Health Encyclopedia

Why Your Health Care Provider Takes a Blood Sample

You probably don't enjoy giving a blood sample, but it's an important part of a physical exam. Your health care provider can find out a lot about your overall health from a small sample of your blood.

Here are 4 common tests, according to the American Association of Clinical Chemistry: lipid panel, complete blood cell count (CBC), fasting blood glucose (FBG), and thyroid hormone tests.

Lipid panel

This measures the levels of total cholesterol, LDL (low density lipoprotein cholesterol), HDL (high density lipoprotein cholesterol), and triglycerides that are in your blood.

Complete blood count (CBC)

A complete blood count checks the red blood cells, white blood cells, blood clotting cells (platelets), and sometimes, young red blood cells (reticulocytes). A CBC includes hemoglobin, the part of red blood cells that carries iron, and hematocrit to check the amount of red blood cells and other details about your red blood cells.

Fasting blood glucose (FBG)

A fasting blood glucose checks the amount of glucose or sugar in your blood after not eating for several hours. FBG is used to check for prediabetes or diabetes.

Thyroid hormone

Thyroid tests check for too high or too low levels of thyroid hormone.

For these 4 tests, your health care provider only needs about 2 small vials of blood. In most cases, a nurse or a medical specialist draws the blood sample with a needle from a vein in your arm. The procedure takes only a few minutes.

Medical Reviewers:

  • Holloway, Beth, RN, MEd