Serum vs Plasma: Key Differences, Composition, and Clinical Uses
Medically Reviewed
Hematology

Serum vs Plasma: Key Differences, Composition, and Clinical Uses

Discover the key differences between serum and plasma, including their composition, preparation, and clinical uses. Learn which blood component is used for various diagnostic and therapeutic applications.

By Dayyal Dg.
Published:
Print this Page Email this Article
BS
Login to get unlimited free access
Be the first to comment!
Serum vs plasma
Difference between serum and plasma.

Serum refers to the clear, yellowish fluid that remains after blood has undergone clotting. It is devoid of clotting factors, making it ideal for diagnostic tests where clotting proteins are unnecessary. Serum is obtained after allowing a whole blood sample, typically collected in a plain tube, to clot naturally. Once the blood has clotted, the serum can be separated and utilized in various biochemical and serological tests.

On the other hand, plasma is the liquid portion of blood that retains clotting factors, including fibrinogen, making it vital for coagulation studies and plasma transfusions. Plasma is acquired by centrifuging anticoagulated whole blood, resulting in a supernatant liquid that is rich in proteins and clotting agents. Its role is significant in both diagnostic testing and therapeutic interventions, especially in coagulation disorders.

The primary differences between blood serum vs plasma include:

  1. Clotting Factors: Plasma contains fibrinogen and all other clotting proteins, whereas serum lacks fibrinogen as it is removed during the clotting process.
  2. Collection Time: Plasma can be separated from whole blood immediately after sample collection through centrifugation, whereas serum requires at least 30 minutes to form from clotted blood.
  3. Sample Yield: For an equivalent volume of whole blood, the quantity of plasma obtained is generally higher compared to serum.
  4. Anticoagulant Influence: The use of anticoagulants in plasma preparation can alter the concentration of certain analytes, such as sodium, potassium, and lithium, which may affect the accuracy of specific tests.
Table 1: Difference between serum and plasma.
FeatureSerumPlasma
Definition The liquid component of blood after clotting, without clotting factors. The liquid component of blood that contains clotting factors, derived from blood treated with an anticoagulant.
Composition Contains water, electrolytes, hormones, proteins (e.g., albumin, globulins), antibodies, and waste products but lacks clotting proteins like fibrinogen. Contains water, electrolytes, hormones, proteins (including clotting factors like fibrinogen), antibodies, and waste products.
Clotting Factors Lacks clotting factors, such as fibrinogen, because they are used up in the clotting process. Contains clotting factors, including fibrinogen, prothrombin, and other coagulation proteins.
Preparation Obtained by allowing blood to clot naturally in a tube, followed by centrifugation to separate the liquid component from the clot. Obtained by adding an anticoagulant (e.g., EDTA, citrate, or heparin) to prevent clotting, followed by centrifugation to separate the plasma from the blood cells.
Anticoagulant Use No anticoagulant is used, allowing blood to clot. Requires an anticoagulant to prevent blood from clotting.
Appearance Clear, pale yellow liquid, but can be slightly more transparent compared to plasma as it lacks clotting proteins. Slightly turbid, pale yellow liquid due to the presence of clotting factors.
Common Tests Used in many diagnostic tests, especially in biochemistry and immunology, such as liver function tests, renal function tests, hormone levels, and antibody tests. Used for coagulation studies, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), and for plasma transfusions in therapeutic settings.
Storage Stability Generally stable and can be stored frozen for a long period without significant degradation of analytes. May have a shorter shelf life compared to serum due to the presence of clotting factors, which may degrade over time if not stored properly.
Clinical Uses Ideal for many biochemical and serological tests as it eliminates interference from clotting factors. Essential for tests that require clotting factors, including coagulation tests and therapeutic plasma uses, such as treating clotting disorders.
Medical Applications Used in diagnostic testing for various conditions, including metabolic, liver, and kidney function assessments. Utilized in therapeutic plasma transfusions for patients with bleeding disorders and in coagulation tests to assess clotting function.

FAQs

  1. What is the difference between serum and plasma in a blood test?

    Serum is the liquid part of blood after clotting, without clotting factors, while plasma is the liquid part of blood that contains clotting factors, obtained by preventing the blood from clotting. Both are used in different types of blood tests depending on whether clotting factors are needed for the test.

  2. Why is plasma used instead of serum in some tests?

    Plasma is used in tests that require the presence of clotting factors, such as coagulation tests. Since plasma still contains fibrinogen and other coagulation proteins, it is ideal for assessing blood clotting function.

  3. Can serum and plasma be used interchangeably in blood tests?

    No, serum and plasma cannot always be used interchangeably. The choice between serum and plasma depends on the specific test. For example, coagulation tests require plasma because it contains clotting factors, while many biochemistry tests use serum.

  4. What types of diagnostic tests use serum?

    Serum is commonly used for diagnostic tests such as liver function tests, renal function tests, hormone assays, and antibody detection. These tests do not require the presence of clotting factors, making serum the preferred choice.

  5. How is plasma separated from blood?

    Plasma is separated from blood by adding an anticoagulant to prevent clotting, followed by centrifugation to separate the plasma from the blood cells. This results in a clear liquid that contains all the components of blood except the cells.

  6. What is serum used for in medical applications?

    Serum is used in various medical and diagnostic applications, including metabolic panels, liver and kidney function tests, and hormone and antibody measurements. Since it lacks clotting factors, it provides a clearer sample for these tests.

  7. Is plasma used in transfusions?

    Yes, plasma is used in therapeutic transfusions, especially for patients with bleeding disorders or those who require clotting factor replacement. Plasma transfusions help to replenish clotting factors in patients with conditions like hemophilia or during surgery.

  8. How are serum and plasma stored?

    Serum is generally stable and can be stored frozen for long periods without significant degradation of its components. Plasma can also be stored, but the presence of clotting factors may require specific handling and storage conditions to maintain stability.

  9. Why is it important to know the difference between serum and plasma?

    Understanding the difference between serum and plasma is important for healthcare professionals and patients alike because it impacts the accuracy of diagnostic tests and treatment decisions. Using the correct component of blood ensures that test results are reliable and that therapies are effective.

Last Updated:

Cite this page:

Dayyal Dg.. “Serum vs Plasma: Key Differences, Composition, and Clinical Uses.” BioScience. BioScience ISSN 2521-5760, 22 July 2017. <https://www.bioscience.com.pk/en/topics/hematology/use-of-plasma-vs-serum-difference-between-plasma-and-serum>. Dayyal Dg.. (2017, July 22). “Serum vs Plasma: Key Differences, Composition, and Clinical Uses.” BioScience. ISSN 2521-5760. Retrieved August 18, 2024 from https://www.bioscience.com.pk/en/topics/hematology/use-of-plasma-vs-serum-difference-between-plasma-and-serum Dayyal Dg.. “Serum vs Plasma: Key Differences, Composition, and Clinical Uses.” BioScience. ISSN 2521-5760. https://www.bioscience.com.pk/en/topics/hematology/use-of-plasma-vs-serum-difference-between-plasma-and-serum (accessed August 18, 2024).
  • Posted by Dayyal Dg.

Follow us on social media

Facebook Twitter Instagram Koo App YouTube Google News
End of the article