2015 ACVIM Forum Research Abstract Program

In conclusion, serum TSH concentrations are suppressed in over 98% of hyperthyroid cats, but values are indeed measurable in a few cats with mild to moderate hyperthyroidism. Although most clinically normal cats and euthyroid cats suspected of having thyroid disease will have detectable TSH concentrations, about 40% of the euthyroid cats in this study also had serum concentrations that were below the level of quantification. Overall, serum TSH determination represents a highly sensitive but poorly specific test for diagnosis of feline hyperthyroidism when used in combination with T4 and FT4 determinations. Radioiodine ( 131 I) is an effective treatment for feline hyperthyroidism, but optimal dosing to restore euthyroidism without inducing hypothyroidism remains unclear. Post-treatment hypothyroidism can lead to azotemia and reduced survival.