Carbohydrate Deficient Transferrin (CDT) Blood Test

This private blood test measures percentage carbohydrate-deficient transferrin (%CDT), the standard blood biomarker used to assess sustained heavy alcohol intake over the previous 2 to 4 weeks. The catalogue test price is £209.38 plus a £50 phlebotomy fee, with results in 3 days.

CDT is widely requested for medical assessments, occupational health reviews and fitness-to-drive preparation before DVLA medical examinations.

Written by Mr Stephen Lingam. Reviewed by Dr Mohammad Bakhtiar (GMC 4694470) on 18/10/2026.

How long does it take for CDT levels to normalise after stopping alcohol?

CDT has a biological half-life of about 10 to 14 days, so elevated levels usually take 3 to 4 weeks of abstinence to return to the normal range.

Will a single social drink raise my CDT result?

No. CDT responds to sustained heavier drinking over a period of a week or more rather than an isolated single drink.

Do I need to fast before a CDT blood test?

No fasting is required before your appointment at 117a Harley Street.

Should I book CDT alone or with PEth and liver function tests?

If you also want PEth, liver enzymes and MCV in one appointment, our Alcohol Profile (£261.25 plus £50 blood draw) includes CDT alongside all four markers.