Carbohydrate Deficient Transferrin (CDT) in Serum
This test measures a form of transferrin protein that has lost some of its sugar molecules, which can help detect long-term alcohol misuse.
["CDT helps identify heavy alcohol consumption over time."]
Key facts at a glance
- LOINC
- 50337-5
- Short code
- CARBAMET
- Synonyms
- Carbmzpn + Metab Pnl SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 4
- Ref high
- 12
- Critical range
- — – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 1–99 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Immunoassay
- CPT
- 80156
- SNOMED
- 395081000
- Specimen volume
- 1-2 mL of serum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test if you have symptoms of alcohol-related liver damage, unexplained liver issues, or if you’re suspected of chronic alcohol abuse. It’s often used alongside other tests to confirm or rule out alcohol dependence.
How Is the Test Performed?
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum, which is then analyzed for CDT levels using an immunoassay method.
What Do Results Mean?
Elevated CDT levels suggest chronic alcohol exposure, but results alone aren’t diagnostic. They’re typically interpreted alongside clinical findings, other tests (like liver function tests), and patient history.
What Are Common Causes of Abnormal Results?
While alcohol misuse is the primary cause, other factors like certain medications, pregnancy, or genetic conditions may also affect CDT levels. Your provider will consider all possible causes.
Reference range
Therapeutic range: 4-12 µg/mL for carbamazepine (parent drug); 10,11-epoxide metabolite typically reported separately. Toxic: >15 µg/mLN/A
No special preparation required. Trough levels should be drawn immediately before the next scheduled dose, typically in the morning. Consistent timing of collection relative to dosing is essential for accurate therapeutic drug monitoring.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CDT in Alcohol Use Disorders
Short name
CDT (Serum)
Frequently asked questions
What does a high CDT level indicate?
How long does it take to see results?
Can I drink alcohol before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 10, 2026. · Read our editorial policy