serumprotein

Serum protein refers to the collection of proteins present in blood serum, the liquid portion that remains after blood has clotted and been separated from cells. In healthy individuals, serum proteins are dominated by albumin and a group of globulins. Fibrinogen and most other clotting factors are absent in serum because they are consumed during clot formation.

Composition and major components

Albumin, the most abundant serum protein, helps maintain colloid osmotic pressure and serves as a carrier for fatty acids, hormones, and certain drugs. Globulins include alpha, beta, and gamma fractions. Immunoglobulins (antibodies) belong to the gamma globulins and play a central role in immune defense. Other globulins include transport proteins, enzymes, and components of the complement system. Unlike plasma, serum lacks fibrinogen and most coagulation factors.

Synthesis and turnover

Most serum proteins are synthesized in the liver, with immunoglobulins produced by plasma cells derived from B lymphocytes. Protein levels reflect a balance among dietary intake, liver function, kidney function, and immune activity, as well as acute or chronic inflammatory states.

Clinical relevance

Total serum protein and its fractions are measured to assess nutritional status, liver function, kidney function, and immune status. Typical healthy adults have a total serum protein of roughly 6–8 g/dL, with albumin around 3.5–5 g/dL and globulins comprising the remainder. Hypoproteinemia can cause edema and reflect malnutrition, liver disease, or protein loss (e.g., nephrotic syndrome or enteropathy). Hyperproteinemia may occur with dehydration, inflammation, or monoclonal gammopathies. Serum protein electrophoresis separates proteins into fractions (albumin, alpha-1, alpha-2, beta, gamma) to help identify abnormalities such as monoclonal proteins or immune deficiencies.

Specimen considerations

Specimens are typically drawn for chemistry panels or electrophoresis, with attention to avoiding hemolysis and ensuring proper handling for accurate measurements.