title: Association of Vitamin D Metabolites with Parathyroid Hormone, Fibroblast Growth Factor-23, Calcium, and Phosphorus in Dogs with Various Stages of Chronic Kidney Disease.
abstract: BACKGROUND
  Hypovitaminosis D is associated with progression of renal disease, development of renal secondary hyperparathyroidism (RHPT), chronic kidney disease-mineral bone disorder (CKD-MBD), and increased mortality in people with CKD. Despite what is known regarding vitamin D dysregulation in humans with CKD, little is known about vitamin D metabolism in dogs with CKD.
  
  
  OBJECTIVE
  The purpose of our study was to further elucidate vitamin D status in dogs with different stages of CKD and to relate it to factors that affect the development of CKD-MBD, including parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), calcium, and phosphorus concentrations.
  
  
  METHODS
  Thirty-seven dogs with naturally occurring CKD were compared to 10 healthy dogs. Serum 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)2D], and 24,25-dihydroxyvitamin D [24,25(OH)2D], and PTH and FGF-23 concentrations were measured. Their association with serum calcium and phosphorus concentrations and IRIS stage was determined.
  
  
  RESULTS
  Compared to healthy dogs, all vitamin D metabolite concentrations were significantly lower in dogs with International Renal Interest Society (IRIS) stages 3 and 4 CKD (r [creatinine]: -0.49 to -0.60; P < .05) but not different in dogs with stages 1 and 2 CKD. All vitamin D metabolites were negatively correlated with PTH, FGF-23, and phosphorus concentrations (r: -0.39 to -0.64; P < .01).
  
  
  CONCLUSIONS
  CKD in dogs is associated with decreases in all vitamin D metabolites evaluated suggesting that multiple mechanisms, in addition to decreased renal mass, affect their metabolism. This information could have prognostic and therapeutic implications.
authors.affiliation: Veterinary Clinical Sciences, The Ohio State University, Columbus, OH.
authors.forename: V J
authors.initials: VJ
authors.lastname: Parker
authors.affiliation: Veterinary Clinical Sciences, The Ohio State University, Columbus, OH.
authors.forename: L M
authors.initials: LM
authors.lastname: Harjes
authors.affiliation: Veterinary Clinical Sciences, The Ohio State University, Columbus, OH.
authors.forename: K
authors.initials: K
authors.lastname: Dembek
authors.affiliation: Center for Biostatistics, The Ohio State University, Columbus, OH.
authors.forename: G S
authors.initials: GS
authors.lastname: Young
authors.affiliation: Veterinary Clinical Sciences, The Ohio State University, Columbus, OH.
authors.forename: D J
authors.initials: DJ
authors.lastname: Chew
authors.affiliation: Veterinary Clinical Sciences, The Ohio State University, Columbus, OH.
authors.forename: R E
authors.initials: RE
authors.lastname: Toribio
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood*; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood*; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000662:veterinary*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D010758:Phosphorus; D005346:Fibroblast Growth Factors; C097949:1,25-dihydroxyvitamin D; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D; D003404:Creatinine; D002118:Calcium
keywords: calcitriol; diet; international renal interest society; renal secondary hyperparathyroidism