title: Saliva urea dipstick test: application in chronic kidney disease.
abstract: BACKGROUND
  A noninvasive test for determining elevated levels of blood urea nitrogen (BUN) may be useful under circumstances in which there is limited access to laboratories. Because saliva urea nitrogen (SUN) parallels BUN, we investigated the diagnostic performance of a semiquantitative SUN dipstick to test for elevated BUN levels in patients with chronic kidney disease (CKD).
  
  
  METHODS
  Patients with CKD Stages 1 to 5D were studied. 50 µl of saliva were transferred onto the SUN test strip (Integrated Biomedical Technology, Elkhart, Indiana, IN, USA). SUN was determined after 1 minute by visual comparison of the color of the moistened test pad with 6 calibrated color blocks. Interobserver reproducibility was evaluated by independent observers, masked to urea concentrations of 6 calibrated urea solutions. Correlation between SUN and BUN was quantified by Spearman's rank correlation coefficient (RS), Kappa Statistic was employed to evaluate within-sample reproducibility of duplicates. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance of SUN.
  
  
  RESULTS
  68 patients (31 females, 60 ± 14 years; 34 hemodialysis patients, 34 patients CKD Stages 1 - 4) were studied. Interobserver coefficient of variation was 4.9% at SUN levels > 50 mg/dl; within-sample reproducibility was 90%. SUN and BUN were correlated significantly (RS = 0.63; p < 0.01). Elevated BUN was diagnosed with high accuracy by SUN determination (area under the ROC curve: 0.90 (95% CI 0.85 - 0.95)).
  
  
  CONCLUSIONS
  Semiquantitative dipstick measurements of SUN can reliably identify CKD patients with elevated BUN levels.
authors: Renal Research Institute, New York City, NY 10128, USA. j-raimann@gmx.net
authors: J G
authors: JG
authors: Raimann
authors: W
authors: W
authors: Kirisits
authors: E
authors: E
authors: Gebetsroither
authors: M
authors: M
authors: Carter
authors: J
authors: J
authors: Callegari
authors: L
authors: L
authors: Rosales
authors: N W
authors: NW
authors: Levin
authors: P
authors: P
authors: Kotanko
mesh_terms: D001806:Blood Urea Nitrogen; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D011934:Reagent Strips; D012463:Saliva / Q000737:chemistry*; D014508:Urea / Q000032:analysis*
chemical_list: D011934:Reagent Strips; D014508:Urea