Serum vs Plasma- Definition and 17 Major Differences

Serum and plasma are two terms that are often used interchangeably in the context of blood. However, they are not the same thing and have different properties and functions. In this article, we will explain what serum and plasma are, how they are obtained, and what are the major differences between them.

Blood is a complex fluid that consists of various components, such as red blood cells, white blood cells, platelets, and plasma. Plasma is the liquid part of blood that carries the blood cells and other substances throughout the body. It makes up about 55% of the total blood volume and contains about 90% water and 10% dissolved substances, such as proteins, hormones, electrolytes, nutrients, waste products, and antibodies.

Serum is the fluid that remains after blood has been allowed to clot and the clot has been removed. It is essentially plasma without the clotting factors, such as fibrinogen, prothrombin, and other proteins involved in blood coagulation. Serum contains about 92% water and 8% dissolved substances, such as albumin, globulins, immunoglobulins, hormones, electrolytes, nutrients, waste products, and antibodies.

Serum and plasma are both important for various diagnostic and therapeutic purposes. They can be used to measure the levels of different substances in the blood, such as glucose, cholesterol, hormones, enzymes, antibodies, drugs, toxins, etc. They can also be used to transfuse patients who need blood components or to produce vaccines and other biological products.

However, serum and plasma are not interchangeable and have different advantages and disadvantages depending on the purpose. In the next section, we will discuss the differences between serum and plasma in more detail.

Serum and plasma are both liquid components of blood that contain various substances such as electrolytes, antibodies, hormones, proteins, and waste products. However, they differ in one crucial aspect: plasma contains clotting factors and blood cells, while serum does not.

Clotting factors are proteins that help blood to form clots and stop bleeding when a blood vessel is damaged. Blood cells are red blood cells, white blood cells, and platelets that perform various functions such as carrying oxygen, fighting infections, and forming clots. Plasma is the liquid part of blood that contains both clotting factors and blood cells. Serum is the liquid part of blood that remains after clotting factors and blood cells have been removed.

The process of obtaining serum and plasma from whole blood is different. To get plasma, an anticoagulant (a substance that prevents clotting) is added to the blood sample and then it is centrifuged (spun at high speed). The anticoagulant prevents the blood from clotting and allows the separation of plasma from the solid components of blood. The plasma is then collected from the top layer of the centrifuged tube.

To get serum, no anticoagulant is added to the blood sample and it is allowed to clot at room temperature for 15-30 minutes. The clotting process removes the clotting factors and the blood cells from the liquid part of blood. The serum is then separated from the clot by centrifugation and collected from the top layer of the tube.

The following table summarizes some of the main differences between serum and plasma:

Serum and plasma are both important components of blood that have different functions and applications. Serum is the liquid part of blood that remains after clotting, while plasma is the liquid part of blood that contains clotting factors. Serum and plasma differ in their composition, preparation, storage, uses, and tests. Some of the major differences between serum and plasma are:

• Serum has no fibrinogen or other clotting factors, while plasma has them.
• Serum is obtained by centrifuging clotted blood, while plasma is obtained by centrifuging anticoagulated blood.
• Serum can be stored at room temperature for up to 24 hours, while plasma needs to be frozen or refrigerated.
• Serum is used for immunological tests, such as antibody detection and serology, while plasma is used for coagulation tests, such as prothrombin time and partial thromboplastin time.
• Serum has higher concentrations of electrolytes, hormones, and proteins than plasma.
• Serum has lower pH and osmolarity than plasma.

Serum and plasma are both valuable sources of information for diagnosing and monitoring various diseases and conditions. Knowing the differences between serum and plasma can help in choosing the appropriate sample type and method for different tests and purposes.

Serum and plasma are both valuable sources of biomolecules and biomarkers that can be used for various purposes in medicine, research, and industry. Some of the applications of serum and plasma are:

• Blood transfusion: Plasma is the main component of blood that carries red blood cells, white blood cells, platelets, and other substances. Plasma can be transfused to patients who have lost blood due to trauma, surgery, or bleeding disorders. Plasma can also be separated into different fractions that contain specific proteins, such as clotting factors, immunoglobulins, or albumin, and administered to patients who have deficiencies or diseases related to these proteins.
• Serological testing: Serum is the fluid that remains after blood clots and contains antibodies that are produced by the immune system in response to infections or vaccinations. Serum can be used to test for the presence or absence of antibodies against various pathogens, such as viruses, bacteria, fungi, or parasites. Serological testing can help diagnose infections, monitor immune status, or determine immunity or susceptibility to certain diseases.
• Biochemical analysis: Serum and plasma contain various metabolites, hormones, enzymes, and other molecules that reflect the physiological state of the body. Serum and plasma can be analyzed to measure the levels of these molecules and assess the function or dysfunction of various organs or systems, such as the liver, kidney, heart, thyroid, or glucose metabolism. Biochemical analysis can help diagnose diseases, monitor treatment effects, or screen for risk factors.
• Biomedical research: Serum and plasma are rich sources of information that can reveal the molecular mechanisms of health and disease. Serum and plasma can be used to identify biomarkers that are associated with specific conditions, such as cancer, diabetes, cardiovascular disease, or neurodegenerative disease. Biomarkers can help detect diseases early, predict outcomes, or guide therapies. Serum and plasma can also be used to study the effects of drugs, toxins, or environmental factors on the body.
• Biotechnology industry: Serum and plasma contain various proteins that have biological activities or functions that can be exploited for industrial purposes. For example, serum albumin is a protein that binds and transports various substances in the blood and can be used as a stabilizer or carrier for drugs or vaccines. Plasma-derived immunoglobulins are antibodies that can neutralize or bind to specific antigens and can be used as therapeutics or diagnostics. Other plasma proteins, such as fibrinogen, thrombin, or collagen, can be used as biomaterials for tissue engineering or wound healing.

These are some of the applications of serum and plasma that demonstrate their importance and utility in various fields. Serum and plasma are not only essential components of blood but also valuable resources for science and society.

Plasma contains clotting factors, which are proteins that help the blood to clot when there is an injury. Serum does not contain clotting factors, as they are removed during the process of clot formation. Clotting factors are important for preventing excessive bleeding and promoting wound healing. Some of the clotting factors present in plasma are fibrinogen, prothrombin, and factor VIII. Serum can be used to measure the levels of antibodies, hormones, and other substances in the blood, as they are not affected by the clotting factors. Plasma can be used to measure the levels of clotting factors and other proteins that are involved in blood coagulation.

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