Serum isoamylases in patients with autoimmune rheumatic diseases.

We studied sera of 107 patients with autoimmune rheumatic diseases (46 with classical rheumatoid arthritis (RA), 36 with systemic lupus erythematosus (SLE) and 25 with primary Sjögren's syndrome (SS). None of these patients had abdominal pain or gastrointestinal symptoms at the time of blood collection. We used as controls 81 normal age and sex matched volunteers. The presence of hyperamylasemia i) of P-type in 6 of 46 patients (13%) with RA and ii) of P-type and S-type in 11 of 36 patients (30.5%) with SLE and 6 of the 25 patients (24%) with primary SS suggests that asymptomatic pancreatic damage in autoimmune rheumatic diseases may occur frequently especially in patients with SLE. We conclude that the hyperamylasemia in these patients probably reflects a slow, subclinical, inflammatory process of the exocrine glands.