A case report of macroamylasemia with rheumatoid arthritis

A patient of rheumatoid arthritis complicated with macroamylasemia. Serum amylase level was persistently elevated without any apparent cause. Amylase creatine clearance ratio was reduced inspite of normal renal function. These findings suggested the presence of macroamylasemia. The abnormal molecular size of amylase isozyme was electrophoresed. Thin layer chromatography and electroimmunosyneresis revealed that the amylase binding molecule was immunoglobulin (IgA kappa type). The etiology and the clinical significance of the macroamylasemia remain unclear. Amylase binding immunoglobulin is thought to be autoantibody to amylase. Thus, the association with autoimmune diseases is suggested. However, only few cases have been reported of autoimmune diseases complicated with macroamylasemia. In this case, macroamylase appeared about 10 months after the onset of RA. Serum amylase level was inconsistent during the clinical course. Further follow-up study is considered to be important.