Renal tubular dysfunction in primary Sjögren's syndrome: clinical studies in 27 patients

Kidney involvement in Sjögren's syndrome (SS) including renal tubular disorders are well recognized but little is known about frequency and extent of such dysfunction in the general population of patients with primary SS, due to a lack of group studies. We studied 27 patients with primary SS and without other possible causes of tubular dysfunction. Increased urinary beta 2M excretion, due to proximal tubular dysfunction, was present in 26% of patients. Inadequate urine acidification after oral NH4 Cl, proving distal tubular dysfunction, was found in 12% of the patients studied. Concentrating ability, tested by thirst, was decreased in 44% of patients studied. Abnormal renal tubular tests correlated with presence of ANA (p = 0.05) but not with other clinical parameters. In conclusion demonstrable renal tubular dysfunctions occur in over half the patients with primary SS. Literature concerning this subject is discussed.