Blood test
Full Blood Count (FBC)
A full blood count is a common blood test that measures the different types of cells in your blood — red cells, white cells and platelets. It helps detect anaemia, infection and many other conditions.
Quick answer
Full Blood Count (FBC): what it is and what the results mean
The full blood count (FBC) is one of the most frequently requested blood tests. It counts and measures red blood cells, white blood cells and platelets.
- Why it is done: It helps diagnose and monitor a wide range of conditions, including anaemia, infections, inflammation, bleeding problems and some blood cancers, and is often part of a general health check.
- Understanding results: Key numbers include haemoglobin (low suggests anaemia), white cell count (raised in infection), and platelets (involved in clotting).
What it is
The full blood count (FBC) is one of the most frequently requested blood tests. It counts and measures red blood cells, white blood cells and platelets.
Why it is done
It helps diagnose and monitor a wide range of conditions, including anaemia, infections, inflammation, bleeding problems and some blood cancers, and is often part of a general health check.
What to expect
A standard blood sample is taken from the arm; no fasting is needed. Results are usually available within a day or so.
Understanding the results
Key numbers include haemoglobin (low suggests anaemia), white cell count (raised in infection), and platelets (involved in clotting). Each is compared to a normal range and interpreted with your other results and symptoms.
Good to know
Risks and limitations
As with any blood test, risks are minimal. An abnormal FBC points towards further tests rather than giving a diagnosis on its own.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Full Blood Count (FBC): frequently asked questions
What does a full blood count check for?
It measures red cells (for anaemia), white cells (for infection or inflammation) and platelets (for clotting), helping detect many conditions.
What does low haemoglobin mean?
Low haemoglobin usually indicates anaemia, which has many causes — from iron deficiency to other conditions. Your doctor will advise on further tests to find the cause.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Royal College of Radiologists / relevant professional body
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