Interpretation

Elevated levels of IgM occur with early acute infections since this is the first antibody to appear with the immune response. Elevated levels may also be found with inflammatory reactions, autoimmune states (eg, rheumatoid arthritis) or monoclonal gammopathies (eg, Waldenstrom macroglobulinemia). Neonatal elevations of IgM occur in association with intrauterine infection such as rubella, syphilis, cytomegalovirus infection and others. Decreased levels of IgM is the second most common hypogammaglobulinemia. Most frequently, the deficiency is secondary to more serious underlying illness and selective IgM deficiency with normal levels of the other immunoglobulins is fairly rare. Clinically, IgM deficiency is manifested by recurrent infections, including sudden overwhelming sepsis. Other associated disorders include splenomegaly, atopy, and hemolytic anemia. The differential diagnosis includes Wiskott Aldrich syndrome, in which IgM deficiency is a regular feature. The cause of primary (selective) IgM deficiency is not known. See Additional Information below also.