Serum and plasma both are parts of blood. These are widely used in laboratories for performing different types of tests. Blood is the main part of the human body and blood tests help in collecting information about different illnesses as it is a more reliable method.

Serum is the component of blood plasma and acts as a circulating carrier that helps in the transportation of the fatty acids and hormone (Thyroid hormone)

Plasma is the liquid portion of the blood that contains an anticoagulant of clear and yellowish color. Serum and plasma are different in their collection procedure and their uses in performing different types of tests.

For the collection of the plasma anticoagulant EDTA (ethylenediaminetetraacetic acid) is used in the test tubes that prevent the clotting of the blood.

Both are used in different biochemical purposes after their collection. Different types of anticoagulants are used to prevent coagulation in plasma and differentiate it from the Serum.

Mostly used anticoagulants are EDTA and Heparin. Heparin bind to the antithrombin III and accelerates the inactivation of thrombin and other clotting factors. This anticoagulant also used to preserve the folates and vitamins.

The serum is a fluid portion of the blood that remains after the coagulation of the blood by the spinning procedure (centrifugation) varies in color from light to dark brown color.

Anticoagulant (EDTA) is not used in the tubes when the blood is collected for obtaining the serum. The tubes which are used in serum collection called serum separator tubes contain microscopic silica composed of a gel that acts as a barrier between serum and blood.

It does not contain blood cells while plasma contains blood cells that are suspended in it. Serology is the scientific study of the serum. The protein measurement is done on the serum and the normal value of protein is 6 to 8 g/dl. Albumin is the major protein that makes 3.5 to 5.0 g/dl of the serum protein while a reminder is the total globulins.

It contains water (90%) albumin, amino acids, enzymes, hormones, nitrogenous wastes, glucose, etc. Fibrinogen is absent in the serum so that it is coagulated. Serum collection is time-consuming and relatively harder to collect. Serum volume by weight is less than from the plasma. The serum contains immunoglobulins IgG, IgM, IgE, IgD, IgA.

Plasma contains both serum and clotting factors. The composition of plasma is differing from the serum as it contains water, albumin, globulin, amino acids, enzymes, hormones, nitrogenous wastes, nutrients, gases, fibrinogen, etc. it is the main source of electrolytes.

It is easily collected and not time-consuming. It is the 55% volume of the blood by weight. Plasma is 92 -95% water 8% proteins that are albumin, globulin, and fibrinogen-clotting factor, 2% is regulatory proteins, electrolytes, nutrients, hormones, gases. Plasma can be stored for years.

Plasma and Serum Difference in tabular form

DifferenceSerum Plasma
Density 1.024g/ml1.025g/ml
AntibodiesCross react with
recipient antigen
Fight against
foreign body
Life SpanSeveral days at 2-6°CStored yearly
TypeFluidLiquid
FibrinogenAbsentPresent
AnticoagulantNo neededEDTA and Heparin
UsageBlood typing
diagnosing test
Diagnosing blood
clotting like disorders

The density of plasma is 1.025 g/ml while the density of the serum is 1.024g/ml. Both serum and plasma contain the antibodies but these antibodies are differing in their functioning.

The antibodies present the serum cross-react with the recipient antigen while antibodies present in the plasma fight against the foreign body. The serum has a shorter life span in stores as compared to the plasma which has a high life span in storage.

The serum can be stored at 2-6°C for several days. Plasma can be stored for years. As the serum contain electrolytes so it used as anti-venom, anti-toxin, and vaccination.

The serum is used in blood typing and diagnostic tests while plasma is used in diagnostic of blood clotting like disorders. MicroRNAs (miRNAs) concentration is high in the serum as compared to the plasma

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Sana has just completed her MPhil in Microbiology. She loves reading books and the latest discoveries in sciences.

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