Blood test is a great rapid test for COVID-19 detection. The different specimens will have big different final results while doing covid-19 antibody test. All rapid test will require to detect based on whole blood, plasma or serum. So, what’s the difference between serum and plasma? Serum VS Plasma as below.
Blood consists of plasma and blood cells.
Plasma is equivalent to the intercellular substance of connective tissue. Serum is a light yellow translucent liquid. In addition to a large amount of water, plasma contains inorganic salts, fibrinogen, albumin, globulin, enzymes, hormones, and various nutrients, etc. These substances do not have a certain shape, but have important physiological functions.
1L of plasma contains 900～910g water (90%～91%), 65～85g protein (6.5%～8.5%) and 20g low molecular substance (2%). There are many electrolytes and small molecular organic compounds in low molecular substances, such as metabolites and some other hormones. The electrolyte content in plasma is basically the same as that in tissue fluid.
(2) Blood cells
During the life of the body, blood cells are constantly metabolizing. The average life span of red blood cells is about 120 days, and the life span of granular white blood cells and platelets generally does not exceed 10 days. The life span of lymphocytes varies from a few hours to several years.
Blood cells and platelets are produced from hematopoietic organs. Red blood cells, granular white blood cells and platelets are produced by red bone marrow, while agranulocytes are produced by lymph nodes and spleen.
There are three types of blood cells: red blood cells, white blood cells, and platelets.
An adult has about 5 liters of blood. By volume, blood cells account for about 45% of blood. Each liter of blood has:
5x1012 Red blood cells (about 45% of blood volume): In mammals, mature red blood cells have no nucleus and organelles. They have heme to transport oxygen. The glycoprotein on the red blood cell determines the blood type. The proportion of red blood cells in the blood is called hematocrit. The total surface area of all red blood cells in the human body is approximately 2000 times the area of the skin outside the body.
9x1011 White blood cells (about 1.0% of blood volume): They are part of the immune system, responsible for destroying and removing old or abnormal cells and cell debris, and attacking pathogens and foreign objects.
3x1011 Platelets (approximately less than 1% of the blood volume): They are responsible for blood clotting, turning fibrinogen into fibrin. Fibrin forms a network to gather red blood cells to form a thrombus, which prevents more blood loss and helps prevent bacteria from entering the body.
Plasma definition: Plasma refers to the liquid part of the whole blood after separation. It is based on a solution of crystalline substances, including water and a variety of electrolytes, as well as small molecules of organic matter and gases dissolved in it.
Plasma is equivalent to the intercellular stroma of connective tissue. Plasma has a pale yellowcolor because it contains bilirubin. Water makes up 90 to 92 percent of the chemical composition of the plasma, with the other 10 percent in the form of solutes in proteins, nutrients, hormones, cholesterol, and other important substances.
Carry blood cells, transport substances needed to maintain the body and producing waste, etc.
Plasma donation is one of the methods of component blood donation. The technology of plasma donation is to extract the human blood from the body, separate it in the automatic machine, and return red blood cells to the donor. Only the plasma part is collected. The whole process uses disposable consumables and is completed in completely enclosed environment. Plasma donation is one of best way to treat the novel coronavirus for it includes antibody of SARS-CoV-2. How to donate plasma? Should consult the local authority department.
Serum definition: Blood serum refers to the gelatinous fluid in plasma after fibrinogen is removed.
It is mainly composed of water and various chemical components, such as albumin, α1、α2、β、γ-globulin, triglyceride, total cholesterol, alanine aminotransferase and so on. Serum contains a variety of plasma proteins, peptides, fats, carbohydrates, growth factors, hormones, inorganic substances, and so on. These substances promote cell growth or inhibit growth activity so as to achieve physiological balance.
Situations in which serum rather than plasma is commonly used:
Antibodies exist in serum, lymph, mucosal secretions and tissues, but with the highest content in serum. And antibodies are often obtained by the separation of the serum, so antibodies are also called anti-serum.
There is no relevance between plasma membrane and plasma.
Plasma membrane was used to be called “cell membrane”, which is a very thin membrane that surrounds the cell surface and is mainly composed of membrane lipids and membrane proteins.
The basic role of the plasma membrane is to maintain the relative stability of the intracellular microenvironment and to participate in the material exchange with the external environment. In addition, it plays a crucial part in the survival, growth, division and differentiation of cells.
Serum vs plasma: The difference between them is clearly shown in above information, which can help design IVD product while doing lateral flow assay development in in-vitro diagnostics.