Serum Vs. Plasma

The terms serum and plasma are used in concern to blood related works. Very often, you may come across medical diagnostic tests, performed specifically on plasma and serum. In fact, there is only a very thin line between the two. Nevertheless, both the concepts are very vast in medical field. For better understanding, you need to first learn about blood, its function and components. Hence, before we discuss serum vs. plasma, let's find out some information on human blood first.

Information on Blood

As we all are aware, blood is the red colored bodily fluid that is circulated trough blood vessels, namely, arteries, veins and capillaries. About 8 percent of the total body weight is contributed by blood. It does the major function of distributing oxygen and essential nutrients (e.g. glucose, amino acids, fatty acids, etc.) to body cells and tissues. Also, blood is crucial for removing waste products (e.g. carbon dioxide, lactic acid, urea, etc.) from the same cells and tissues. Other than these, blood is responsible for immune system responses, clotting, regulation of body temperature and many other functions.

What is the Difference Between Serum and Plasma?

Serum and plasma are both components of blood. Thus, both are used frequently while performing blood tests or any other blood works. In fact, the ability of blood to perform major bodily functions is attributed to plasma, blood cells, proteins, hormones, glucose and other components of the blood. And the branch of medical science that deals with blood serum is called serology. Following are some points related to the difference between serum and plasma.

Actual Definition
Serum is nothing but plasma, after excluding fibrinogen and other blood clotting factors. Fibrinogen is a type of protein, responsible for coagulation of blood, by converting itself into fibrin. Whereas plasma is defined as the medium of blood, to which blood cells (red blood cells and white blood cells) and other components are suspended.

Components
Serum is made up of non-clotting proteins, glucose, nutrients, electrolytes, hormones, antigens, antibodies and other particles. While the components of plasma are same as that of serum, except for fibrinogens and clotting factors that are absent in serum. In short, the relation between serum and plasma can be put as - 'serum = plasma after removal of clotting factors'.

Percentage Volume
Blood plasma accounts to more than half of the volume of blood. Out of this 90 percent of the volume is made up of water, the remaining 10 percent comprises the blood cells, nutrients and other parts. Since plasma accounts to about 55 percent of blood, definitely the percentage volume of serum is lesser than this. After all, serum is plasma devoid of clotting factors.

Isolation Procedure
Separation of serum is more tedious and time-consuming than plasma extraction. For isolation of serum, first a blood sample is allowed to clot, after which the coagulated blood is centrifuged. The liquid supernatant formed at the top portion is serum. The procedure for extraction of plasma is very simple; blood sample is spun by using a centrifuge apparatus. The heavier blood cells settle at the bottom, and blood plasma is collected from the upper layer.

Usage in Medicine
Serum is used for regular blood group testing (or checking blood types) and disease diagnostic purposes. On the other hand, blood plasma is delivered to supplement lack of blood components in patients. It can also be used for detection of diseases. Before storage and after separation, plasma is treated with an anticoagulant substance to prevent clotting.

To be more precise, the main differentiating point between to serum vs. plasma is the clotting factor, which is present in plasma and absent in serum. Otherwise, they are both parts of the blood having similar color, i.e., straw or light yellow. However, this color may fluctuate depending upon the general health of the individual, from whom the blood sample has been drawn.