title: Leptin and ghrelin concentration in hyperthyroid cats before and after radioactive iodine therapy compared to euthyroid control cats.
abstract: OBJECTIVE
  Leptin and ghrelin, two peptide hormones with antagonistic effects on satiety and energy balance, could be involved in the pathogenesis of weight loss and polyphagia in cats with hyperthyroidism. Leptin generally decreases appetite and increases energy expenditure, while ghrelin exerts the opposite effects.
  
  
  METHODS
  Leptin and ghrelin were measured in 42 client owned hyperthyroid cats with a body condition score (BCS) ≤ 5/9 before (T0) and 4 weeks after radioactive iodine treatment (RAIT) (T1). Dependent on the serum total thyroxine concentration concentration at T1, cats were sub-classified as still hyperthyroid (ht-ht) (n = 4), euthyroid (ht-eu) (n = 10) or hypothyroid (ht-hypo) (n = 28). Results were compared to those of 22 healthy, euthyroid control cats with a comparable BCS (≤ 5/9) and age (≥ 8 years) to hyperthyroid cats.
  
  
  RESULTS
  At T0, there were no significant differences between hyperthyroid and control cats for leptin (p = 0.06) or ghrelin concentrations (p = 0.27). At T1, leptin significantly decreased in ht-hypo cats compared to T0 (p = 0.0008) despite a significantly increased body weight in this group (p = 0.0001). Serum ghrelin concentrations did not differ between hyperthyroid cats with a history of polyphagia compared to non-polyphagic cats (p = 0.42). After RAIT, ghrelin concentration significantly increased in all hyperthyroid cats (p < 0.0001), as well as in the subgroups ht-eu (p = 0.014) and ht-hypo (p < 0.0001) compared to their respective T0 baseline concentrations.
  
  
  CONCLUSIONS
  Leptin and ghrelin fluctuations may be indicative of changes in metabolic functions in cats with thyroid dysfunction. Leptin fluctuations occurred independently of body weight in different states of thyroid dysfunction; increasing ghrelin concentrations after RAIT suggest a ghrelin-independent mechanism for polyphagia in hyperthyroid cats.
authors.affiliation: Sina Marsilio, Gastrointestinal Laboratory, Department of Small Animal Clinical Science, Texas A&M University, 4474 TAMU, College Station, TX 77843-4474, USA, Email: SMarsilio@cvm.tamu.edu.
authors.forename: Sina
authors.initials: S
authors.lastname: Marsilio
authors.forename: Barbara
authors.initials: B
authors.lastname: Glanemann
authors.forename: Lucile
authors.initials: L
authors.lastname: Martin
authors.forename: Balazs
authors.initials: B
authors.lastname: Szladovits
authors.forename: Reto
authors.initials: R
authors.lastname: Neiger
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000097:blood* / Q000532:radiotherapy*; D002415:Cats; D054439:Ghrelin / Q000097:blood*; D006980:Hyperthyroidism / Q000097:blood / Q000532:radiotherapy / Q000662:veterinary*; D007037:Hypothyroidism / Q000097:blood / Q000532:radiotherapy / Q000662:veterinary; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D020738:Leptin / Q000097:blood*
chemical_list: D054439:Ghrelin; D007457:Iodine Radioisotopes; D020738:Leptin
keywords: Thyroid dysfunction; feline; thyroid hormones