A blood test is when a sample of blood is taken for testing in a laboratory. Blood tests have a wide range of uses and are one of the most common types of medical test.
For example, a blood test can be used to:
- assess your general state of health
- confirm the presence of a bacterial or viral infection
- see how well certain organs, such as the liver and kidneys, are functioning
A blood test usually involves someone taking a blood sample from a blood vessel in your arm. and the usual place for a sample is the inside of the elbow or the back of the hand, where the veins are relatively close to the surface.
Blood samples from children are taken at the Homerton Hospital and if your GP requests a blood test for your child you will be given advice about how to arrange the appointment.
You can find out more about blood tests, their purpose and the way they are performed on the NHS Choices website.