CDT differs from the glycoproteine Transferrine, which is responsible for iron transport through the cell membrane, by missing Sialine Acid substituents (Disialo-, Monosialo- and Asilalo-Transferrine), whose transmission takes place via the enzyme glycosyltransferase, whose activity is however strongly decreased in cases of chronic consumption of alcohol.
Consequently the CDT concentration rises strongly (normal value male approx. 20 U/l, female 26 U/l, increased from 30 up to >60 U/l).
Recently the proportional portion of the CDT in relation to the entire Transferrine is used as relative unit. The analysis takes place with a %CDT Immunoassay (e.g. company BIO RAD) or by means of HPLC. Normal values are below 3% (BIO RAD test: under 2,6%). If the daily consumption of alcohol of men is over 60 g/day over at least 3 weeks or with women over 50 g/day over 2 weeks, a CDT portion of up to 18% can be achieved.
Carbohydrate Deficient Transferrine is a sensitive and specific marker (90%) for alcohol abuse, which is increased after absinence still for a longer period (half-life 14-17 days), normal values are reached after approximately 2-4 weeks of abstinence.
The determination of the CDT value is indicated in the following cases: