title: The Effect of Moderate Dietary Protein and Phosphate Restriction on Calcium-Phosphate Homeostasis in Healthy Older Cats.
abstract: BACKGROUND
  Dietary phosphate and protein restriction decreases plasma PTH and FGF-23 concentrations and improves survival time in azotemic cats, but has not been examined in cats that are not azotemic.
  
  
  OBJECTIVE
  Feeding a moderately protein- and phosphate-restricted diet decreases PTH and FGF-23 in healthy older cats and thereby slows progression to azotemic CKD.
  
  
  METHODS
  A total of 54 healthy, client-owned cats (≥ 9 years).
  
  
  METHODS
  Prospective double-blinded randomized placebo-controlled trial. Cats were assigned to test diet (protein 76 g/Mcal and phosphate 1.6 g/Mcal) or control diet (protein 86 g/Mcal and phosphate 2.6 g/Mcal) and monitored for 18 months. Changes in variables over time and effect of diet were assessed by linear mixed models.
  
  
  RESULTS
  A total of 26 cats ate test diet and 28 cats ate control diet. There was a significant effect of diet on urinary fractional excretion of phosphate (P = 0.045), plasma PTH (P = 0.005), and ionized calcium concentrations (P = 0.018), but not plasma phosphate, FGF-23, or creatinine concentrations. Plasma PTH concentrations did not significantly change in cats fed the test diet (P = 0.62) but increased over time in cats fed the control diet (P = 0.001). There was no significant treatment effect of the test diet on development of azotemic CKD (3 of 26 (12%) test versus 3 of 28 (11%) control, odds ratio 1.09 (95% CI 0.13-8.94), P = 0.92).
  
  
  CONCLUSIONS
  Feeding a moderately protein- and phosphate-restricted diet has effects on calcium-phosphate homeostasis in healthy older cats and is well tolerated. This might have an impact on renal function and could be useful in early chronic kidney disease.
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hatfield, UK. rgeddes@rvc.ac.uk.
authors.forename: R F
authors.initials: RF
authors.lastname: Geddes
authors.affiliation: Royal Canin SAS, Aimargues, France.
authors.forename: V
authors.initials: V
authors.lastname: Biourge
authors.affiliation: Department of Comparative Biological Sciences, Royal Veterinary College, Camden, London, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hatfield, UK.
authors.forename: H M
authors.initials: HM
authors.lastname: Syme
authors.affiliation: Department of Comparative Biological Sciences, Royal Veterinary College, Camden, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Elliott
mesh_terms: D000375:Aging / Q000502:physiology; D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002415:Cats / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D004044:Dietary Proteins / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology*; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism; D010710:Phosphates / Q000008:administration & dosage* / Q000378:metabolism
chemical_list: D004044:Dietary Proteins; D010281:Parathyroid Hormone; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002118:Calcium
keywords: 
  CKD
  ; 
  PTH
  ; FGF-23; Feline; Nutrition; Renal/Urinary tract