Research Communications of the 24th ECVIM-CA Congress

Median serum concentrations of total T4 (11.6 nmol/L; reference interval [RI], 10-50 nmol/L), T3 (0.6 nmol/L; RI, 0.5-0.8 nmol/L), and FT4 (15 pmol/L; RI, 10-50 pmol/L) were all in the low end of the RI. Normal RI values for T4 and FT4 were maintained in 22 (63%) and 30 (86%) of the cats, respectively. Serum cTSH values were high in all cats (median, 3.3 ng/dl; range, 0.47-12.0 ng/dl; RI, 0.03-0.30 ng/ml). Thyroid scintigraphy showed less-than-normal amounts of residual tissue, as well as low values for thyroid-to-salivary ratio and %-uptake of pertechnetate, in 30 (86%). Of those 5 cats with normal scintiscans, serum cTSH decreased into the RI without treatment when retested 1-6 months later.