Carbohydrate-Deficient Transferrin (CDT)

Carbohydrate-deficient transferrin (CDT) is a laboratory test used to help detect heavy ethanol consumption.

Transferrin is a plasma protein that carries iron though the bloodstream to the bone marrow, where red blood cells are manufactured, as well as to the liver and spleen. Structurally, transferrin is a polypeptide with two N-linked polysaccharide chains. These polysaccharide chains are branched with sialic acid residues. Sialic acid is a monosaccharide carbohydrate. Transferrin is a plasma protein for iron ion delivery. ... Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... Sialic acid Sialic acid is a derivative of a nine-carbon monosaccharide, named from the Greek σιαλοσ (sialos) saliva. It is the negative charge of this chemical that is responsible for the slippery feel of saliva and mucins coating the body’s organs. ... Carbohydrates are chemical compounds that contain oxygen, hydrogen, and carbon atoms, and no other elements. ...

Various forms of transferrin exist, with differing levels of sialylation. The most common form is tetrasialotransferrin, with four sialic acid chains. In persons who consume significant quantities of alcohol (usually more than 4 or 5 alcoholic beverages a day for two weeks or more), the proportion of transferrin with zero, one, or two sialic acid chains is increased. These are referred to as carbohydrate-deficient transferrins. These carbohydrate-deficient transferrins can be measured in the bloodstream, and are an important marker for alcohol abuse. Used with other tests, such as gamma glutamyl transferase (GGT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), carbohydrate-deficient transferrin can be a useful tool in identifying problem drinking, such as alcohol abuse or alcoholism. Gamma glutamyl transferase (GGT or GGTP, or Gamma-GT) (EC 2. ... Aspartate transaminase (AST) also called Serum Glutamic Oxaloacetic Transaminase (SGOT) or aspartate aminotransferase (ASAT) (EC 2. ... Alanine transaminase or ALT is (mostly) a liver enzyme (EC 2. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ...

CDT is measured by taking a sample of a patient's blood. Normally, CDT comprises less than 2% of all transferrins circulating in the bloodstream. Elevated levels of CDT suggest recent alcohol abuse, especially if other liver-associated enzymes (such as GGT) are elevated. Although recent heavy alcohol use is most commonly associated with elevated CDT, certain rare liver disorders can also increase levels of CDT.