Serum protein electrophoresis identifying a monoclonal gammopathy or decreased immunoglobulins suggests lymphoproliferative disorders or amyloidosis; diffuse hypergammaglobulinemia suggests chronic infection (eg, malaria, visceral leishmaniasis, brucellosis, tuberculosis), cirrhosis with congestive splenomegaly, sarcoidosis, or connective tissue disorders (eg, systemic lupus erythematosus, Felty syndrome in patients with rheumatoid arthritis).