We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Difference Between Plasma and Serum?

By Dulce Corazon
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Plasma and serum are both found in blood. Blood contains the red blood cells (RBC), the platelets, the white blood cells (WBC), and several other important substances, including electrolytes, fibrinogen, hormones, and antibodies. These are all suspended in the fluid portion of the blood, which is the plasma. The main difference between plasma and serum is the absence of fibrinogen, an important clotting factor, in the serum.

Neither plasma or serum contain red or while blood cells or platelets, but they contain all the other substances, except for the fibrinogen, which is not present in the serum. Inside the body, these blood components cannot be distinguished from each other, but in the laboratory, they can be separated and measured in order to help with the diagnosis and monitoring of diseases. An adequate amount of blood is usually extracted from the vein in the arm of the patient and placed in a clear test tube with the name of the patient on it. It is often accompanied by a list of laboratory tests to be done.

Certain tests may require the use of plasma for the measurement of substances contained in blood. There are also tests that require only serum, such as the test for calcium, glucose, potassium, and cholesterol. When the laboratory tests to be done require the use of serum, the blood in the test tube is frequently spun in a centrifuge, a machine used to separate the components. After spinning, a blood clot that contains the fibrinogen is often visible at the bottom of the tube, and the clear yellow liquid on top is the serum. The serum will then be separated from the clot, and be subjected to different test procedures.

When blood is exposed outside the body, its tendency is to clot due to the presence of the fibrinogen. Certain tests, such as the platelet function tests, often require the use of plasma. In order to separate the plasma from the solid components in blood and at the same time prevent it from clotting, an anticoagulant is usually added to the sample before spinning. Anticoagulants are chemicals that help prevent blood clot formation, and they are also used as medications to prevent blood from clotting inside the bloodstream.

The transparency and color of plasma and serum are usually clear and yellowish. They can, however, become cloudy due to the presence of fats or bacterial contamination. Both may also appear reddish pink, which is a sign of hemolysis or breakdown of RBC. This can occur during blood extraction or from improper handling of the blood specimen. These variations in the color can sometimes lead to the blood sample being rejected, because it can cause inaccurate test results.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By anon353575 — On Oct 31, 2013

I am a medical student and doing D.M.L.T. I want to know about the differences between the serum and the plasma.

By anon321245 — On Feb 21, 2013

Can you visually tell the difference between serum and plasma?

By anon295948 — On Oct 09, 2012

What are the differences in percentage of proteins in serum and plasma?

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.