title: Renin-angiotensin-aldosterone system activity in hyperthyroid cats with and without concurrent hypertension.
abstract: BACKGROUND
  Hypertension is present in some hyperthyroid cats at diagnosis or can develop after treatment for hyperthyroidism. Activation of the renin-angiotensin-aldosterone system (RAAS) could be involved in the pathogenesis of hypertension.
  
  
  OBJECTIVE
  Hyperthyroid cats that develop hypertension before or after treatment for hyperthyroidism will have greater RAAS activation than normotensive cats.
  
  
  METHODS
  Ninety-nine hyperthyroid cats.
  
  
  METHODS
  Retrospective case-control study. Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in untreated hyperthyroid hypertensive cats (HT-Pre group), initially normotensive hyperthyroid cats that develop hypertension after treatment (HT-Post group), and hyperthyroid cats that are normotensive (NT group). Data are presented as median [25th, 75th percentile].
  
  
  RESULTS
  Baseline PRA was not significantly different among the 3 groups (HT-Pre group 1.50 [0.05, 2.37] ng/mL/h, HT-Post group 0.66 [0.17, 2.31] ng/mL/h, NT group 1.11 [0.57, 2.18] ng/mL/h; P = .44). PRA decreased significantly after treatment in the NT group (1.09 [0.53, 2.47] versus 0.22 [0.05, 0.76] ng/mL/h; P < .001) and the HT-Post group (0.71 [0.17, 2.33] versus 0.28 [0.07, 0.57] ng/mL/h; P = .006). Baseline PAC was not significantly different among the 3 groups (HT-Pre group 72.2 [40.0, 145.6] pg/mL, HT-Post group 69.7 [43.3, 142.6] pg/mL, NT group 109.0 [68.2, 184.6] pg/mL; P = .10). PAC decreased significantly after treatment in the NT group (114.4 [56.6, 204.1] versus 59.5 [32.4, 98.2] pg/mL; P < .001) but did not change significantly in the HT-Post group (61.2 [44.9, 124.0] versus 58.4 [42.0, 97.7] pg/mL; P = .59).
  
  
  CONCLUSIONS
  RAAS activation occurs in hyperthyroid cats, but is not associated with the development of hypertension. PAC is not influenced by changes in PRA in hyperthyroid cats that develop hypertension after treatment, perhaps indicating RAAS dysfunction in these cats.
authors.affiliation: Department of Veterinary Clinical Sciences, Royal Veterinary College, North Mymms, UK. timwilliams@cantab.net
authors.forename: T L
authors.initials: TL
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Elliott
authors.forename: H M
authors.initials: HM
authors.lastname: Syme
mesh_terms: D000818:Animals; D016022:Case-Control Studies; D002371:Cat Diseases / Q000209:etiology / Q000473:pathology*; D002415:Cats; D005260:Female; D006973:Hypertension / Q000662:veterinary*; D006980:Hyperthyroidism / Q000150:complications / Q000378:metabolism / Q000662:veterinary*; D008297:Male; D012084:Renin-Angiotensin System / Q000502:physiology*; D012189:Retrospective Studies