plasmaprotein

Plasmaprotein, more commonly referred to as plasma protein, denotes the soluble proteins found in blood plasma. They constitute a major portion of plasma and are essential for maintaining proper fluid balance, transporting substances, and supporting immune and coagulation processes. The major fractions are albumin, globulins, and fibrinogen, with albumin and globulins making up the bulk of plasma proteins and fibrinogen being a key component of the coagulation system.

Albumin is the most abundant plasma protein. It helps maintain colloid osmotic pressure to keep fluid within the bloodstream and also serves as a carrier for many endogenous and exogenous compounds, including fatty acids, hormones, and drugs. Globulins are a diverse group that includes alpha and beta globulins, which transport metals and lipids and participate in various enzymatic and transport roles, and gamma globulins, which are largely immunoglobulins or antibodies produced by plasma cells and other immune cells. Fibrinogen is a clotting factor that is converted to fibrin during coagulation, forming the meshwork that stabilizes a blood clot. Some plasma proteins function as acute-phase reactants, rising in response to inflammation, infection, or tissue injury.

Most plasma proteins are synthesized by the liver, though immunoglobulins are produced by plasma cells in the bone marrow and lymphoid tissues. Plasma proteins contribute to immune defense, transport of minerals, vitamins, and hormones, and the regulation of blood volume and coagulation. Clinically, plasma protein levels are assessed via total protein tests and serum protein electrophoresis. Abnormal levels can indicate liver or kidney disease, malnutrition, dehydration, or immune disorders, including monoclonal gammopathies that alter the pattern of protein fractions.