Renal tubular dysfunction in patients with primary Sjögren syndrome

Primary Sjögren's syndrome (pSS) is an important cause of renal tubular dysfunction in adults, mainly due to acquired type 1 distal renal tubular acidosis (RTA 1) and concentration defects (CD). This cross-sectional study evaluated renal tubular function of patients with pSS, by detecting proximal tubular injury (through measurements of urinary β2 microglobulin and albumin), RTA 1 (through an acidification protocol using furosemide and fludrocortisone), and CD (through water deprivation test, WDT). A total of 25 patients with pSS were evaluated and despite a preserved renal function (eGFR 92.5 ± 26.3 mL/min/1.73 m(2)), 24% were diagnosed as RTA 1. On the other hand, CD was diagnosed in 28% of the patients who presented worse renal function (eGFR 68.6 ± 27.7 mL/min/1.73 m(2)). Increased β2 microglobulin was found in 16% of the patients, and all of them had impaired renal function (eGFR 39.5 ± 11.9 mL/min/1.73 m(2)). These data showed a high prevalence of tubular dysfunction, mainly RTA 1 and CD, in patients with pSS, and suggest that patients with this disorder should be evaluated by the acidification protocol used in this study and WDT for proper diagnosis. Proximal tubular injury was less common, and probably associated with worsening of renal function.