As with any blood test, the health care provider may limit certain foods or medications shortly before the test to assure an accurate sample. How the Test will Feel When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. Why the Test is Performed Blood is used by the body for transportation of oxygen, food, waste products, and other materials within the body. It is also used for regulation of body temperature, regulation of fluids, and acid-base equilibrium.
Plasma contains various substances dissolved in the fluid.
The cellular portion consists primarily of red blood cells, but also includes white blood cells and platelets . Because blood is used for multiple functions within the body, tests on the blood or its components may give valuable clues in the diagnosis of a multitude of medical conditions. Venipuncture Please read this Important notice .