Blood count is a test, also called full blood count, that measures the haemoglobin concentration and the numbers of red blood cells, white blood cells, and platelets in 1 cu. mm of blood.The proportion of various white blood cells is measured and the size and shape of the red and white cells is also noted.
A blood count is the most commonly performed blood test and is important for diagnosing anaemia or confirming the presence of an infection to which cells in the blood have responded. It is also used to diagnose disorders such as leukaemia and thrombocytopenia (abnormally low platelet levels).
About 1 to 2 ml of blood is required for a blood count, which is usually performed by an automatic analyser.