Human plasma is a straw-colored or light-yellowish liquid that constitutes approximately 55% of total blood volume. It serves as the fluid medium in which red blood cells, white blood cells, and platelets are suspended and transported throughout the circulatory system. Plasma is obtained by separating these cellular components from whole blood, often through centrifugation. This fluid is fundamental to human health because it acts as the primary distributor of essential substances across the body.
The Biological Makeup and Role of Plasma
Plasma is composed of 91% to 92% water. The remaining 8% to 9% consists of dissolved solids, including a complex mixture of proteins, electrolytes, nutrients, hormones, and waste products. This composition allows plasma to serve as the body’s main transport system, carrying absorbed nutrients like glucose and amino acids to tissues for energy and growth.
The proteins within plasma perform specialized functions. Albumin, the most abundant plasma protein, is synthesized in the liver and maintains the colloidal osmotic pressure of the blood. This pressure keeps fluid within the blood vessels, effectively regulating blood volume and preventing fluid from leaking into surrounding tissues.
Other proteins include immunoglobulins, which are specialized antibodies that recognize and neutralize foreign invaders like bacteria and viruses. Plasma also contains coagulation factors, such as fibrinogen, which are inactive until an injury occurs. These factors activate to form a stable fibrin clot, preventing excessive blood loss.
Plasma transports electrolytes like sodium, potassium, and calcium, which are necessary for nerve and muscle function and maintaining the body’s pH balance. It also carries metabolic waste products, such as urea and creatinine, to the kidneys and liver for filtration and excretion. Hormones secreted by endocrine glands are released directly into the plasma to be delivered to their target organs, ensuring the internal environment remains stable, a state known as homeostasis.
Plasma-Derived Therapies and Treatments
Plasma proteins are separated and concentrated through fractionation to create therapies. This manufacturing process separates donated plasma into specific protein components, which are then purified and processed into pharmaceutical medicines. These therapies are often the only treatment option available for patients suffering from various rare and chronic diseases.
Immunoglobulin (IG) therapy, often administered intravenously as IVIG, is a widely used plasma-derived product. This treatment provides concentrated antibodies to patients with primary immunodeficiency disorders who cannot produce enough infection-fighting antibodies. IG therapy bolsters the immune system, reducing the frequency and severity of infections, and is also used to manage certain autoimmune disorders.
Albumin is manufactured into a therapeutic product used in acute medical settings due to its function in maintaining fluid balance. It is administered to patients experiencing severe trauma, burns, or shock to rapidly restore lost blood volume and maintain blood pressure.
Coagulation factor concentrates are used to treat inherited bleeding disorders, most notably hemophilia. Factor VIII concentrate, for example, provides the missing clotting protein to hemophilia A patients, allowing their blood to clot properly and preventing bleeding episodes.
Plasma-derived therapies also treat conditions like hereditary angioedema (HAE), a rare genetic disorder characterized by recurrent episodes of severe swelling. A specific plasma protein, C1 esterase inhibitor, is extracted and concentrated to treat or prevent the swelling attacks associated with HAE.
The Process and Importance of Plasma Donation
Plasma is collected through plasmapheresis, which differs from a standard whole blood donation. During this process, blood is drawn from the donor and directed into an apheresis machine. Inside the machine, a centrifuge or filtration system separates the liquid plasma from the cellular components, including red blood cells and platelets.
The machine returns the remaining blood cells, often mixed with a saline solution, back to the donor’s body. Because the cellular components are returned, donors can give plasma more frequently than whole blood, sometimes up to twice in a seven-day period. Before donation, individuals undergo a health screening and a check of their vitals to ensure eligibility and safety.
The demand for plasma-derived therapies continues to grow globally. For many rare and chronic conditions, these medicines are the only available treatment, meaning patients rely entirely on a steady supply. Without donated plasma, the manufacturing of these specialized medicines would halt, directly impacting the lives of thousands of people worldwide who need regular infusions.