(Science: procedure) surgery to remove part or all of the thyroid gland. This might be done to remove a tumour or treat hyperthyroidism or goiter (enlarged thyroid gland). The goal of surgery in hyperthyroidism is to remove just enough thyroid gland so that a normal amount of thyroid hormone is produced. If too much thyroid is removed, the patient will produce too little thyroid hormone (hypothyroidism) and need treatment to return the thyroid status to normal (euthyroid). The complications of surgery can include vocal cord paralysis and accidental removal of the parathyroid glands (located behind the thyroid gland), resulting in low calcium levels (the parathyroid glands regulate calcium).