Do You Really Need to Fast Before Taking a Routine Blood Test?

A routine blood test is often prescribed for most healthy people to check or screen for any disorder that has not been previously detected. For example, you may have an elevated blood sugar level without knowing it because your symptoms are mild or you feel just fine. You may be anemic or have a low hemoglobin count, which you find out only after a routine blood test. These screening tests may help detect the presence of a potential health problem before it becomes symptomatic or worse, especially in those who are at risk. People may also get routine blood exams to check if their state of health has improved after receiving treatment for a previously diagnosed disorder.

Routine blood tests usually include a complete blood count (CBC), a blood chemistry test (also called Basic Metabolic Panel), and a blood lipid profile. Requests for particular blood tests may vary for pregnant women, people who are 50 years old and above or young children.  A complete blood count usually measures the number of red blood cells, white blood cells, and platelets, and the amount of hemoglobin (an oxygen-carrier) in the blood. Your hematocrit will help determine whether you are dehydrated, anemic, or if you have bone marrow disorder. A routine blood chemistry test usually examines your blood glucose (sugar) levels, calcium, electrolytes, and kidney function (BUN and creatinine). Your blood lipid profile or lipoprotein panel measures your total cholesterol as well as your bad (LDL), good (HDL), and triglyceride levels. Additional tests may be ordered to check if you are at risk for certain diseases, such as heart disease (blood clotting tests) or liver disease (liver function test).