Increased serum immunoglobulin concentrations occur due to polyclonal or oligoclonal immunoglobulin proliferation in hepatic disease (hepatitis, liver cirrhosis), connective tissue diseases, acute and chronic infections, as well as in the cord blood of neonates with intra uterine and perinatal infections. Elevations of IgG, IgA, or IgM may occur in monoclonal gammopathies such as multiple myeloma (IgG, IgA), macroglobulinemia (IgM), primary systemic amyloidosis, monoclonal gammopathy of undetermined significance (MGUS), and related disorders. Decreased levels are found in patients with primary or secondary immune deficiencies.
Immunotypings are done to determine monoclonal specificity, or to rule out a monoclonal gammopathy. Monoclonal gammopathies are characterized by an uncontrolled proliferation of a single clone of plasma cells at the expense of other clones. This often leads to the synthesis of large amounts of one immunoglobulin with decreased levels of normal immunoglobulins. Plasma cell myeloma, along with decreased levels of normal immunoglobulins can lead to life threatening consequences. Light chain disease, where only kappa and lambda monoclonal light chains are synthesized, may also lead to suppression of normal immunoglobulins. These low molecular weight immunoglobulin fragments are filtered through the glomerulus of the kidney and into the urine, giving a serum electrophoresis pattern showing hypogammaglobulinemia, with a faint monoclonal band or no band at all in the serum.