combine a hair strand test for alcohol with PEth testing to increase reliability. While hair testing for alcohol is excellent for exploring longer time frames (up to six months), it is subject to external factors: hair bleaching, heat treatments, and alcohol-containing hair sprays can all affect the integrity of a result.
What’s more, hair strand testing for alcohol is unable to examine hair that is not visible outside of the scalp. The most recent two to three weeks of growth lie hidden from sight under the skin. A single blood alcohol PEth test can look at the most recent month of drinking, while multiple blood alcohol PEth tests can offer a reliable additional marker in case EtG and EtPa are compromised through bleaching, heat, or sprays.
Wrapping Up on CDT and Blood Tests for Alcohol Abuse
While CDT, LFT, and MCV tests played a vital role in the history of alcohol testing, their limitations highlight the need for more reliable methods. CDT, LFT, and MCV can only be used to test for chronic excessive consumption of alcohol over a few weeks. On the other hand, PEth blood alcohol test can be used to test for several hypotheses such as complete abstinence (teetotalism), excessive drinking (including binge drinking), and alcohol social moderate consumption for up to 1 month.
We embrace PEth testing as it represents the future, legal professionals with an accurate and specific tool for detecting alcohol consumption, beyond the historic blood tests for alcohol abuse.
In conclusion, there can be no doubt when answering the question, "Does alcohol show up in a blood test?" However, by moving beyond the indirect markers of the past, PEth testing offers a clearer and more dependable path forward for addressing today’s alcohol testing challenges.