Coombs (Direct Antiglobulin Test)
The Direct Coombs test detects antibodies attached to red blood cells. It helps diagnose immune-mediated haemolytic anaemia and related conditions.
Turnaround time
4 days
Biomarkers count
1
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Details about Coombs (Direct Antiglobulin Test)
What is the Coombs (Direct Antiglobulin Test)?
The Direct Coombs test, also known as the Direct Antiglobulin Test (DAT), is a blood test used to detect antibodies or complement proteins that are bound directly to the surface of red blood cells.
Under normal conditions, red blood cells circulate freely without immune interference. In certain conditions, the immune system mistakenly targets red blood cells, causing them to be destroyed prematurely (haemolysis). The Direct Coombs test identifies this immune attachment, helping confirm immune-mediated red blood cell destruction.
This test is widely used in haematology, transfusion medicine, and immunology.
Why do I need a Direct Coombs test?
The Direct Coombs test is used when there is suspicion that red blood cells are being destroyed by the immune system. It helps determine whether haemolysis has an immune cause.
You may need a Direct Coombs test if you have:
- Unexplained anaemia
- Rapid drop in haemoglobin levels
- Jaundice (yellowing of skin or eyes)
- Dark urine
- Fatigue or weakness
- Enlarged spleen
- A reaction following blood transfusion
- Suspected autoimmune haemolytic anaemia
Conditions commonly associated with a positive Direct Coombs test include:
- Autoimmune haemolytic anaemia
- Transfusion reactions
- Haemolytic disease of the newborn
- Drug-induced haemolysis
- Certain infections or autoimmune disorders
Benefits of the Direct Coombs test
- Identifies immune-mediated haemolysis
Confirms antibody-related red blood cell destruction. - Supports diagnosis of autoimmune anaemia
Essential in haematological investigations. - Useful in transfusion reactions
Helps determine cause of post-transfusion haemolysis. - Guides further testing and treatment
Supports clinical decision-making. - Clinically recognised diagnostic tool
Used in NHS and private haematology services. - Simple blood test
Requires only a single blood sample. - Applicable across age groups
Used in adults, children, and neonates. - Improves diagnostic accuracy
Differentiates immune from non-immune causes.
Step by step – how the test works
You can access Direct Coombs testing UK-wide through two options:
- Clinic appointment
Attend your nearest UK clinic where a healthcare professional will take your blood sample. - At-home or hotel visit (£60 extra)
A qualified phlebotomist visits your home or hotel, so you don’t need to travel.
Your blood sample is analysed in an accredited UK laboratory, and results are delivered securely.
Your results explained
Negative Direct Coombs test
No antibodies or complement detected on red blood cells. Immune-mediated haemolysis is unlikely.
Typical laboratory interpretation:
- DAT: Negative
Weakly positive Direct Coombs test
Small amounts of antibodies or complement detected. May indicate early or mild immune activity.
Typical laboratory interpretation:
- DAT: Weakly positive
Positive Direct Coombs test
Antibodies or complement are present on red blood cells, indicating immune-mediated haemolysis.
Typical laboratory interpretation:
- DAT: Positive
Results must always be interpreted alongside clinical findings and other blood tests.
How It Works
Simple steps to get your results
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Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.