title: The occurrence of renal involvement in primary Sjögren's syndrome: a study of 78 patients.
abstract: OBJECTIVE
  To ascertain the occurrence of renal involvement in patients with primary Sjögren's syndrome (pSS).
  
  
  METHODS
  Urinary total protein excretion from 24 h urine collection, as well as urinary excretion rates of albumin, alpha-1 microglobulin (alpha1m) and IgG from overnight 8 h collections, were determined from 78 pSS patients (75 females, three males). Urine acidification capacity after oral ammonium chloride load was tested in 55 of these patients.
  
  
  RESULTS
  Mild proteinuria (0.15-0.42 g/24 h) was observed in 34 patients (44%). Increased urinary excretion rates of albumin (>/=20 microgram/min), alpha1m (>/=7.0 microgram/min) or IgG (>/=5.0 microgram/min) were detected in nine (12%), nine (12%) and 11 patients (14%), respectively. Latent or overt distal renal tubular acidosis (dRTA) was observed in 18 out of 55 patients with pSS (33%). These patients had a longer duration of the disease (10+/-4 vs 8+/-4 yr; P</=0.05); they also had proteinuria (67 vs 27%; P</=0.025) and hypertension (44 vs 14%; P</=0.05) more frequently, and significantly higher serum creatinine (92+/-39 vs 78+/-13 micromol/l; P</=0.025) and serum beta-2 microglobulin (beta2m) levels (3.3+/-1.6 g/l vs 2.6+/-0. 6 g/l; P</=0.025) as compared to patients with normal urine acidification capacity.
  
  
  CONCLUSIONS
  Inadequate renal acidification capacity, as well as mild proteinuria, were frequently found in patients with pSS. Those with dRTA had longer disease duration, a higher level of serum beta2m, and they had proteinuria and hypertension more frequently than those with normal renal acidification capacity.
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, University of Tampere, Tampere, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Pertovaara
authors.forename: M
authors.initials: M
authors.lastname: Korpela
authors.forename: T
authors.initials: T
authors.lastname: Kouri
authors.forename: A
authors.initials: A
authors.lastname: Pasternack
mesh_terms: D000141:Acidosis, Renal Tubular; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000643:Ammonium Chloride / Q000378:metabolism; D005260:Female; D006801:Humans; D007669:Kidney Calculi; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011507:Proteinuria; D012859:Sjogren's Syndrome / Q000378:metabolism / Q000503:physiopathology*; D016482:Urinalysis; D014552:Urinary Tract Infections
chemical_list: D000643:Ammonium Chloride