This test measures the amount of estradiol (E2), the form of estrogen made mainly by the ovaries.

This test measures how much of the hormone erythropoietin you have in your blood. You may need this test to figure out what kind of anemia you have.

This blood test is used to find out if you may have an active disease process in your body.

This test looks for several types of receptors on cells in a sample of breast cancer tissue. It helps your doctor figure out which type of breast cancer you have.

This test measures the main electrolytes in your body: sodium, chloride, potassium, and carbon dioxide.

This is a blood test that checks for antibodies to the Epstein-Barr virus. This virus can cause mononucleosis or other conditions in some people.

The direct antiglobulin test, or direct Coombs test, is a blood test used to diagnose a type of anemia caused by your immune system.

This test measures the level of diphtheria antibodies in your blood. You may need this test to find out whether you have or are at risk for diphtheria.

This test measures the amount of the heart medicine digoxin in your blood. When you take digoxin, it's important that the medicine be at the right level for you to benefit from it.

This blood test checks for substances called antibodies. These are made by your body in response to insulin and other chemicals related to insulin. It is used to find out whether you have type 1 or type 2 diabetes.