25 Jul
In normal serum, about 80% is immunoglobulin G (IgG).
Elevations of IgG may be due to polyclonal or monoclonal immunoglobulin production. Monoclonal elevations of IgG characterize monoclonal gammopathies such as multiple myeloma, primary systemic amyloidosis, monoclonal gammopathy of undetermined significance, and related disorders. Monoclonal gammopathies may lead to a spike in the gamma globulin zone seen on serum protein electrophoresis.
Decreased immunoglobulin levels are found in patients with primary or secondary immune deficiencies.