The use of medications and radioactive iodine has made surgery for hyperthyroidism much less common. Surgery involves removing diseased parts of the thyroid gland through an open incision in the neck. Complications of thyroid surgery may include damage to the nerves that supply the vocal cords, infection, and damage to the parathyroid glands (four tiny glands in the thyroid tissue that regulate calcium levels in the body). If a total thyroidectomy is performed all of the thyroid tissue is removed and the patient will need to be maintained on thyroid replacement therapy for the rest of their life.
Thyroid hormones enter cells through membrane transporter proteins. A number of plasma membrane transporters have been identified, some of which require ATP hydrolysis; the relative importance of different carrier systems is not yet clear and may differ among tissues. Once inside the nucleus, the hormone binds its receptor, and the hormone-receptor complex interacts with specific sequences of DNA in the promoters of responsive genes. The effect of the hormone-receptor complex binding to DNA is to modulate gene expression , either by stimulating or inhibiting transcription of specific genes.
If a person has too little thyroid stimulating hormone, it is most likely that their thyroid gland is making too much thyroid hormone, that is, they have an overactive thyroid or hyperthyroidism , which is suppressing the thyroid stimulating hormone. People with an overactive thyroid have the opposite symptoms to those with hypothyroidism, . they lose weight (despite increasing the amount they eat), feel too hot and can experience palpitations or anxiety. They may also have a slightly enlarged thyroid gland. Treatment is medication in the form of tablets, which reduce the activity of the thyroid gland and return all thyroid hormone levels to normal. Rarely, problems in the pituitary gland can also result in a low thyroid stimulating hormone, and low free thyroid hormone levels.