title: Serum Cystatin C Concentrations in Cats with Hyperthyroidism and Chronic Kidney Disease.
abstract: BACKGROUND
  Currently, no test can accurately predict the development of azotemia after treatment of hyperthyroidism. Serum cystatin C concentrations (sCysC) might be less influenced by changes in body muscle mass and so better indicate the presence of concurrent chronic kidney disease (CKD) in hyperthyroidism.
  
  
  OBJECTIVE
  sCysC will be higher in hyperthyroid cats that develop azotemia compared with hyperthyroid cats that remain nonazotemic after treatment; sCysC will be higher in nonhyperthyroid cats with azotemic CKD than healthy older cats and, sCysC will decrease after treatment of hyperthyroidism.
  
  
  METHODS
  Ninety-one cats treated in first opinion practice.
  
  
  METHODS
  Case-control study. sCysC were compared between hyperthyroid cats which developed azotemia within 4 months of successful treatment of hyperthyroidism (pre-azotemic group) and hyperthyroid cats which remained nonazotemic after treatment (nonazotemic group), and between nonhyperthyroid cats with azotemic CKD and healthy older cats. sCysC were also compared between hyperthyroid cats before treatment and at time of establishment of euthyroidism. Data are presented as median [25th, 75th percentile].
  
  
  RESULTS
  Baseline sCysC were not different between the pre-azotemic and nonazotemic groups (1.9 [1.4, 2.3] mg/L versus 1.5 [1.1, 2.2] mg/L, respectively; P = .22). sCysC in nonhyperthyroid cats with azotemic CKD and healthy older cats were not significantly different (1.5 [1.0, 1.9] mg/L versus 1.2 [0.8, 1.4] mg/L, respectively; P = .16). sCysC did not change significantly after treatment of hyperthyroidism (pretreatment 1.8 [1.2, 2.3] mg/L, after treatment 1.6 [1.1, 2.4] mg/L; P = .82).
  
  
  CONCLUSIONS
  sCysC do not appear to be a reliable marker of renal function in hyperthyroid cats.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
authors.forename: T L
authors.initials: TL
authors.lastname: Williams
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
authors.forename: H
authors.initials: H
authors.lastname: Dillon
authors.affiliation: Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Elliott
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, Hatfield, UK.
authors.forename: H M
authors.initials: HM
authors.lastname: Syme
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
authors.forename: J
authors.initials: J
authors.lastname: Archer
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood*; D016022:Case-Control Studies; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D002415:Cats; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006980:Hyperthyroidism / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*; D008297:Male; D009391:Nephelometry and Turbidimetry / Q000662:veterinary; D011237:Predictive Value of Tests; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*
chemical_list: D015415:Biomarkers; D055316:Cystatin C
keywords: Azotemia; Clinical chemistry; Clinical pathology; Endocrinology; Renal function; Thyroid; Urinary tract; Validation