Chemical analysis of whole saliva in Sjögren's syndrome.

In some studies, but not in all, abnormally high concentrations of salivary Na+, K+, and IgA have been found in patients with Sjögren's syndrome (SS). The lack of agreement between various reports might be due to the different ways in which saliva was collected. Some analysed stimulated parotid or whole saliva, whereas others used unstimulated saliva. In this study, therefore, the rate of flow and Na+, K+, and IgA levels in unstimulated and stimulated whole saliva in normals and in rheumatoids with and without SS have been determined. The results confirmed significantly raised levels of Na+, K+, and IgA in unstimulated whole saliva in SS. In response to stimulation there was marked decrease in Na+, K+, and IgA levels, whereas normally, as shown by the other two groups, there is an increase in Na+, no change in K+, and a mild decrease in IgA. As a result, the differences between SS and normals became much less significant (K+, IgA) or were even completely obliterated (Na+). The abnormal response of SS to stimulation may be partially explained by the initially low rate of flow and by the extremely high IgA levels. Thus chemical analysis of unstimulated whole saliva is much more sensitive than analysis of stimulated whole saliva in the detection of salivary gland involvement in SS.