Carbohydrate deficient transferrin
Encyclopedia
Carbohydrate-deficient transferrin (CDT) is a laboratory test used to help detect heavy ethanol
consumption.
Carbohydrate-deficient transferrin is elevated in the blood of heavy alcoholism but raised levels can also be found in a number of medical conditions.
Transferrin
is a plasma protein that carries iron through 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
.
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
.
CDT is measured by taking a sample of a patient's blood. Apparently healthy individuals with no or low reported alcohol consumption and a negative Alcohol Use Disorder Identification Test will have a %CDT <3.0 (95th percentile for the social drinking population). Elevated levels of CDT suggest recent alcohol abuse, especially if other liver-associated enzymes (such as γGT) are elevated. Although recent heavy alcohol use is most commonly associated with elevated CDT, certain rare liver disorders can also increase levels of CDT.
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
consumption.
Carbohydrate-deficient transferrin is elevated in the blood of heavy alcoholism but raised levels can also be found in a number of medical conditions.
Transferrin
Transferrin
Transferrins are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. In humans, it is encoded by the TF gene.Transferrin is a glycoprotein that binds iron very tightly but reversibly...
is a plasma protein that carries iron through 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
Polysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
chains. These polysaccharide chains are branched with sialic acid
Sialic acid
Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid...
residues. Sialic acid is a monosaccharide
Monosaccharide
Monosaccharides are the most basic units of biologically important carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose , fructose , galactose, xylose...
carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
.
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
Alcoholism
Alcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
.
CDT is measured by taking a sample of a patient's blood. Apparently healthy individuals with no or low reported alcohol consumption and a negative Alcohol Use Disorder Identification Test will have a %CDT <3.0 (95th percentile for the social drinking population). Elevated levels of CDT suggest recent alcohol abuse, especially if other liver-associated enzymes (such as γGT) are elevated. Although recent heavy alcohol use is most commonly associated with elevated CDT, certain rare liver disorders can also increase levels of CDT.