Plasmaproteins

Plasmaproteins, or plasma proteins, are a diverse group of proteins present in blood plasma. They account for about 6-8% of plasma by weight and include major components such as albumin, globulins, and fibrinogen.

The main components are albumin, globulins, and fibrinogen. Albumin, the most abundant plasma protein, is produced by the liver and helps maintain oncotic pressure and transport various substances. Globulins are a broad group divided into alpha, beta, and gamma fractions and include transport proteins, enzymes, antibodies, and other immune-related proteins. Fibrinogen is a clotting factor essential for blood coagulation. Immunoglobulins (antibodies) are produced by plasma cells and are classed within the globulin group.

Functions of plasmaproteins are varied. Albumin regulates the distribution of body fluids and serves as a carrier for hormones, fatty acids, and drugs. Globulins participate in transport, enzymatic activity, and immune defense. Fibrinogen participates in clot formation, while other plasma proteins contribute to the complement system and immune responses. Acute-phase proteins, another subset of plasma proteins, rise during inflammation and infection.

Synthesis and distribution: most plasma proteins are synthesized in the liver, with notable exceptions such as immunoglobulins produced by B cells. Plasma proteins influence blood viscosity and acid-base balance and can act as buffers in the circulatory system.

Clinical aspects: levels are assessed by total protein measurements and serum protein electrophoresis. Abnormal levels can indicate liver disease, nephrotic syndrome, malnutrition, dehydration, inflammation, or monoclonal gammopathies. Hypoalbuminemia reflects reduced synthesis or loss of albumin, while hyperglobulinemia or monoclonal gammopathy suggests plasma cell disorders; abnormalities in fibrinogen relate to coagulation or inflammatory states.