Carbohydrate-deficient transferrin - serum

5 mL blood in plain tube.

Method dependent.

This is the most reliable laboratory method for the diagnosis of alcoholism, in cases where the usual laboratory features (eg, increased GGT, red cell macrocytosis) are unnhelpful.
Patients who have been drinking >50 g alcohol per day for several weeks show an increase in carbohydrate-deficient transferrin, although the test sensitivity is only approximately 50%; that is, a negative result does not exclude the possibility of alcohol ingestion.

Patients with a genetic carbohydrate-deficient glycoprotein syndrome show decreased levels and abnormal structure of a number of plasma glycoproteins, including transferrin, haptoglobin, thyroxine-binding globulin, antithrombin III and protein C.