Carbohydrate Deficient Transferrin
Label Mnemonic: CDT
Epic Lab Code: LAB2793
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Specimen Instructions:
Draw blood in a plain red-top tube. Note: This test is for evaluation of alcohol abuse. Patient's age is required on request form for processing.
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
0.1 mL of serum
Delivery Instructions:
Submit specimen to laboratory as soon as possible after collection.
Turn Around Time:
5-10 days upon receipt at reference laboratory
Reference Range:
< or = 0.10
0.11 - 0.12 (indeterminate)
Interpretive Data:
Patients with chronic alcoholism may develop abnormally glycosylated transferrin isoforms (ie, CDT >0.12). CDT results from 0.11 to 0.12 are considered indeterminate.

Patients with liver disease due to genetic or nongenetic causes may also have abnormal results.
Comments:
Chronic alcoholism causes a transient change in the glycosylation pattern of transferrin where the relative amounts of disialo- and asialotransferrin (carbohydrate deficient transferrin [CDT]) are increased over the amount of normally glycosylated tetrasialotransferrin. This recognition led to the use of CDT in serum as marker for chronic alcohol abuse. 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 (CDG) 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 [GGT], mean corpuscular volume [MCV], patient self-reporting) clinicians can expect to identify 90% or more of heavily drinking patients.

This assay has not been fully validated for the investigation of alcoholism.

CDT testing alone is not recommended for general screening for alcoholism.

The abnormal transferrin isoform pattern in patients with chronic alcoholism is similar to that observed in CDGS. However, unlike most patients with CDG, the relative amount of mono-glycosylated transferrin is much lower. Other conditions such as hereditary fructose intolerance, galactosemia, and liver disease may result in increased levels of CDT.
Methodology:
Affinity Chromatography/Mass Spectrometry (MS)
CPT Code:
82373