title: Comparison of serum parathyroid hormone and ionized calcium and magnesium concentrations and fractional urinary clearance of calcium and phosphorus in healthy horses and horses with enterocolitis.
abstract: OBJECTIVE
  To evaluate calcium balance and parathyroid gland function in healthy horses and horses with enterocolitis and compare results of an immunochemiluminometric assay (ICMA) with those of an immunoradiometric assay (IRMA) for determination of serum intact parathyroid hormone (PTH) concentrations in horses.
  
  
  METHODS
  64 horses with enterocolitis and 62 healthy horses.
  
  
  METHODS
  Blood and urine samples were collected for determination of serum total calcium, ionized calcium (Ca2+) and magnesium (Mg2+), phosphorus, BUN, total protein, creatinine, albumin, and PTH concentrations, venous blood gases, and fractional urinary clearance of calcium (FCa) and phosphorus (FP). Serum concentrations of PTH were measured in 40 horses by use of both the IRMA and ICMA.
  
  
  RESULTS
  Most (48/64; 75%) horses with enterocolitis had decreased serum total calcium, Ca2+, and Mg2+ concentrations and increased phosphorus concentrations, compared with healthy horses. Serum PTH concentration was increased in most (36/51; 70.6%) horses with hypocalcemia. In addition, FCa was significantly decreased and FP significantly increased in horses with enterocolitis, compared with healthy horses. Results of ICMA were in agreement with results of IRMA.
  
  
  CONCLUSIONS
  Enterocolitis in horses is often associated with hypocalcemia; 79.7% of affected horses had ionized hypocalcemia. Because FCa was low, it is unlikely that renal calcium loss was the cause of hypocalcemia. Serum PTH concentrations varied in horses with enterocolitis and concomitant hypocalcemia. However, we believe low PTH concentration in some hypocalcemic horses may be the result of impaired parathyroid gland function.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus 43210, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Toribio
authors.forename: C W
authors.initials: CW
authors.lastname: Kohn
authors.forename: D J
authors.initials: DJ
authors.lastname: Chew
authors.forename: R A
authors.initials: RA
authors.lastname: Sams
authors.forename: T J
authors.initials: TJ
authors.lastname: Rosol
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood* / Q000652:urine; D004760:Enterocolitis / Q000097:blood / Q000652:urine / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000378:metabolism* / Q000652:urine; D006736:Horses; D006996:Hypocalcemia / Q000097:blood / Q000652:urine / Q000662:veterinary; D015592:Immunoradiometric Assay / Q000662:veterinary; D008163:Luminescent Measurements; D008274:Magnesium / Q000097:blood*; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000652:urine*; D018709:Statistics, Nonparametric
chemical_list: D010281:Parathyroid Hormone; D010758:Phosphorus; D008274:Magnesium; D002118:Calcium