Blood test results ought to always be interpreted by professionals in the medical field. However, it's also a good thing to have background knowledge of blood tests. A blood test is that test requested by a doctor to be able to make the diagnosis. To carry out a blood test, qualified health care professionals extract a blood sample inside a vein, usually in the arm, with the use of a syringe. A typical blood test checks electrolytes in your body and could also examine complete blood count, blood glucose level, and liver enzyme levels.