Serum isoamylases in Sjögren's syndrome. Concentration levels and intra-individual variation.

A study of isoamylase in serum from 53 patients with Sjögren's syndrome demonstrated that the levels of both pancreatic type and salivary type amylases remain within reference value limits in most cases. However, abnormal low or high values for pancreatic type amylases were seen more frequently than in the control groups. The intra-individual variation in concentration levels of both isoenzymes among patients with Sjögren's syndrome were significantly greater than in the control groups. These observations are interpreted as signs of subclinical lesions of the pancreas and the salivary glands occurring during the course of the disease. Sjögren's syndrome should be borne in mind and sought in cases of unexplained hypo- or hyperisoamylasemias.