Carbohydrate Deficient Transferrin (CDT)

Immunology

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Description

Serum transferrin is a glycoprotein which acts as an iron-transporting protein. Human transferrin occurs in isoforms with different levels of sialylation. There are at least six such isoforms: penta, tetra, tri, di, mono and asialyo transferrin. In a normal healthy individual the tetrasialo isoform predominates, but it has been found that in individuals with chronic or recent elevated alcohol intake the asialo, mono and disialo isoforms occur in higher levels. Together, the asialo, mono and disialo isoforms are collectively referred to as carbohydrate-deficient transferrin (CDT). Studies have shown that alcoholics who consume greater than 50g of ethanol/day for at least one week will have an increase in serum CDT levels [5].CDT, unlike ethanol metabolites, remains elevated for a prolonged period after the cessation of drinking, with studies showing that it has a half-life of 15 days [2,5]. In males/females that are in the overweight or obese categories according to BMI, serum CDT is not as good as a marker of excessive alcohol consumption [2]. Interestingly, the test is reportedly less useful in non smokers than smokers [2]. CDT can also be falsely positive (see interpretation). In 1991 studies by Stibler showed that in alcoholics the assay has an overall sensitivity of 82% and a specificity of 97%. It is reportedly superior as a diagnostic test than gamma-glutamyl transferase (yGT), which has a sensitivity of only 58% in heavy drinkers [1]. CDT is it an unsuitable test for screening the general population for short-term increases in alcohol consumption and binge drinking [4].

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Indications

Chronic alcoholism and alcohol avoidance compliance.

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Sample Type

2mL Serum (Gel 5mL Yellow tube).
Requests from outside Sheffield: transport at ambient temperature via Royal Mail or Courier.

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Reference Range

0.0 - 2.6%.

Reference range established by in-house validation of manufacturers information.

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Turnaround Time

Within 10 days

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Testing Frequency

Weekly

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External Notes

Marker of Chronic Alcoholism.

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References

Wolff K, et al. Road safety research report 103: The role of carbohydrate deficient transferrin as an alternative to gamma glutamyl transferase as a biomarker of continuous drinking: A literature review. Department of transport. 2009. [Ref 1].
Whitfield JB, Dy V, Madden PAF et al. Measuring Carbohydrate-Deficient Transferrin by Direct Immunoassay: Factors Affecting Diagnostic Sensitivity for Excessive Alcohol Intake. Clin Chem. 2008. 54: 1158-1165. [Ref 2].
Bortolotti F,De Paoli G,Tagliaro F. Carbohydrate-deficient transferrin (CDT) as a marker of alcohol abuse: a critical review of the literature 2001-2005. Journal of Chromatography B: Analytical Technologies in the Biomedical & Life Sciences. 2006. 841(1-2): 96-109.
Fleming MF, Anton RF, Spies CD. A review of genetic, biological, pharmacological, and clinical factors that affect carbohydrate-deficient transferrin levels. Alcohol Clin Exp Res. 2004. 28:1347-1355. [Ref 3]
Miller PM, Anton RF. Biochemical alcohol screening in primary health care. Addict Behav. 2004. 29:1427-1437.
Golka K, Wiese A. Carbohydrate-deficient transferrin (CDT): a biomarker for long-term alcohol consumption.J Toxicol Environ Health B Crit Rev. 2004. 7:319-337. [Ref 4]
Koch H,Meerkerk GJ,Zaat JO et al. Accuracy of carbohydrate-deficient transferrin in the detection of excessive alcohol consumption: a systematic review. Alcohol & Alcoholism. 2004. 39(2): 75-85.
Sharpe PC. Biochemical detection and monitoring of alcohol abuse and abstinence. Ann Clin Biochem. 2001. 38:652-664. [Ref 5].

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