What are blood tests for?

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 the phlebotomist taking a blood sample from a blood vessel in your arm. The usual place for a sample is the inside of the elbow or wrist, where the veins are relatively close to the surface.

Routine blood results are usually available within 3 working days but could be longer for a more specialised test.

Find out more about blood tests

You can find out more about blood tests, their purpose and the way they are performed on the NHS Choices website.