Plasmaproteiini

Plasmaproteiini refers to the group of proteins found in blood plasma. The major fractions are albumin, globulins (alpha, beta, and gamma), and fibrinogen, together with a variety of smaller proteins such as transporters, enzymes, enzymes inhibitors, and acute-phase reactants. Albumin constitutes the largest portion of plasma proteins, while gamma globulins largely consist of immunoglobulins produced by B cells and plasma cells.

Most plasmaproteins are synthesized in the liver; albumin and many transport and coagulation proteins are liver-derived, whereas immunoglobulins are produced by plasma cells of the immune system. Fibrinogen is a key precursor of fibrin in the blood-clotting cascade. Plasma proteins serve diverse roles, including maintaining colloid osmotic pressure, transporting hormones, fatty acids, bilirubin, and drugs, supporting immune defense, and participating in coagulation and inflammation.

Measurement and clinical relevance: the total plasma protein concentration in adults is typically about 60–80 g/L. Albumin accounts for roughly 35–50 g/L, while globulins make up the remaining 20–30 g/L; the albumin–globulin ratio is commonly assessed in laboratory tests. Electrophoretic separation or specific immunoassays can quantify individual fractions and identify abnormalities.

Disorders involving plasmaproteins include hypoalbuminemia, which can cause edema and is seen in liver disease, nephrotic syndrome, and malnutrition; hypo- or hyperglobulinemia can reflect immune disorders or chronic inflammation. Increased gamma globulins occur in conditions such as multiple myeloma or chronic infections, whereas fibrinogen deficiencies increase bleeding risk. Plasma proteins also bind and transport many drugs, influencing pharmacokinetics.