title: Vitamin D Metabolites and Their Association with Calcium, Phosphorus, and PTH Concentrations, Severity of Illness, and Mortality in Hospitalized Equine Neonates.
abstract: BACKGROUND
  Hypocalcemia is a frequent abnormality that has been associated with disease severity and outcome in hospitalized foals. However, the pathogenesis of equine neonatal hypocalcemia is poorly understood. Hypovitaminosis D in critically ill people has been linked to hypocalcemia and mortality; however, information on vitamin D metabolites and their association with clinical findings and outcome in critically ill foals is lacking. The goal of this study was to determine the prevalence of vitamin D deficiency (hypovitaminosis D) and its association with serum calcium, phosphorus, and parathyroid hormone (PTH) concentrations, disease severity, and mortality in hospitalized newborn foals.
  
  
  RESULTS
  One hundred newborn foals ≤72 hours old divided into hospitalized (n = 83; 59 septic, 24 sick non-septic [SNS]) and healthy (n = 17) groups were included. Blood samples were collected on admission to measure serum 25-hydroxyvitamin D3 [25(OH)D3], 1,25-dihydroxyvitamin D3 [1,25(OH) 2D3], and PTH concentrations. Data were analyzed by nonparametric methods and univariate logistic regression. The prevalence of hypovitaminosis D [defined as 25(OH)D3 <9.51 ng/mL] was 63% for hospitalized, 64% for septic, and 63% for SNS foals. Serum 25(OH)D3 and 1,25(OH) 2D3 concentrations were significantly lower in septic and SNS compared to healthy foals (P<0.0001; P = 0.037). Septic foals had significantly lower calcium and higher phosphorus and PTH concentrations than healthy and SNS foals (P<0.05). In hospitalized and septic foals, low 1,25(OH)2D3 concentrations were associated with increased PTH but not with calcium or phosphorus concentrations. Septic foals with 25(OH)D3 <9.51 ng/mL and 1,25(OH) 2D3 <7.09 pmol/L were more likely to die (OR=3.62; 95% CI = 1.1-12.40; OR = 5.41; 95% CI = 1.19-24.52, respectively).
  
  
  CONCLUSIONS
  Low 25(OH)D3 and 1,25(OH)2D3 concentrations are associated with disease severity and mortality in hospitalized foals. Vitamin D deficiency may contribute to a pro-inflammatory state in equine perinatal diseases. Hypocalcemia and hyperphosphatemia together with decreased 1,25(OH)2D3 but increased PTH concentrations in septic foals indicates that PTH resistance may be associated with the development of these abnormalities.
authors.affiliation: College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America; Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Kamr
authors.affiliation: College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Dembek
authors.affiliation: Rood and Riddle Equine Hospital, Lexington, Kentucky, United States of America.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Reed
authors.affiliation: Hagyard Equine Medical Institute, Lexington, Kentucky, United States of America.
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Slovis
authors.affiliation: Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Zaghawa
authors.affiliation: College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Rosol
authors.affiliation: College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Ramiro E
authors.initials: RE
authors.lastname: Toribio
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood*; D006734:Horse Diseases / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D006736:Horses; D054559:Hyperphosphatemia / Q000453:epidemiology / Q000401:mortality / Q000473:pathology; D006996:Hypocalcemia / Q000453:epidemiology / Q000401:mortality / Q000473:pathology; D016015:Logistic Models; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood*; D012720:Severity of Illness Index; D014807:Vitamin D / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000453:epidemiology / Q000401:mortality / Q000473:pathology*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; D010758:Phosphorus; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium