difference between plasma and serum

Daniel Parker

2 min read

·

16-03-2025

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Blood is a vital component of our bodies, responsible for transporting oxygen, nutrients, and hormones throughout our systems. Understanding its components is crucial for medical diagnostics and research. Two key components often confused are plasma and serum. While both are liquid parts of blood, they have distinct differences that significantly affect their applications. This article will explore these differences in detail.

Understanding Blood Components

Before diving into the distinctions between plasma and serum, let's briefly review the basic composition of blood. Blood is comprised of several key components:

• Red blood cells (erythrocytes): Carry oxygen throughout the body.
• White blood cells (leukocytes): Part of the immune system, fighting infection.
• Platelets (thrombocytes): Essential for blood clotting.
• Plasma: The liquid component that carries these cells and other substances.

What is Blood Plasma?

Plasma is the pale yellow liquid component of blood that constitutes about 55% of its total volume. It's essentially a complex mixture containing:

• Water: Makes up about 92% of plasma.
• Proteins: Albumin, globulins, and fibrinogen are key proteins with various functions.
• Electrolytes: Sodium, potassium, chloride, and others, crucial for maintaining fluid balance.
• Nutrients: Glucose, amino acids, vitamins, and lipids, providing energy and building blocks for cells.
• Hormones: Chemical messengers that regulate bodily functions.
• Waste products: Urea, creatinine, and others, destined for removal by the kidneys.
• Clotting factors: Proteins necessary for blood coagulation.

What is Blood Serum?

Serum is very similar to plasma but lacks one critical component: fibrinogen. Fibrinogen is a clotting protein. Serum is obtained by allowing blood to clot completely, then separating the liquid portion (serum) from the clot. The clotting process utilizes fibrinogen, thus it is absent in the resulting serum. Serum retains most of the other components found in plasma.

Key Differences Between Plasma and Serum

Here's a table summarizing the primary differences:

When is Each Used?

The choice between plasma and serum depends on the specific application:

• Plasma: Often used in coagulation studies to assess clotting ability. It's also used for certain disease diagnostic tests and in some therapeutic applications (e.g., plasma transfusions).

• Serum: More frequently used in diagnostic testing for various conditions, such as measuring cholesterol levels, liver enzymes, or antibodies. Serum is also used in manufacturing vaccines and other biological products.

Conclusion

While both plasma and serum are essential components of blood, understanding their differences is vital in medical science and research. Plasma contains clotting factors, making it suitable for coagulation studies and some therapeutic uses. Serum, lacking fibrinogen, is widely used in routine diagnostic testing and biopharmaceutical production. The selection between them hinges on the specific analytical requirements of each application.