The influence of a single ethanol injection on normal thyroid tissue of the rat.

Macro- and microscopic changes in the normal thyroid gland of rats, and in the surrounding tissues 2 and 4 weeks after a single intrathyroidal ethanol injection (IEI), together with the influence of such treatment on the function of the recurrent laryngeal nerves and of the parathyroid glands, were assessed. The intraoperative macroscopic evaluation at 2 weeks (20 rats) and 4 weeks (20 rats) after IEI revealed the presence of a scar at the site of the IEI-treated lobe in seven (35%) and six (30%) rats, respectively, and the reduction of lobe dimensions in thirteen (65%) and fourteen (70%) rats, respectively. The microscopic evaluation of the lobe after IEI showed coagulative necrosis, reduction in thyroid follicle volume, disturbance of follicle structure, haemorrhage, haemosiderin deposits, inflammatory infiltration and fibrosis. No microscopic changes were observed in the tissues surrounding the thyroid, nor in the parathyroid glands located extrathyroidally or in the second thyroid lobe. No vocal cord dysfunction or significant changes in serum calcium levels after IEI were detected.