title: Evaluation of predictors for the diagnosis of hyperthyroidism in cats.
abstract: BACKGROUND
  In humans, subclinical hyperthyroidism is diagnosed when serum thyroid hormone concentrations are within the reference range but thyroid stimulating hormone (TSH) concentration is subnormal. In a previous study, a higher prevalence of thyroid nodular disease was found in euthyroid geriatric cats with undetectable TSH (<0.03 ng/mL) compared to those with detectable TSH concentrations, suggesting subclinical hyperthyroidism might also exist in cats.
  
  
  OBJECTIVE
  Euthyroid cats with undetectable TSH concentrations have subclinical hyperthyroidism and may subsequently develop overt signs of hyperthyroidism.
  
  
  METHODS
  One-hundred four client-owned cats.
  
  
  METHODS
  In this prospective cohort study, euthyroid geriatric (≥ 9 years) cats were recruited during routine health checks. Plasma biochemistry was performed at baseline and every 6 months thereafter. Total thyroxine and TSH concentrations were determined annually. Short-term follow-up data (within 14 months of recruitment) were used to detect variables at entry that were predictive of the diagnosis of hyperthyroidism, using univariable analysis followed by multivariable logistic regression analysis. Log rank analysis was used to test the association of initial TSH concentration with diagnosis of hyperthyroidism during the total available follow-up.
  
  
  CONCLUSIONS
  Median (range) follow-up was 26 (0-54) months and annual incidence of hyperthyroidism during the study was 7.4%. Cats that became hyperthyroid within 14 months had higher ALKP activity (P = 0.02) and higher prevalence of goiter (P = .03) at baseline than controls. Cats with undetectable TSH at baseline (29/104; 28%) were significantly (P < .001) more likely to be diagnosed with hyperthyroidism. However, not all cats with undetectable TSH became hyperthyroid during the study.
authors: Royal Veterinary College, London, UK. jenniferwakeling@gmail.com
authors: Jennifer
authors: J
authors: Wakeling
authors: Jonathan
authors: J
authors: Elliott
authors: Harriet
authors: H
authors: Syme
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis*; D002415:Cats; D005260:Female; D006980:Hyperthyroidism / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors
chemical_list: D013972:Thyrotropin; D013974:Thyroxine