At a Glance
Why Get Tested?
To determine general health status and to screen for a variety of disorders, such as anaemia and infection, inflammation nutritional status and exposure to toxic substances
When to Get Tested?
As part of a routine medical examination or as determined by your doctor
A blood sample taken from a vein in the arm or a finger-prick or heel-prick (newborns)
Test Preparation Needed?
The Test Sample
What is being tested?
The full blood count (FBC) is one of the most commonly ordered tests and provides important information about the kinds and numbers of cells in the blood: red blood cells, white blood cells and platelets. Abnormalities in any of these types of cells can indicate the presence of important medical disorders.
Blood is composed of a variety of living cells that circulate through the heart, arteries and veins carrying nourishment, hormones, vitamins, antibodies, heat and oxygen to the body's tissues. Blood contains three main components — red blood cells, white blood cells, and platelets — suspended in fluid, called plasma. Red blood cells contain haemoglobin, a protein that carries oxygen to all the tissues of the body. Among other functions, white blood cells are responsible for protecting the body from invasion by foreign substances such as bacteria, fungi and viruses. White blood cells also control the immune process. Platelets help the blood clotting process by plugging holes in broken blood vessels.
How is the sample collected for testing?
The FBC is performed on a blood sample taken by a needle placed in a vein in the arm or by a finger-prick (for children and adults) or heel-prick (for infants).
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.