--- title: "Full blood count (FBC): What to Expect | HealthAnswers" description: "A full blood count (FBC) checks red cells, white cells and platelets, helping GPs detect anaemia, infection and other blood disorders early." url: https://healthanswers.co.uk/tests/full-blood-count/ robots: noindex --- # Full blood count (FBC): What to Expect | HealthAnswers Tests & investigations A full blood count (FBC) checks red cells, white cells and platelets, helping GPs detect anaemia, infection and other blood disorders early. Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026 ## Quick answer What is a full blood count? A full blood count (FBC) is a blood test that measures red cells, white cells and platelets, helping to detect anaemia, infection and other blood disorders. It needs no fasting or special preparation. Your GP explains any abnormal results alongside your symptoms and medical history. ## Who is this page for? This page is for people in the UK who want a plain-English overview of Full blood count (FBC), including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally. ## Who should skip this page? Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland. On this page 4 sections ## Key facts about the full blood count - The test checks haemoglobin levels to identify anaemia in the blood. - White cell counts rise when the body is fighting infection. - Platelets are measured because they help blood to clot. - The test needs no special preparation or fasting. - It is often included as part of routine health screening. ## What a full blood count measures A full blood count looks at three main components of your blood. Red cells carry oxygen around the body, white cells help fight infection, and platelets allow the blood to clot properly. Each component is reported alongside a reference range so you and your GP can see whether your results fall within the expected limits. ## Common abnormalities on a full blood count The most frequent findings on a full blood count are anaemia, signs of infection, and thrombocytopenia, which is a low platelet count. Any of these results usually prompts further tests to clarify the underlying cause rather than a diagnosis from the blood count alone. ## When a full blood count is used A full blood count is commonly requested when someone reports tiredness, unusual bruising or signs of infection. It is also used before surgery and to monitor the effects of certain medicines. Many people also have one done as part of a routine health check even without symptoms. ## Next steps after a full blood count Your GP will look at your full blood count alongside a physical examination and your medical history to decide what it means for you. If an abnormality persists, they may arrange a repeat test or refer you to a specialist for further investigation. ## ! When to speak to a doctor about the full blood count Your GP will arrange a full blood count and discuss any abnormal results with you in person. Call **111** for urgent advice when you are unsure what to do, or if you feel severely unwell with a fever. ## Common questions about the full blood count What does anaemia on a full blood count mean? Anaemia on a full blood count means your haemoglobin level is lower than normal, which can cause tiredness and breathlessness. Iron deficiency is a common cause, so further tests are usually done to find out why. What does a high white cell count mean? A high white cell count is often a sign that the body is fighting an infection. Less commonly it can point to conditions such as leukaemia, so a repeat test and specialist assessment may be needed to rule this out. What does a low platelet count mean? A low platelet count means you may bruise or bleed more easily than usual. It has many possible causes, ranging from viral infections to certain medicines, so your GP will look for the underlying reason. Do I need to fast before a full blood count? No, you do not need to fast before a full blood count. The test can be taken at any time of day regardless of when you last ate. ## Sources - [NHS — Blood Tests](https://www.nhs.uk/conditions/blood-tests) - [NHS — Iron Deficiency Anaemia](https://www.nhs.uk/conditions/iron-deficiency-anaemia)