vérplazma

Vérplazma is the pale‑yellow liquid component of blood in which the blood cells are suspended. It makes up about 55% of total blood volume and is largely water (roughly 90–92%), containing dissolved proteins, electrolytes, nutrients, hormones, gases and waste products. In medical practice, plasma is obtained from blood collected with anticoagulants and separated by centrifugation; serum is the liquid left after coagulation and lacks fibrinogen and other coagulation factors.

Composition: The protein content of plasma includes albumin, globulins and fibrinogen. Albumin accounts for the largest share of plasma proteins and helps maintain oncotic pressure and transport substances. Globulins include various transport and immune proteins, while fibrinogen is a key coagulation factor. Plasma also contains electrolytes such as sodium, potassium and calcium, as well as glucose, lipids, hormones, enzymes and metabolic wastes.

Functions: Plasma acts as the medium for transport of nutrients, hormones and waste products, and helps regulate blood volume, pH and temperature. It provides immune defense through antibodies and other proteins, and it contains the coagulation factors necessary for blood clotting.

Clinical relevance: Plasma is used therapeutically to treat deficiencies of coagulation factors or proteins. Fresh frozen plasma (FFP) contains a broad spectrum of coagulation factors and is used in bleeding disorders and massive transfusions. Plasma derivatives include albumin solutions for volume expansion and intravenous immunoglobulins for immune disorders. Plasma can also be processed via plasmapheresis or fractionated into specific protein products.

Safety and storage: Donor plasma is screened for infectious agents and stored frozen, typically at −18°C or colder, with a shelf life of up to about a year. Transfusion carries risks such as allergic reactions, transfusion-related acute lung injury and alloimmunization, and requires compatibility testing.