Detecting Harmful Alcohol Consumption with a CDT Blood Test

Healthcare providers use various methods to assess alcohol consumption in patients, including brief screenings, blood alcohol concentration (BAC) testing, and carbohydrate-deficient transferrin (CDT) testing. While brief screenings depend on patient honesty and BAC tests measure current alcohol levels, CDT testing relies on biomarkers to identify harmful alcohol use over an extended period.

Understanding Heavy Drinking

The Centers for Disease Control and Prevention (CDC) define heavy drinking as consuming at least 15 drinks per week for men and eight drinks per week for women. It's essential to note that heavy drinking can occur even if a person does not meet the criteria for alcohol use disorder, which is a chronic brain disease affecting daily life.

What Is a CDT Blood Test?

CDT is a substance that carries iron to the bone marrow, liver, and spleen. The CDT blood test measures the level of CDT in the bloodstream. Heavy drinking increases CDT levels, enabling its detection in a blood sample.

How the CDT Test Works

People who drink in moderation or abstain from alcohol generally have lower CDT levels than heavy drinkers. A cutoff of 1.7% CDT in the blood is commonly used to distinguish moderate drinkers from heavy drinkers. Heavy drinkers, defined as those consuming four or more drinks daily for at least five days a week over two weeks, typically exhibit significantly higher CDT levels.

The CDT test provides a highly accurate assessment of heavy drinking and offers insights into long-term alcohol consumption patterns. CDT levels return to normal within two to four weeks after a person stops drinking, and they rise again if drinking resumes after a few days.

When and Why CDT Is Tested

CDT testing is useful in various scenarios beyond routine alcohol screenings. It can be beneficial in the following situations:

Patient Dishonesty: CDT testing can help identify patients who minimize their alcohol consumption during traditional brief screenings. Elevated CDT levels may prompt further investigation into actual drinking habits.

Medical Conditions: CDT testing is crucial for detecting excessive alcohol consumption in individuals with underlying medical conditions where alcohol consumption can be harmful. Conditions like diabetes, high blood pressure, HIV, and liver disease are examples where alcohol consumption can exacerbate symptoms and worsen the condition. Studies indicate that a substantial proportion of patients with these conditions may be consuming alcohol at levels that could lead to complications. CDT testing can help healthcare providers identify these individuals and reduce associated healthcare costs.

Drug Interactions: Alcohol use can interact with various prescription and over-the-counter medications, potentially leading to adverse reactions. Alcohol consumption can intensify the effects of sedatives, sleep aids, and opioid painkillers. CDT testing can help healthcare providers determine if alcohol consumption is contributing to adverse reactions in patients taking these medications.

Recovery Monitoring: CDT testing assists healthcare providers in monitoring abstinence and relapse in patients with alcohol use disorder. Its sensitivity allows for early detection of increases or decreases in alcohol consumption, and it can be used by psychotherapists and medical professionals to adjust treatment plans accordingly.