INFLUENCE OF SYSTEMIC NONTHYROIDAL ILLNESS ON SERUM CONCENTRATION OF THYROXINE IN HYPERTHYROID CATS

One-hundred and ten hyperthyroid cats were evaluated for additional sy stemic nonthyroidal illness retrospectively. The effect of systemic no nthyroidal illness on serum T4 concentrations was evaluated. Systemic nonthyroidal illness was diagnosed in 35.5% of the hyperthyroid cats e valuated (39/110). Serum T4 concentrations were significantly decrease d in hyperthyroid cats with systemic nonthyroidal illness when compare d to hyperthyroid cats with no other clinically significant disease id entified. Normal serum T4 concentrations were observed in only 12.7% ( 14/110) of the hyperthyroid cats. Systemic nonthyroidal illnesses were diagnosed in 11 of the 14 hyperthyroid cats with normal serum concent rations of T4.