The thyroid stimulating hormone (TSH) stimulation test has been used to assess thyroid reserve in studies of hypothyroid dogs, however limited data are available for cats. The purpose of this study was to assess the effect of mild to moderate concurrent illness on the response of euthyroid cats to the TSH stimulation test.
This was a prospective study of 35 client-owned and shelter-housed mature adult cats. A full examination including systolic blood pressure, routine hematology, biochemistry and urinalysis, measurement of urine protein-creatinine ratio, total thyroxine (tT4), free thyroxine (fT4) and TSH, and a TSH stimulation test were performed. Cats thought to be 7 years or older were recruited, however the age of shelter cats could not always be verified. Hospitalized cats and cats receiving thyroid-suppressive medications were excluded. Cats were divided into 3 groups based on their physical examination and laboratory results: group 0 (no concurrent illness detected), group 1 (mild concurrent illness e.g. moderate dental disease or stable IRIS stage II chronic kidney disease) and group 2 (moderate concurrent illness e.g. untreated moderate to severe hypertension, anemia, hypoalbuminemia, proteinuria and/or hypokalemia). Results are reported as median (range). Post-TSH tT4 concentrations (post-tT4) and the ratio of tT4 concentrations before and after TSH administration (tT4 ratio) were compared between the 3 groups using the Kruskal Wallis H-test.
Twelve cats were owned and 23 cats were shelter-housed. Two shelter-housed cats were diagnosed with hyperthyroidism and excluded from further evaluation. In the remaining 33 cats, baseline tT4 was 25.9nmol/l (17.2-39.3), post-tT4 was 64.4nmol/l (29.4-102) and tT4 ratio was 2.41 (1.56-3.95). There was no significant difference (p > 0.05) in post-tT4 or tT4 ratio between the 3 groups (group 0, n=8; group 1, n=16; group 2, n=9), therefore no effect of mild-moderate illness on the TSH stimulation test results in this study.
Douglas College, British Columbia, Canada
Dr. Jennifer Wakeling graduated from Cambridge University (U.K.) in 1992 with a 1st class honours degree in Zoology, and from Cambridge University Veterinary School, top of her class for Veterinary Medicine, in 1995. In 1999 she was awarded a Certificate in Small Animal Medicine by the Royal College of Veterinary Surgeons (U.K.). After 8 years in primary care clinical practice Dr. Wakeling returned to academia at the Royal Veterinary College (London) to study for her Ph.D. in feline hyperthyroidism under the tutelage of Dr. Harriet Syme and Prof. Jonathan Elliott which resulted in peer-reviewed publications on subclinical hyperthyroidism, diagnosis of hyperthyroidism, a questionnaire based study of risk factors for the development of hyperthyoidism and a study of urinary iodine excretion in hyperthyroid cats. The Ph.D. entitled "The Aetiopathogenesis of Feline Hyperthyroidism" was successfully defended and awarded in 2008.
Since moving to Vancouver, B.C. (Canada) in 2007 Dr Wakeling has worked as Medical Director of a large small animal hospital (2008-2012) and more recently as a faculty instructor in the Douglas College Veterinary Technology program (2012- present). In 2014 she was awarded an Applied Research and Development grant by the Canadian Natural Sciences and Engineering Research Council (NSERC) for a 3 year study of iatrogenic hypothyroidism in radio-iodine treated cats.
Thursday, June 14
11:30 AM – 11:45 AM
Thursday, June 14
11:45 AM – 12:00 PM
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