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Carbohydrate-deficient transferrin (CDT) in serum/plasma

Published: August 9, 2026Updated: August 14, 2026

This test measures a form of transferrin protein that has lost some of its sugar molecules. It helps identify long-term alcohol use or liver problems.

Quick summary

["CDT can spot heavy drinking or liver damage over time."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 14, 2026Editorial policy

Key facts at a glance

LOINC
78434-8
Short code
CBZPNL
Synonyms
Carbmzpn Trgh + Metab Pnl SerPl
Category
chemistry
Sample
serum
Container
Red-top serum collection tube (no anticoagulant) or serum separator tube (SST)
Units
N/A
Ref low
4
Ref high
12
Critical range
2 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
0–99 years
Method
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or High-Performance Liquid Chromatography (HPLC) with UV detection
CPT
80156 (Carbamazepine total); 80157 (Carbamazepine free); additional CPT codes may apply for 10,11-epoxide metabolite
SNOMED
167351002 (Carbamazepine); 387207008 (Carbamazepine-10,11-epoxide); 39579001 (Serum specimen)
Specimen volume
3.0 mL serum minimum; 1.0 mL per analyte for the panel
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles. Centrifuge within 2 hours of collection.
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
24–72 hours
Order
routine

Why This Test Matters

Transferrin is a protein in your blood that carries iron. When your body processes alcohol, it can affect how transferrin is made. Over time, alcohol use can cause some transferrin molecules to become ‘sugar-deficient,’ making CDT detectable in the blood.

What to Expect

You’ll have a small needle inserted into your arm to draw blood. The test checks a sample of your serum or plasma. Results are usually ready within a few days.

How It’s Used

Doctors use CDT to monitor alcohol consumption or liver health, especially in people who drink heavily or have liver-related symptoms.

What the Results Mean

Higher-than-normal CDT levels may suggest chronic alcohol use or liver disease. Your doctor will interpret results in the context of your medical history and other tests.

Reference range

Carbamazepine Total Trough: 4.0-12.0 mcg/mL; Carbamazepine Free Trough: 1.0-3.0 mcg/mL; Carbamazepine-10,11-Epoxide (active metabolite): 0.5-2.0 mcg/mL. Therapeutic ranges may vary by laboratory and clinical context.N/A

Specimen: serum

Trough specimen should be drawn immediately before the next scheduled dose, typically in the morning. No fasting required. Patient should be on a stable carbamazepine dose for at least 5-7 days prior to testing for accurate therapeutic monitoring. Document time of last dose and time of specimen collection on the requisition.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CDT is a biomarker for alcohol-related liver damage and chronic alcohol misuse. It complements other tests like liver enzymes or alcohol metabolite screens, offering a longer-term perspective on alcohol exposure.

Short name

CDT Screening

Frequently asked questions

What causes CDT to rise?
Chronic alcohol consumption is the most common cause, but liver diseases (e.g., hepatitis) or certain medications can also affect CDT levels.
Does CDT replace other alcohol tests?
No. CDT is one tool among many—like urine toxicology screens or liver function tests—to assess alcohol use or liver health. Your doctor may use multiple tests together for a full picture.
Can I lower my CDT levels?
Yes, quitting alcohol or reducing intake can help normalize CDT over time. Liver health also improves with diet, hydration, and avoiding harmful substances.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 14, 2026. · Read our editorial policy