CDT Blood Test | London Blood Tests UK

Assess chronic alcohol consumption with our CDT blood test for £168. UKAS-accredited analysis, objective alcohol marker, optional GP consultation.

The Carbohydrate Deficient Transferrin (CDT) Blood Test measures specific transferrin isoforms altered by sustained alcohol intake, making it a highly specific biomarker for chronic alcohol consumption. Available for £168, analysed in a UKAS-accredited laboratory, with results typically available within 5–7 business days and an optional GP consultation for interpretation.

What is a Carbohydrate Deficient Transferrin (CDT) Test?

Transferrin is a protein responsible for transporting iron in the blood. In individuals who consume excessive amounts of alcohol over a prolonged period, the glycosylation (carbohydrate attachment) of transferrin becomes altered. This results in increased levels of carbohydrate-deficient transferrin (CDT).

Unlike liver enzymes such as GGT, which can be elevated due to many non-alcohol-related conditions, CDT is highly specific to sustained alcohol intake, typically reflecting regular consumption of approximately 50–80 g of alcohol per day over 1–2 weeks or longer.

The CDT test is widely used in occupational health, driving licence medicals, legal and forensic settings, and clinical monitoring where objective confirmation of alcohol use or abstinence is required.

Benefits of the CDT Blood Test

1. Highly Specific Marker of Chronic Alcohol Use
   CDT is one of the most reliable blood biomarkers for identifying sustained heavy alcohol consumption.

2. Objective and Tamper-Resistant
   Provides an objective measure not influenced by self-reporting or short-term abstinence.

3. Useful in Legal and Occupational Assessments
   Frequently used in driving licence medicals, workplace health checks, and medico-legal evaluations.

4. Differentiates Alcohol Use from Liver Disease
   Less affected by non-alcoholic liver conditions compared to GGT.

5. Monitors Abstinence or Relapse
   CDT levels decrease with sustained abstinence, making it useful for follow-up monitoring.

6. Complements Other Alcohol Biomarkers
   Works well alongside GGT, MCV, and liver function tests for a comprehensive alcohol assessment.

7. Optional GP Consultation for Clinical Context
   Results can be reviewed with a GP to explain implications and recommend next steps.

Why Do I Need a CDT Blood Test?

You may be advised to have a CDT test if you:

• Require objective evidence of alcohol abstinence

• Are undergoing occupational or legal alcohol assessment

• Have unexplained liver enzyme elevation

• Need monitoring during alcohol reduction or recovery programmes

• Are applying for driving licence reinstatement

• Require confirmation of chronic alcohol intake patterns

CDT is especially valuable when traditional liver markers are inconclusive.

How the Test Works

In-Clinic Blood Test

1. Book Your Appointment

   • Book online or by phone with no referral required.

2. Pre-Test Preparation

   • No fasting required.

   • Avoid alcohol for several days prior if monitoring abstinence.

3. Blood Sample Collection

   • A qualified phlebotomist collects a venous blood sample.

4. Sample Handling

   • Samples are transported under controlled conditions to a UKAS-accredited laboratory.

5. Laboratory Analysis

   • CDT is measured using high-performance liquid chromatography (HPLC) or capillary electrophoresis.

6. Quality Control

   • Strict internal and external quality assurance ensures accuracy.

7. Results Delivery

   • Results are typically available within 5–7 business days.

8. Optional GP Consultation

   • Discuss results and implications with a GP if required.

At-Home Blood Draw (Home or Hotel Service)

1. Book a Home Visit

   • Choose a convenient UK-wide location.

2. Professional Phlebotomist Visit

   • A certified phlebotomist attends your home or hotel.

3. Blood Collection

   • A venous blood sample is collected safely and professionally.

4. Courier to Laboratory

   • Samples are transported the same day.

5. Analysis & Reporting

   • CDT levels are analysed and verified.

6. Optional GP Review

   • Results can be reviewed with a GP if needed.

Your CDT Test Results – Explained

CDT results are typically reported as a percentage of total transferrin (%CDT).

Typical UK Reference Ranges

• Normal: < 1.7 %

• Borderline: 1.7–2.0 %

• Elevated: > 2.0 % (suggestive of chronic alcohol consumption)

Interpretation Notes

• CDT reflects alcohol intake over the previous 1–3 weeks.

• Short periods of abstinence may not normalise CDT immediately.

• Rare genetic transferrin variants or advanced liver disease may affect results.

Interpretation should consider clinical history and other alcohol-related markers.