2015 ACVIM Forum Research Abstract Program

Mark Peterson 1 , Jade Guterl 1 , Rhett Nichols 2 , Mark Rishniw 3 . 1 Animal Endocrine Clinic, New York, New York, USA, 2 Antech Diagnostics, Lake Success, New York, USA, 3 College of Veterinary Medicine, Cornell University, Ithaca, New York, USA In human patients, measurement of serum TSH is commonly used as a first-line discriminatory test of thyroid function, even before evaluation of serum T4, T3, or free T4 (FT4). Recent reports indicate that the canine TSH assay (Immulite Canine TSH, Siemens) can be used to measure feline TSH, and that this may be used to help diagnose or exclude hyperthyroidism in cats suspected of having the disease. Because high circulating T4 suppresses TSH secretion, serum TSH levels should be low in hyperthyroid cats, possibly even before serum T4 or free T4 are clearly elevated. Some have suggested that finding a measurable cTSH in a hyperthyroid cat is so unlikely that this alone can be used to rule out this disease.