What is a full blood count?

A full blood count (or FBC) is a blood test which mesures a large number of blood parameters, most notably the Haemoglobin (blood count), white cell count (WCC) and Platelet count.

How is an FBC blood test performed?

An FBC is a blood test requiring a few millilitres of blood from a vein.

Medical Conditions and Symptoms

An FBC may be requested to diagnose or exclude anaemia (low blood count) – which causes tiredness, shortness of breath on exertion and possibly postural light-headedness.

The white blood cell count component of the FBC correlates to some degree to the presence of infection in the body, and your doctor may find this moderately useful when added to the clinical picture of symptoms and signs.

The differential white cell count may be used in chemotherapy patients to determine the number of neutrophils, a type of white blood cell, especially in the setting of a fever.

Platelet count forms part of the FBC panel of tests and may reveal the reason for easy bruising or bleeding problems.

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FBC blood test results explained


  • A LOW Haemoglobin is called anaemia, and has a variety of causes, including chronic (over a long time) blood loss, destruction of red cells, decreased blood cell formation in the bone marrow, defective production of haemoglobin, or chronic illness.
  • A HIGH Haemoglobin is called polycythaemia and may be caused by smoking, chronic lung disease or a blood condition called polycythaemia rubra vera (PRV).

White cell count

  • A VERY LOW WCC would raise concern that the immune system is overwhelmed by infection and may not have enough white blood cells to fight the infection effectively. This is particularly true in the setting of recent chemotherapy.
  • A LOW WCC may occur early on in any infective illness, or may be normal.
  • A HIGH WCC is often due to an infection, which may or may not be severe. Other causes include a seizure, steroid medications such as prednisolone, or as a non-specific “stress response” to pain or illness.
  • A VERY HIGH WCC may be due to severe infection, or less commonly due an acute or chronic form of leukaemia.

What are some things that can cause errors in test results?

Like any other blood test, the FBC needs to be done carefully. Things like incorrectly handling the specimen, labeling it wrong, or having alcohol in the blood will all cause problems with the sample and as such the doctor might ask a person to get it done again.

Platelet count

  • The medical name for a LOW platelet count is thrombocytopaenia, and may be due to a variety of causes, including Idiopathic Thrombocytopaenic Purpura (ITP).
  • Usually, a low platelet count does not result in serious bleeding, unless the platelet count is below 50. Platelet transfusions are only considered in the presence of life-threatening bleeding, or before invasive procedures that may cause serious bleeding, or sometimes when the platelet count is below 10.
  • A HIGH platelet count is called Thrombocytosis.

Related specialists

Related procedures

  • Blood test (venesection)
  • Endoscopy of the Upper Gastrointestinal Tract
  • Colonoscopy
  • Pre-operative Anaesthetic assessment
  • Bone Marrow Biopsy

Related tests

Also known as

  • Full Blood Examination (FBE)
  • Full Blood Picture (FBP)
  • Complete Blood Count (CBC)


* Anemia – American spelling of Anaemia.


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This article is for informational purposes only and should not be taken as medical advice. If in doubt, HealthEngine recommends consulting with a registered health practitioner.

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