Serum pepsinogen I in rheumatic diseases. Reduced levels in Sjögren's syndrome.

Group I pepsinogens were measured by radioimmunoassay in the sera of 93 patients with rheumatic diseases and 99 controls. Patients with rheumatoid arthritis and systemic lupus erythematosus had levels of pepsinogen I similar to controls, whereas patients with Sjögren's syndrome had levels significantly lower than either controls (P less than 0.001) or patients with rheumatic diseases not associated with sicca syndrome (P less than 0.001). The concentrations of serum pepsinogen I were lower in patients with sicca syndrome alone than in those with sicca syndrome associated with some other connective tissue disease (P less than 0.05). In patients with Sjögren's syndrome, a negative correlation was found between serum concentrations of beta 2-microglobulin and pepsinogen I (r = -0.46, P less than 0.05).