A Full Blood Count (FBC) is a routine test that can be used to assess your general health or to check for a variety of disorders that affect blood cells. The FBC counts and measures the sizes of the various cells in your blood. These include red blood cells (RBC), white blood cells (WBC) and platelets. Each have specific functions and assessing them can give important information.

Why get tested?

The full blood count (FBC) is one of the most commonly ordered tests because it can give a good overall picture of your health.  It helps to screen for, diagnose, and monitor a wide range of disorders and conditions such as anaemia, clotting problems, infections, blood cancers, and immune system disorders. It provides important information about the types and numbers of different cells in the blood. 

Your blood is made up of solids and liquid.


The solid part of blood

Red blood cells (RBC) 
Red blood cells contain haemoglobin which carries oxygen to all tissues of the body.

White blood cells (WBC) 
There are five types of white blood cells all with different functions:

  • Neutrophils are the most common type of circulating WBCs.  They move to  damaged or infected tissue in the body to engulf and destroy any bacteria.
  • Eosinophils respond to infections caused by parasites, play a role in allergic reactions, and control the extent of immune responses.
  • Basophils are the least common WBC and are involved in allergic reactions. 
  • Lymphocytes can be found in the lymphatic system and blood and are sub divided into three types:
  • B lymphocytes (B cells) produce antibodies as part of the immune response,
  • T lymphocytes (T cells) recognise foreign substances and processes them for removal, and
  • Natural Killer cells (NK cells) directly attack and destroy cancerous cells or cells infected with a virus.
  • Monocytes are similar to neutrophils.  They migrate to the site of an infection and engulf and destroy any bacteria.

These are essential for normal blood clotting. They help stop bleeding by forming together to create a temporary plug in broken blood vessels.


The liquid part of blood

This is a pale yellow liquid that represents about half of the content of whole blood. It contains water, salt and proteins that help blood to  clot, transport nutrients, minerals and hormones throughout your body.  

What the Full Blood Count measures
Red blood cells (RBC)The number of red blood cells in your blood
White blood cells (WBC)The numbers and types of white blood cells in your blood, including neutrophils, lymphocytes, monocytes, eosinophils and basophils
HaemoglobinThe iron-containing, red protein in  your red cells
HaematocritThe amount of space that red blood cells take up in your blood
Mean cell volume (MCV)The average size of your red blood cells
Mean cell haemoglobin (MCH)The amount of oxygen-carrying haemoglobin inside your red blood cells
Mean cell haemoglobin concentration (MCHC)The total haemoglobin inside the red blood cells
Total platelet countThe number of platelet in your blood
Mean platelet volume (MPV)The average size of platelets in your blood

Blood cells are continually being generated.

Your blood is a living thing, and new blood cells must continually be produced to replace those that age, die, or are damaged. New cells are made in the bone marrow, which is the spongy material inside your bones. They stay and mature here until needed and then are released into the blood. Red cells live for about 120 days, platelets live for about six days, and the lifespan of white blood cells depend on the type – from only a few hours to many years.

The production of white cells is driven by any inflammatory process or infection that you might have in your body. The WBCs are released from the bone marrow, travel in the blood to the sight of infection or inflammation and when they have completed their task, the bone marrow stops or reduces their production. 


Having the test


Any preparation?

Your results

Reading your test report

Your results will be presented along with any other tests your doctor ordered on the same form. You will see separate columns or lines for each of these tests.


Reference Intervals

The results of each component will be compared to reference intervals (sometimes called a normal range).

  • Reference intervals are the range of results expected in healthy people 
  • If your result is outside this range, it can be flagged as high (H) or low (L) if they sit outside this range
  • Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation and your results need to be interpreted by your doctor.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms.   It is important that you tell them everything you think might help. 

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely. 

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements, as these  may affect your results. Ask:

  • Why does this test need to be done?
  • Do I need to prepare (such as fast or avoid medications) for the sample collection?
  • Will an abnormal result mean I need further tests?
  • How could it change the course of my care?
  • What will happen next, after the test?

Any more to know?

There is no way you can directly raise the number of your WBCs or change the size or shape of your RBCs. Addressing any underlying diseases or conditions and following a healthy lifestyle will help optimise your body's cell production and your body will take care of the rest.

More information

Pathology and diagnostic imaging reports can be added to your My Health Record.

You and your healthcare provider can now access your results whenever and wherever needed.Get further trustworthy health information and advice from healthdirect.

Last Updated: Thursday, 1st June 2023

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