From the Guidelines
Carbohydrate-Deficient Transferrin (CDT) is not a reliable biomarker for detecting alcohol consumption due to its low sensitivity and specificity, and its use is not recommended for systematic screening of alcohol misuse.
Definition and Mechanism
CDT refers to forms of the iron-carrying protein transferrin that have reduced carbohydrate content, which increases in the bloodstream when a person regularly consumes significant amounts of alcohol. The biological mechanism involves alcohol interfering with the glycosylation process of transferrin in the liver, resulting in these carbohydrate-deficient variants 1.
Limitations and Recommendations
However, the utility of CDT is limited by its low sensitivity of 25%-50% in several studies and by false-positive results arising in patients with severe liver disease in the absence of alcohol use 1. The most recent and highest quality study recommends that biomarkers, including CDT, are not required in the systematic detection of alcohol misuse, and their use should not be a substitute for a medical interview 1.
Clinical Use
Instead, questionnaires such as the AUDIT are more effective than biochemical tests, including CDT, for detecting alcohol misuse 1. CDT testing may still be useful on a case-by-case basis, particularly when used in conjunction with other markers like gamma-glutamyl transferase (GGT) to monitor alcohol use in treatment programs or assess compliance with sobriety 1.
Key Points
- CDT has low sensitivity and specificity for detecting alcohol consumption
- Its use is not recommended for systematic screening of alcohol misuse
- Questionnaires such as the AUDIT are more effective for detecting alcohol misuse
- CDT testing may still be useful on a case-by-case basis, particularly when used in conjunction with other markers.
From the Research
Definition and Purpose of CDT
- Carbohydrate-Deficient Transferrin (CDT) is a biomarker used to detect and monitor heavy alcohol consumption 2, 3, 4, 5, 6.
- CDT is considered the most specific serum biomarker of heavy alcohol consumption, defined as ≥ 350-420 g alcohol/week 2.
Factors Affecting CDT Levels
- Several factors can affect CDT levels, including:
- Alcohol use: CDT levels are affected by alcohol consumption, with higher levels indicating heavier drinking 2, 3, 4, 5, 6.
- Genetic factors: Genetic variants can influence CDT levels 4.
- Liver disease: End-stage liver disease can affect CDT levels 4, 5.
- Gender: Women may produce more CDT under natural conditions and less CDT in response to heavy drinking 3, 4, 6.
- Age: Age may be a confounding factor, but its effect on CDT levels is not clear 4.
- Medication: Certain medications, such as estrogen and anticonvulsants, can affect CDT levels 4.
Clinical Applications of CDT
- CDT can be used to:
- CDT can be used in combination with other biomarkers, such as gamma-glutamyltransferase (GGT), to enhance the sensitivity of detection of heavy alcohol consumption 3, 6.
Limitations of CDT
- CDT has limited sensitivity as a biomarker of heavy alcohol consumption, particularly in women, patients with cirrhosis, and those with an elevated body mass index (BMI) 2.
- CDT values can be influenced by various factors, including medication, liver disease, and genetic variants, which can lead to false positives or false negatives 4.