What it measures
Transferrin is the protein that carries iron in the blood. CDT is a form of it with fewer sugar chains attached, and its share rises after a sustained period of heavy drinking. The result is given as a percentage of all transferrin.
Why people test it
- Used as a marker of sustained heavy drinking over the previous few weeks.
- Asked for in some workplace, driving licence and legal assessments of alcohol use.
- Measured to help tell whether raised liver results are linked to alcohol or another cause.
- Repeated over time to follow a change in drinking.
Typical range
Labs report CDT as a percentage of all transferrin. Ranges and cut-offs vary by lab, method, age and sex, and your report shows the lab's own range.
Finger-prick or vein?
Usually sold as a home finger-prick kit. It can also be measured on a vein sample.