Globulin

DEFINITION
Heterogenous group of proteins; includes immunoglobulins, clotting factors, acute-phase proteins, and complement proteins
Hyperglobulinemia—high serum globulin concentration
Hypoglobulinemia—low serum globulin concentration
Gammopathy—any abnormality in the concentration of immunoglobulins

PATHOPHYSIOLOGY
Hyperglobulinemia—from increased production of immunoglobulins and hepatic synthesis of acute-phase proteins; falsely increased by dehydration; classified as either polyclonal or monoclonal; may result in hyperviscosity syndrome and impaired immune function
Polyclonal gammopathies—from production of immunoglobulins by several different cell lines; usually in response to persistent antigenic stimulation
Monoclonal gammopathies—from synthesis of one type of immunoglobulin by a single clone of cells; proliferation may be associated with lymphoid hyperplasia or neoplasia.
Hypoglobulinemia—from either impaired synthesis or extracorporeal globulin loss
Impaired synthesis—results in immunodeficiency syndromes; characterized by chronic infection and unthrifty appearance
Extracorporeal loss—commonly from gastrointestinal disease; also secondary to blood loss; rarely from hepatic insufficiency and renal losses