Carbohydrate deficient transferrin (CDT) can be used to assess a patient's chronic alcohol consumption. The test does not correlate with the amount of alcohol consumed, but relates to the prolonged consumption of large quantities of alcohol. A single episode of heavy drinking will not elevate CDT levels.
CDT is reported as a percentage of total transferrin to reduce the effects of gender and varying transferrin concentrations.
CDT has a long half-life of 15 days. Under conditions of total abstinence it may take 1-2 months for CDT levels to return to normal.
The most reliable interpretation is obtained with a series of CDT tests to detect trends, with the tests being performed at 1-2 month intervals to allow for the long half-life of this protein.
False positive CDT results may occur in patients with severe liver disease, autoimmune hepatitis, biliary cirrhosis, liver cell cancer, haemochromatosis, transferrin variants and rarely congenital disorders of glycosylation.
PLASMA samples are not acceptable - presence of fibrinogen causes interference.
Chilled (2 - 8 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)
Chronic alcoholism causes a transient change in the glycosylation pattern of transferrin where the relative amount of disialo transferrin (carbohydrate deficient transferrin: CDT) is increased.
CDT typically normalizes within several weeks of abstinence of alcohol use. However, it is important to recognize that there are other causes of abnormal CDT levels, which include congenital disorders of glycosylation and other genetic and nongenetic causes of acute or chronic liver disease.
CDT testing alone is not recommended for general screening for alcoholism; however, when combined with other methods (ie, gamma-glutamyltransferase, mean corpuscular volume, patient self-reporting, ethylglucuronide analysis), clinicians can expect to identify the majority of patients who consume a large amount of alcohol.
|Reference Interval CDT-IFCC||Classification|
|< 1.8 %||Normal result|
|1.8 – 2.0 %||Inconclusive|
|> 2.0 %||Positive result|
Measurement uncertainty 10 %
CDT-IFCC by Capillary Electrophoresis
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