The key difference between plasma and serum is that the plasma consists of clotting factors while the serum is devoid of the clotting factors.
A common misconception among people is that plasma and serum is the same thing. They are two different substances with a common precursor solution and containing constituents, which makes them unique and required for various medical procedures. The common precursor is blood, and the level of purification of the blood is the determinant of plasma and serum. When we consider blood, it is made up of red blood cells, white blood cells, platelets, proteins, and a watery substance. Plasma is the water part of the blood while serum is the plasma is the part without the clotting factors. These two substances are important in therapeutic and diagnostic procedures in humans, and there are various on-going researches on the specific nature of these substances.
What is Plasma?
Plasma is the basic watery part of the blood. We are able to observe plasma; if we stand a column of blood for about one hour, we can see the precipitation of red cells and white cells with a supernatant straw colored liquid. This liquid is the plasma. Plasma contains fibrinogen, an important factor in the clotting process and other major factors of clotting. Thus, on standing this straw colored liquid tends to clump.
Moreover, this plasma can be spun, so the protein materials with heavier masses tend to precipitate down, leaving better-purified plasma. Plasma is required for diagnostic investigation and especially for therapeutic transfusions in people, who are hypovolemic, deficient in clotting factors, etc. A lesser clot prone plasma is available as cryo poor plasma (CPP), and the removed clotting agents are used in the treatment of haemophiliacs as cryo precipitate.
What is Serum?
Serum is plasma without the clotting factors, mainly the fibrinogen. So serum, on standing does not clot. Usually, to acquire serum, all clotting agents in plasma are removed through progressive centrifuging, or we can get a blood sample, and after allowing it to clot, the supernatant is taken.
Serum includes all the other electrolytes, proteins not used in the clotting process, drugs and toxins. Human serum is usually used for the purpose of diagnostic testing. Other animal seras are used as anti-venom, anti toxins, and vaccinations.
What are the Similarities Between Plasma and Serum?
- Both plasma and serum are present in the blood.
- They are vital components of the blood.
- Both contain metabolites, electrolytes, proteins and antibodies.
- The process of centrifugation can isolate both these from blood.
- Both are fluids.
- They have more than 90% water.
What is the Difference Between Plasma and Serum?
Plasma and serum are two major components of the blood and the circulatory system. Both can be extracted by centrifugation. Plasma is the watery part of the blood without cells while serum is the plasma without the clotting factors. This is the key difference between plasma and serum. Furthermore, the plasma accounts for a higher percentage of the total volume while serum accounts for a small percentage of the total blood volume.
The below infographic presents more details on the difference between plasma and serum in tabular form.
Summary – Plasma vs Serum
Blood is a vital body fluid that is important for the transportation of nutrients and oxygen to every cell in our body and for the elimination of metabolic wastes from the tissues of our body. Plasma and serum are two components of the blood. The water part of the blood is the plasma while serum is the plasma without the clotting factors. Since serum devoid of clotting factors, it is unable to clot, however, since plasma has the clotting factors, it can clot. This is the difference between plasma and serum.
1.“Blood Basics.” Blood Clots, 1 June 2018. Available here