Carbohydrate-deficient Transferrin (CDT), Adult

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Turnaround Time: 3 - 5 days
CPT Code:


Test Type: 1 mL Serum
Stability Time:



Room temperature

2 days


2 days


7 days

Freeze/thaw cycles

Stable x3

Reference Range:

• Normal: <1.4%

• Inconclusive: 1.4% to 1.6%

• Elevated: >1.6%


An indicator of chronic alcohol abuse.

This test is not suitable for the evaluation of patients suspected of having CDG syndrome (congenital disorders of glycosylation), genetic variants of transferrin, some monoclonal component, or high polyclonal increases, liver injuries (cirrhosis due to chronic alcohol abuse, end-stage disease).

CDT testing can be an effective tool for the early diagnosis of chronic alcohol misuse, for the detection of patients addicted to alcohol, and for the follow-up of treatment and diagnosis of alcohol relapse.

CDT quantitation is useful in detecting abusive alcohol consumption (defined as ethanol consumption >40 mL per day for at least two weeks) and a more specific marker for alcohol exposure than other available markers, such as γ-glutamyl transferase (GGT). It enables early detection of alcohol misuses and follow-up of alcoholic patients.

On stopping alcohol consumption, the CDT level goes back to normal after two to four weeks. If the patient starts drinking after withdrawal, CDT increases in a few days.

Transferrin is an 80-kDa serum glycoprotein produced by the liver. Its function is to carry iron around an organism mediated by iron-binding properties. Transferrin comprises a single polypeptide chain with two polysaccharide chains ended by a sialic acid residue. There are several isoforms of human transferrin with different levels of sialylation. Carbohydrate-deficient transferrin (CDT), defined by 2 sialo and 0 sialo isoforms, is a marker of chronic alcohol abuse.

Collection Details:

Collection Instructions:

This test is intended for evaluation of alcohol abuse. To evaluate patients for congenital disorders, physicians should contact LabCorp customer service.

Red-top tube or gel-barrier tube.

Serum should be separated from cells within two hours of venipuncture. Send serum frozen in a plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.