title: Phosphate salivary secretion in hemodialysis patients: implications for the treatment of hyperphosphatemia.
abstract: OBJECTIVE
  Hyperphosphatemia is recognized as contributing to the increased risk of cardiac death in end-stage renal disease (ESRD) and hemodialysis (HD) patients. Currently available pharmacologic treatment for hyperphosphatemia is based on phosphate binders but, despite treatment, only half of the patients fall within the range for serum phosphorus of the K/DOQI guidelines. Therefore, there is a need to identify other therapeutic approaches in order to reduce serum phosphate. Salivary fluid contains phosphate which, if related to the daily salivary secretion (1,000-1,880 ml), may raise interest in order to identify further additive approaches to phosphorus removal in uremic patients, while data about salivary phosphate secretion in ESRD patients are controversial.
  
  
  METHODS
  This study evaluates salivary phosphate secretion in 68 HD patients compared with 30 healthy subjects. Saxon's test confirmed normal salivary function in patients and controls. Salivary calcium and serum phosphate, calcium and PTH were also measured.
  
  
  RESULTS
  HD patients had significantly higher salivary phosphorus levels compared with healthy controls: 30.35 (26.5-34.6) vs. 12.1 (10.58-14.73) mg/dl (p < 0.0001), and this significantly correlated (p < 0.0001) with serum phosphorus. Multiple regression analysis confirmed serum phosphorus as the only predictor (p < 0.0001) of salivary phosphorus.
  
  
  CONCLUSIONS
  Given the functional secretive similarity between salivary glands and the kidneys, this increased salivary phosphate secretion might be interpreted as being compensatory in the presence of renal failure. Absorption of the increased salivary phosphate secretion, however, may worsen hyperphosphatemia; therefore, the binding of salivary phosphate might be considered as a further therapeutic approach to hyperphosphatemia in ESRD.
authors.affiliation: Department of Nephrology, University of Messina, Messina, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Savica
authors.forename: Lorenzo A
authors.initials: LA
authors.lastname: Calò
authors.forename: Renato
authors.initials: R
authors.lastname: Caldarera
authors.forename: Adelaide
authors.initials: A
authors.lastname: Cavaleri
authors.forename: Antonio
authors.initials: A
authors.lastname: Granata
authors.forename: Domenico
authors.initials: D
authors.lastname: Santoro
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Savica
authors.forename: Ugo
authors.initials: U
authors.lastname: Muraca
authors.forename: Agostino
authors.initials: A
authors.lastname: Mallamace
authors.forename: Guido
authors.initials: G
authors.lastname: Bellinghieri
mesh_terms: D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000378:metabolism* / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis*; D010760:Phosphorus Metabolism Disorders / Q000209:etiology / Q000378:metabolism* / Q000628:therapy*; D006435:Renal Dialysis; D012463:Saliva / Q000737:chemistry*
chemical_list: D010710:Phosphates