title: Effect of a Limited Iodine Diet on Iodine Uptake by Thyroid Glands in Hyperthyroid Cats.
abstract: BACKGROUND
  The effect of feeding a limited iodine diet on radioactive iodine uptake in the thyroid glands of hyperthyroid cats is unknown.
  
  
  OBJECTIVE
  To determine how feeding limited dietary iodine affects radioactive iodine uptake by the thyroid glands of hyperthyroid cats.
  
  
  METHODS
  Eight geriatric cats with spontaneous hyperthyroidism.
  
  
  METHODS
  Prospective study of eight client owned hyperthyroid cats fed a commercially available iodine limited diet for 6 months. Clinical signs were evaluated and TT4 and fT4 were measured during consumption of the diet. Uptake of (123)I was determined before and 8-16 weeks after exclusive consumption of the diet.
  
  
  RESULTS
  Clinical signs of hyperthyroidism resolved in all cats, but there was no significant increase in body weight. TT4 and fT4 decreased into the reference range by 8-16 weeks in all cats. Mean TT4 before consumption of the diet was 9.7 μg/dL (SD 5.2) and after consumption of the diet was 3.1 μg/dL (SD 0.9). Scintigraphy revealed unilateral uptake of isotope in 5 cats and bilateral uptake in 3 cats. Mean percentage uptake of (123)I by the thyroid gland at 8 hours after isotope administration was 16.2 (SD 11.8) before diet consumption and 34.6 (SD 11.7) 8-16 weeks after exclusive consumption of the diet. The percentage increase was variable between cats (38-639%).
  
  
  CONCLUSIONS
  Limited iodine diets increase iodine uptake in the autonomous thyroid glands of hyperthyroid cats. Further studies are necessary to determine if consumption of a limited iodine diet changes sensitivity of the thyroid gland to (131)I treatment.
authors: Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN.
authors: J C
authors: JC
authors: Scott-Moncrieff
authors: Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN.
authors: H G
authors: HG
authors: Heng
authors: Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, West Lafayette, IN.
authors: H Y
authors: HY
authors: Weng
authors: Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN.
authors: D
authors: D
authors: Dimeo
authors: Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN.
authors: M D
authors: MD
authors: Jones
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000000981:diagnostic imaging / Q000178:diet therapy*; D002415:Cats; D005260:Female; D006980:Hyperthyroidism / Q000000981:diagnostic imaging / Q000178:diet therapy / Q000662:veterinary*; D007455:Iodine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D049268:Positron-Emission Tomography / Q000662:veterinary; D011446:Prospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood
chemical_list: D007457:Iodine Radioisotopes; D007455:Iodine; D013974:Thyroxine
keywords: 123Iodine; 131Iodine; Nuclear scintigraphy; Thyroid hormone; Thyroxine