Abstract
To clarify the prevalence of subclinical renal tubular acidosis (RTA) and its association with clinical and laboratory parameters in primary and secondary Sjögren's syndrome (SS), an acid-loading test was conducted. Subclinical RTA was found in 32% of patients with SS. The prevalence of subclinical RTA in primary and secondary SS was about the same (31.6% and 33.3%, respectively). Significant longer duration of illness, more severely decreased salivary excretion, decreased lymphocyte number, higher serum levels of IgG and IgA, and higher frequency of anti-SS-A (Ro) and SS-B (La) antibodies were found in patients with subclinical RTA. These results suggested that subclinical RTA may be a characteristic manifestation both in primary and secondary SS, along with the progression of immunologic dysfunction, when the illness seemed to be indolent.