The CEA test measures the level of carcinoembryonic antigen (CEA) in the blood.CEA is a protein normally found in the tissue of a developing baby in the womb. The blood level of this protein disappears or becomes very low after birth.he CEA test measures the level of carcinoembryonic antigen (CEA) in the blood.
Blood is made up of cells in a watery base, called plasma. There are three major types of cells blood made up of â red blood cells (RBCs), while blood cells (WBCs) and platelets. 1  They are also known as erythrocytes, carry oxygen to various parts of the body.  They are the most in number, constituting about 40-45% of blood. Their structure is like that of dough nuts.
COMPOSITION OF BLOOD Blood is composed of a yellowish fluid, called plasma, in which are suspended the millions of cells that constitute about 45 per cent by volume of whole blood. It has a characteristic odour and a relative density between 1.056 and 1.066.In an average healthy adult, the volume of blood is one-eleventh of the body weight, or between 4.5 and 6 litres (5 and 6 qt).A great portion of the plasma is composed of water, a medium that facilitates the circulation of the many indispensable factors of which blood is composed.n an average healthy adult, the volume of blood is one-eleventh of the body weight, or between 4.5 and 6 litres (5 and 6 qt).