Differences Between Plasma and Serum

Contrary to popular belief, serum and plasma are not the same, and hence the terms cannot be used interchangeably. This article will help you to uncover the fundamental difference between plasma and serum quite effectively.

Nonetheless, before resolving the serum vs plasma debate, let’s quickly glance through each concept in brief.

What is Plasma?

Plasma is the liquid part of blood, which is 90% water and makes up around 55% of total blood volume. Its purpose is to transmit proteins, nutrients, hormones and antibodies, among others, throughout the body. Since it runs all over the body, cells also release their waste into plasma. 

Plasma comprises water, protein, lipids, glucose and salt. Typically, plasma helps to regulate the body’s temperature and blood pressure. Plasma comes with a long shelf-life and can be preserved for as long as a year. 

DIY: Find out which of the plasma components acts as the blood clotting factor. 

What is Serum?

In simple words, it is the fluid part that is devoid of the blood clotting factor and cells. When the clotting factor is removed from the blood, its protein fibrinogen changes into fibrin. 

Fibrin is also a protein, but it is insoluble. It helps to repair damaged tissue by forming a clot and preventing the flow of blood through the wound. 

Besides water, plasma also comprises albumin, fibrinogen, globulin, hormones, nutrients, amino acid, nitrogenous waste, etc. Notably, the serum comes with a short shelf-life and can be preserved for just a few months. 

It comes in handy for detecting problems related to cholesterol, blood sugar, blood pressure, etc. 

On that note, let’s proceed to find the serum plasma difference.

Test Your Knowledge: Which of these is formed after blood coagulation?

  1. Plasma

  2. Serum. 

Check out this table below to gain a fair idea about the fundamental differences between blood plasma and serum. 

Difference Between Plasma and Serum





It is a transparent and straw-coloured part of blood. It is slightly alkaline. 

It is the extracellular part of the blood.


Blood cells with salts, glucose, lipid and protein.

Electrolytes, antigens, antibodies, proteins and hormones.


Water and clotting factor.

Proteins like – globulin and albumin.


Fibrinogen is present.

Fibrinogen is absent.

Arrangement of Cell

Cells are suspended.

Clotting usually keeps the cells attached.

Method of Separation

They are separated through the spinning process before clotting.

They are separated through the spinning process after clotting.

Anticoagulant Usage

Anticoagulants are needed.

Anticoagulants are not needed.

Ease of Storage 

It can be preserved for a year.

It can be preserved for a few months.


1.025 g/ml.

1.024 g/ml.


It serves as an essential medium to transport excretory products.

It is among the significant sources of electrolytes. 


Helps to regulate blood pressure and temperature of the body.

Serum is used for diagnosis of cholesterol, sugar, protein, hCG, etc. 

Separation of Blood Plasma and Serum

The composition of serum and plasma can be separated through centrifugation. Notably, each component can be separated because of the varying size, weight and density. 

EDTA Heparin, which is an anticoagulant, is needed to separate blood components like white blood cells and red blood cells from plasma. However, the process to separate serum is relatively complex. 

Find out more about the difference between blood serum and blood plasma in details straight from subject experts. Also, by enrolling in our live online classes, you can gain a better idea about the fundamental difference between blood plasma and serum.

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FAQ (Frequently Asked Questions)

1. What is the Difference Between Plasma and Serum? 

Ans. In simple words, plasma is the straw-coloured transparent part of blood before coagulation, while serum is the undiluted portion of blood. Plasma comprises clotting factor and serum, whereas, the serum contains the remainder part of blood. 

2. What are Serum and Plasma?

Ans. Serum and plasma are the liquid part of the blood, both of which contain at least 90% water. Notably, plasma comprises the blood-clotting agent, whereas there are no blood-clotting factors in serum.

3. What is the Composition of Serum and Plasma?

Ans. Serum comprises electrolytes, hormones, antigens, antibodies and proteins like globulin and albumin. On the other hand, plasma includes suspended blood cells, glucose, salts, proteins and lipids. It also contains water and clotting factors.