title: Abnormalities of serum electrolyte concentrations in dogs with hypoadrenocorticism.
abstract: BACKGROUND
  The sensitivity and specificity of the sodium to potassium ratio (Na:K ratio) as a cutoff for recommendation of an adrenocorticotropic hormone (ACTH) stimulation test in dogs suspected of having hypoadrenocorticism (HA) is unknown. Additionally, abnormalities in plasma ionized calcium (iCa2+) and ionized magnesium (iMg2+) concentrations and venous pH of dogs with HA are incompletely documented.
  
  
  OBJECTIVE
  To define the sensitivity and specificity of the Na:K ratio as a diagnostic aid for HA in dogs and to examine for associations between venous pH and the Na:K ratio, iCa2+ concentration, or iMg2+ concentration in dogs with HA.
  
  
  METHODS
  Seventy-six dogs with HA and 200 dogs randomly selected from the general hospital population.
  
  
  METHODS
  Retrospective study. Dogs were included in the study if results of an ACTH stimulation test confirmed a diagnosis of HA, the dog had a serum sodium concentration below the reference range or a serum potassium concentration above the reference range, and the dog was treated with mineralocorticoids. Receiver operating curve analysis was used to determine optimal cutoffs of sensitivity and specificity for the Na:K ratio in diagnosing HA.
  
  
  RESULTS
  Use of Na:K ratios of 27 or 28 classified 95% of dogs correctly as diseased or not diseased. The sensitivity of a Na:K ratio of 28 was 93% (CI, 85-98%) and that of 27 was 89% (CI, 80-95%). The specificity of a Na:K ratio of 28 was 96% (CI, 92-98%) and that of 27 was 97% (CI, 93- 99%). The sensitivity and specificity of a Na:K ratio of 24 were 79% (95% CI, 67-86%) and 100% (98%, CI, 97%-100%), respectively.
  
  
  CONCLUSIONS
  Na:K ratios of 27 or 28 identify the highest percentage of dogs with suspected mineralocorticoid and glucocorticoid deficiency correctly. In dogs with a Na:K ratio of 24 or less, the likelihood of confirming a diagnosis of HA with an ACTH stimulation test is high.
authors.affiliation: Department of Clinical Studies, Matthew J. Ryan Veterinary Hospital, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Adler
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Drobatz
authors.forename: Rebecka S
authors.initials: RS
authors.lastname: Hess
mesh_terms: D000308:Adrenocortical Hyperfunction / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D000818:Animals; D001774:Blood Chemical Analysis; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs; D004573:Electrolytes / Q000097:blood*; D011188:Potassium / Q000097:blood*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012964:Sodium / Q000097:blood*
chemical_list: D004573:Electrolytes; D012964:Sodium; D011188:Potassium