Plasma and serum are two frequent terms which are used alternately. It is believed that 8% of total body weight is due to blood. Blood is mainly composed of plasma, serum, white blood cells and red blood cells. White blood cells play very important role in immune system (Body’s defense system) whereas red blood cells involve in transportation of oxygen.
Plasma and serum are components of blood and routinely used for blood testing. Serology is the branch of medical science that is involved in study of blood serum. Following are the key points that could be helpful in understanding the difference between plasma and serum.
Difference in Definition:
Serum is that part of blood which is similar in composition with plasma but exclude clotting factors of blood. Fibrinogen is a protein that is involved in blood coagulation. Fibrinogen is an inactive protein and it performs its functions by converting into fibrin (active form of fibrinogen). Plasma is considered as the medium of blood in which RBCs (Red Blood Cells), WBC (White Blood Cells) and other components of blood are suspended. Plasma proteins with their percentage is indicated below;
- Albumin (60%)
- Globulin (35%)
- Fibrinogen (4%)
- Regulatory proteins, lipoproteins and iron binding proteins (1%)
Difference in Composition:
The components of plasma and serum are similar as both contain hormones, glucose, electrolytes, antibodies, antigens, nutrients and certain other particles except clotting factors which are present only in plasma. So we can say that
Plasma – clotting factors = Serum
Difference in Percentage Volume:
Blood plasma is a clear yellow liquid which is 55% of total volume of blood. The major portion of plasma is water i.g 93% and 7% to is composed of blood cell and other parts. It has a density of 1025 kg/ m3. The percentage volume of serum is less in comparison to plasma and it also lack fibrinogen.
Difference in Isolation Procedure:
It is more difficult and time consuming to separate serum than plasma.
Difference in Use of Anticoagulants:
There is no need to use anticoagulants for separation of serum wheres anticoagulants are necessary to separate plasma.
Difference in Medical Use:
Serum is the most preferred part of blood used in checking blood groups and diagnosis of diseases whereas plasma is delivered to the patients who lack blood cells. Like fresh frozen plasma is used in Hemophilia B. It can also be used for diagnosis of diseases. Plasma is also included by World Health Organization (WHO) in its Model Essential Drug List.
1. Plasma is composed of serum and clotting factors.
2. Serum is the part of blood which lack clotting factors
3. It is difficult to separate serum in comparison to plasma
- Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
- Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall.
- 19th WHO Model List of Essential Medicines (April 2015)” (PDF). WHO. April 2015. Retrieved May 04, 2016
(Updated on 04-05-2016)
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