Physicians use blood tests to evaluate the function of many organs in the body. Commonly ordered blood tests reveal the function of the kidneys, liver, and thyroid gland. Tests to measure serum cholesterol and triglyceride levels may help determine a risk for coronary artery disease. A count of the white blood cells under a microscope can help to reveal infections and a measure of red blood cells can reveal a critical decrease in red blood cells or anemia.
Anemia is a blood condition that occurs either when there are not enough red blood cells or when there is not enough hemoglobin in the red blood cells. Hemoglobin is the iron-containing substance in red blood cells that enables the blood to transport oxygen through the body.