Causes of paraproteinemia include the following:[citation needed] These are characterized by the presence of any abnormal protein that is involved in the immune system, which are most often immunoglobulins and are associated with the clonal proliferation of lymphocytes.

They are generally equal in proportion, but albumin is much smaller than globulin, and slightly negatively charged, which leads to an accumulation at the end of the electrophoretic gel.

[citation needed] It is also possible for paraproteins (usually whole immunoglobulins) to form polymers by aggregating with each other; this takes the name of macroglobulinemia and may lead to further complications.

Others may make blood too viscous to flow smoothly (usually with IgM pentamer macroglobulins), a phenomenon known as Waldenström macroglobulinemia.

[citation needed] The most common type of paraproteinemia is monoclonal gammopathy of undetermined significance (MGUS).