Plasma vs Serum – Difference Between Plasma and Serum

Our blood contains various types of elements that have an essential role to play. It is important for these elements to work in sync in order to achieve and meet important functions of the body. Plasma and serum are elements found in the blood which are extremely essential for the body.

Plasma vs Serum

The main difference between Plasma and Serum is that Plasma is a liquid blood element that has the work of holding blood cells in a blood suspension. On the other hand, Serum is a liquid that is rich in protein, and it has a tendency to separate out on coagulation of blood.

Plasma and Serum

The majority part of the blood constitutes Plasma. It is a liquid element that is present in the blood and plays the role of holding the blood cells in a suspension of blood. It has clotting factors that make it very essential. The density of plasma is 1.025 g/ml.

The serum has nothing to do with clotting making its contribution zero in the clotting process. It is extremely rich in protein and also sometimes regarded as a plasma without clotting properties. When the blood coagulates, the serum separates itself from the blood. The density of serum is 1.024 g/ml.

Comparison Table Between Plasma and Serum

Parameters of ComparisonPlasmaSerum
ComponentsIt consists of clotting factors as well as serum.It consists of protein but does not have blood cells.
Acquired fromThe spinning prior to clotting gives plasma.The spinning after clotting gives Serum.
AnticoagulantsIts separation from the blood requires anticoagulants.Its separation from blood does not require anticoagulants.
SeparationThe process of separation takes less time and is easy.The process of separation takes more time and is difficult.
Clotting factorsClotting factors are present in the plasma.Clotting factors are not present in the serum.

What is Plasma?

Plasma can be simply regarded as the liquid part of the blood. It is what gives blood the liquid property and keeps it in that state. From the total volume of blood, plasma acquires about 55%, making it the major part of the blood. Since it is a liquid, there has to be a good amount of water content. It is scientifically tested and proven that plasma is about 92% water. It can also be regarded as extracellular fluid. The color of plasma is very similar to that of straw and is also known as a solution of protein and salt.

Plasma contains a large number of different proteins. All these proteins are present in the plasma in dissolved form. Some of these proteins are fibrinogen, albumin, and globulin. Other than proteins, plasma also has a good constituency of hormones, glucose, electrolytes, clotting factors, oxygen, and carbon dioxide. Plasma is important for various factors. It helps in balancing the pH of the body, maintaining blood pressure, and in exchange for minerals (potassium, sodium, etc.), it acts as a medium. Centrifugation is the process involved in separating plasma from the blood. This process of separation is very easy and does not take a lot of time. Transfusion of plasma is needed for liver patients, trauma patients, etc.

What is Serum?

The serum has a very unique color that even supports the color of blood a little. It resembles the color of amber. It is completely the opposite of plasma in the case of clotting. This indicates that serum does not have any clotting factors or properties. This lack of clotting properties in serum also gave it the recognition as the plasma without clotting factors. The serum consists of all the proteins, excluding the ones that are required for clotting. Apart from the proteins, the serum also consists of antigens, electrolytes, exogenous components, antibodies, and hormones. The serum is regarded as a splendid source of electrolytes too. It can be conveniently stored at a temperature of 2 to 6 degrees celsius for a number of days. 

The study of serum is known as Serology. The study of serum can be useful in testing the serum for a number of diseases and health conditions. These diagnostic tests are usually for enzymes and hormones. One more important use of serum can be the detection of blood groups. For the separation of serum from the blood too, a centrifugal process is brought into use. This separation process is harder and takes a lot more time in comparison to the case of plasma.

Main Differences Between Plasma and Serum

  1. The blood volume taken up by plasma is about 55%, whereas it is very low in the case of serum.
  2. There are essential clotting factors present in Plasma. On the other hand, Serum does not possess clotting factors.
  3. There is a special need for anticoagulants for the separation of plasma from blood, whereas it is not required in the case of Serum.
  4. The process of separation of plasma from the blood is very easy and does not take much time, whereas the same process takes more time and is harder in the case of Serum.
  5. The spinning action before clotting results in acquiring plasma, whereas the spinning after clotting gives serum.


The main properties of plasma and serum themselves make them different from each other. These are also sometimes called the complete opposite of each other. On the one hand, Plasma is the root element for clotting. On the other hand, the serum doesn’t even have the properties that help in clotting. The storage temperatures of plasma and serum are very far from each other too.

Plasma needs to be kept at a temperature of -18 degrees and can be left in this state for about a year. They use coagulation as a method of preservation. On the other hand, serum can only be preserved for a few days and kept at a temperature of 2 degrees to 6 degrees. It is convenient to differentiate them when one knows each term completely.


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