Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (999 page)

   IgA makes up the majority of immunoglobulin in mucosal secretions, including nasal and pulmonary secretions, saliva and intestinal fluids, tears, and secretions of the genitourinary tract. IgA is important in preventing attachment or penetration of the body surfaces by microorganisms, and in protection against respiratory, GI, and GU infections. IgA cannot cross the placenta. It can be produced by infants, and their secretions tend to be typically low. IgA is the second most frequent type of monoclonal immunoglobulin identified in multiple myeloma.

   
Normal ranges:
see Table 16.41.

TABLE 16–41. Normal Ranges for IgA by Age

   Use

   Detection or monitoring of monoclonal gammopathies and immune deficiencies

   Assist in the diagnosis of multiple myeloma

   Monitor therapy for multiple myeloma

   Evaluate patients suspected of IgA deficiency prior to transfusion

   Evaluate anaphylaxis associated with the transfusion of blood and blood products (anti-IgA antibodies may develop in patients with low levels of IgA, possibly resulting in anaphylaxis when donated blood is transfused)

   Interpretation

Increased In

   Polyclonal:

   Cirrhosis of the liver

   Chronic infections