Synonyms: CDT, CARBOHYDRATE-DEFICIENT TRANSFERRIN
Related tests: GGT
Clinical significance
The significant clinical and social effects of alcohol abuse have long made it necessary to replace general tests of liver function and the full blood count with more specific toxicological markers. Carbohydrate-deficient transferrin (CDT) is an extremely sensitive and specific diagnostic marker of chronic alcohol consumption. Transferrin is an iron-transporting glycoprotein made up of a single polypeptide chain with two nitrogen-linked polysaccharide chains. These polysaccharide chains are branched, with terminal sialic acid residues. Human transferrin exists in several isoforms with different degrees of sialylation. There appear to be at least 6 isoforms: penta-, tetra-, tri-, di-, mono- and asialotransferrin, and in a person who does not abuse alcohol the tetrasialo form should predominate. After excessive and prolonged alcohol consumption, on the other hand, there is an increase in the asialo, monosialo and disialo forms.
Clinical indications
Chronic alcohol abuse; monitoring of patients undergoing detoxification.
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes.
Notes
There are genetic variants of transferrin that mask the desialylated glycoforms and prevent accurate measurement of CDT. The HPLC method can distinguish them, avoiding false positive results.
Serum CDT levels generally return to normal after 2-4 weeks of complete abstinence from alcohol.