Globulin

Overview

Globulin measures the major class of serum proteins excluding albumin, comprising immunoglobulins, transport proteins (transferrin, haptoglobin), complement proteins, and acute phase reactants. Total globulin (total protein minus albumin) reflects immune function, liver synthetic capacity, and inflammatory status. Elevated levels indicate polyclonal gammopathy (chronic inflammation, infection, autoimmune disease), monoclonal gammopathy (multiple myeloma), or dehydration, while low levels suggest immunodeficiency, liver disease, or protein-losing enteropathy. Globulin fraction from serum protein electrophoresis is clinically useful for screening paraproteinemias and characterizing inflammatory states.

Clinical Use Cases

  • Screening for monoclonal gammopathies (multiple myeloma, Waldenström macroglobulinemia).
  • Evaluating polyclonal hypergammaglobulinemia in chronic liver disease or autoimmune disorders.
  • Assessing protein synthetic function in liver disease.
  • Monitoring malnutrition or protein-losing conditions.

Specimen Types

  • Serum.
  • Plasma (less common).

Measurement Methods

  • Biuret colorimetric total protein minus albumin (indirect calculation).
  • Serum protein electrophoresis (SPEP) for globulin fractions.
  • Immunonephelometry for specific globulin classes.

Test Preparation and Influencing Factors

  • No fasting required.
  • Dehydration concentrates globulins; overhydration dilutes.
  • Intravenous immune globulin or recent plasma transfusion elevates levels.
  • Monoclonal proteins may cause overestimation in some methods.

Synonyms

  • Serum globulins.
  • Gamma globulins (predominantly immunoglobulins).
  • Total globulin (by calculation).

Further Reading