What does serum refer to in the context of blood?

Serum refers specifically to the liquid portion of coagulated blood. When blood is allowed to clot, it separates into two main components: the solid part, which consists of blood cells and clotting factors, and the liquid part that remains after the clot has formed. This liquid part is what is known as serum.

Serum contains a variety of substances, including electrolytes, antibodies, antigens, hormones, and nutrients, which play crucial roles in various physiological functions. It is important to distinguish between serum and plasma; plasma is the liquid component of uncoagulated blood, which still contains clotting factors. Understanding this distinction is fundamental in phlebotomy and laboratory processes, as many tests are conducted using either serum or plasma depending on the specific requirements of the analysis.