Serum (blood)

Serum is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not used in blood clotting; all electrolytes, antibodies, antigens, hormones; and any exogenous substances. Serum does not contain white blood cells (leukocytes), red blood cells (erythrocytes), platelets, or clotting factors.