Functional Effects of Short-Term Treatment with Amiodarone on Thyroid Tissues of the Rabbit

The effect of short-term treatment with Amiodarone on thyroid gland tissue was studied in a group of 26 New Zealand albino rabbits. Ten rabbits were left untreated and served as controls; the remaining animals were treated with 10 mg/kg/day Amiodarone. The serum levels of serum triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) levels were measured at days 0 (baseline), 7, 30, and 45. The serum selenium levels were also measured, but only on days 0 and 45 of the experiment. At the end of the experiment the animals were sacrificed and the levels of selenium, T3, T4, and iodine were determined in thyroid tissue. After 30 days treatment the values of T3 were significantly lower than those of the untreated controls or the baseline levels (p < 0.001). The T4 level was significantly lower and the TSH value was significantly higher after 45 days of Amiodarone (p < 0.001). In thyroid tissue the T3, T4, and iodine levels were significantly higher in the treated group when compared to untreated controls (p < 0.05). These results show that Amiodarone induces changes in the hormone levels in both serum and thyroid tissues, as well as in the amount of iodine taken up by the thyroid gland in rabbits.