FRI0166 HIGH FREQUENCY OF KIDNEY STONES AND/OR NEPHROCALCINOSIS IN PRIMARY SJOGREN’S SYNDROME MIGHT ACCELERATE CHRONIC RENAL DYSFUNCTION DUE TO TUBULOINTERSTITIAL DISEASE

Abstract

Background:The renal involvement of primary Sjögren’s syndrome (pSS) is characterized by distal renal tubular acidosis (RTA), tubulointerstitial nephritis (TIN), and/or glomerulonephritis [1,2]. Kidney stones and nephrocalcinosis are presumably caused by subclinical distal tubular acidosis, but its clinical significance has not been clarified.Objectives:This study aimed to clarify the frequency and clinical features of patients with pSS with kidney stones and/or nephrocalcinosis.Methods:We examined 59 patients with anti SS-A/Ro positive pSS who underwent abdominal computed tomography and/or ultrasound between 1998 and 2019 at Kanazawa University Hospital. We identified 2 groups of patients with primary Sjögren’s syndrome: 1) patients with kidney stones and/or nephrocalcinosis (group A: n=19) and 2) those without kidney stones and/or nephrocalcinosis (group B: n=40), and retrospectively analyzed their clinical features.Results:Kidney stones and/or nephrocalcinosis were confirmed in 19 of 59 (32%) patients with pSS. The patients comprised 4 males and 55 females with an average age of 60 years (range, 30 to 83 years) and mean observation period of 96 months (range 1 to 336 months). Estimated glomerular filtration rate (eGFR) at the time of diagnostic imaging (group A vs group B: 71.5 ml/min/1.73 m2vs 82.8 ml/min/1.73 m2; p=0.37) and eGFR at last follow up (group A vs group B: 59.3 ml/min/1.73 m2vs 74.7 ml/min/1.73 m2;p=0.03) of group A were lower than those of group B and urinary β2-microgloblin (group A vs group B: 7222 μg/mL vs 437 μg/mL; p=0.01) and urinary N-acetyl-β-D-glucosaminidase (group A vs group B: 5.8 U/L vs 3.9 U/L; p=0.22) of group A were higher than those of group B, while serum electrolytes (sodium, potassium, chloride, calcium, phosphorus), fractional excretion of calcium (group A vs group B: 1.2% vs1.5%; p=0.916), ESSDAI (group A vs group B: 7.6 vs 4.3; p=0.069), and eGFR decrease rate were not significantly different.Conclusion:32% patients with anti SS-A/Ro positive pSS had kidney stones and/or nephrocalcinosis in our cohort and their presence might accelerate chronic renal dysfunction due to tubulointerstitial disease (subclinical RTA or TIN).