title: Prevalence of distal renal tubular acidosis in primary Sjögren's syndrome.
abstract: OBJECTIVE
  Our objectives were to analyse the prevalence of distal renal tubular acidosis (dRTA) in primary SS (pSS) and to compare a novel urinary acidification test with furosemide and fludrocortisone (FF) with the gold standard ammonium chloride (NH4Cl) to detect dRTA.
  
  
  METHODS
  Urinary acidification was assessed in 57 pSS patients using NH4Cl and FF. A urinary acidification defect was defined as an inability to reach a urinary pH of <5.3 after NH4Cl.
  
  
  RESULTS
  The prevalence of complete dRTA (urinary acidification defect with acidosis) was 5% (3/57). All three patients had positive SSA/Ro and SSB/La autoantibodies and impaired kidney function. The prevalence of incomplete dRTA (urinary acidification defect without acidosis) was 25% (14/57). Compared with patients without dRTA, patients with incomplete dRTA had significantly lower venous pH and serum bicarbonate and higher urinary pH. SSB/La antibodies were more prevalent in the dRTA groups (P < 0.05). Compared with NH4Cl, the positive and negative predictive values of FF were 46% and 82%, respectively. Vomiting occurred more often during the urinary acidification test with NH4Cl than with FF (9 vs 0, P < 0.05).
  
  
  CONCLUSIONS
  Incomplete dRTA is common in pSS and causes mild acidaemia and higher urinary pH, which may contribute to bone demineralization and kidney stone formation. FF cannot replace NH4Cl in testing urinary acidification in pSS, but may be considered as a screening tool, given its reasonable negative predictive value and better tolerability.
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands t.both.1@erasmusmc.nl.
authors.forename: Tim
authors.initials: T
authors.lastname: Both
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ewout J
authors.initials: EJ
authors.lastname: Hoorn
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Robert
authors.initials: R
authors.lastname: Zietse
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Jan A M
authors.initials: JA
authors.lastname: van Laar
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Virgil A S H
authors.initials: VA
authors.lastname: Dalm
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Zana
authors.initials: Z
authors.lastname: Brkic
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Marjan A
authors.initials: MA
authors.lastname: Versnel
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.affiliation: Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands Division of Clinical Immunology and Division of Nephrology and Transplantation, Department of Internal Medicine and Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Paul L A
authors.initials: PL
authors.lastname: van Daele
mesh_terms: D000141:Acidosis, Renal Tubular / Q000175:diagnosis* / Q000453:epidemiology* / Q000276:immunology; D000368:Aged; D000643:Ammonium Chloride; D000974:Antibodies, Antinuclear / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005438:Fludrocortisone; D005665:Furosemide; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D015995:Prevalence; D012859:Sjogren's Syndrome / Q000150:complications*
chemical_list: D000974:Antibodies, Antinuclear; C035356:SS-A antibodies; C035357:SS-B antibodies; D000643:Ammonium Chloride; D005665:Furosemide; D005438:Fludrocortisone
keywords: ammonium chloride; fludrocortisone; furosemide; pH; urinary acidification