What is the thyroid gland?
The thyroid is a hormone-producing gland located in the neck just below the laryngeal node. It secretes two thyroid hormones, T3 and T4, in the blood.
What is the function of thyroid hormones?
The liver converts most of the T4 into the more biologically active T3, which circulates in the blood and enters almost every cell in the body, regulating cellular metabolism (energy expenditure).
What is hyperthyroidism?
Hyperthyroidism, also known as thyrotoxicosis, is a condition in which the thyroid gland becomes overactive and thus produces too much thyroid hormone in the bloodstream.
What are the symptoms of hyperthyroidism?
Typical symptoms of hyperthyroidism usually include: fatigue, irritability, nervousness, tremors, fear of heat, excessive sweating, palpitations, weight loss, diarrhea, and muscle weakness.
What causes hyperthyroidism?
There are many causes of hyperthyroidism, including: Graves’ disease, toxic nodular goiter, toxic single nodule, postpartum thyroiditis, subacute thyroiditis, subclinical thyroiditis, and oral overdose of thyroxine.
What is Graves’ disease?
Graves’ disease is an autoimmune disease and is the most common type of hyperthyroidism. This specific antibody stimulates the thyroid gland to proliferate and secrete large amounts of thyroid hormones.
What are toxic nodular goiter and toxic individual nodules?
The thyroid gland tends to form nodules for unknown reasons. When there are multiple nodules, it is called a nodular goiter; if these nodules also secrete a lot of thyroxine in the bloodstream, it is called a toxic goiter; if there is only one nodule and it secretes a lot of thyroxine, it is called a toxic single nodule.
What is postpartum thyroiditis?
Postpartum thyroiditis is a diffuse enlargement of the thyroid gland immediately after delivery. The inflamed thyroid gland releases large amounts of thyroxine and causes hyperthyroidism.
How is hyperthyroidism diagnosed?
In hyperthyroidism, blood levels of T3 and T4 are elevated and levels of TSH, a hormone produced by the pituitary gland that stimulates the thyroid gland to synthesize thyroxine, are extremely low. When the thyroid is hyperactive, there is no need for TSH stimulation, so the pituitary gland stops synthesizing TSH.
What other tests are necessary to confirm a diagnosis of hyperthyroidism?
In most cases, a thyroid scan and iodine uptake measurement of the thyroid gland are necessary to determine the type of hyperthyroidism.
How is Graves’ disease treated?
Graves’ disease can be treated with medications, radioactive iodine, and surgery. Most patients are given medication first and then radioactive iodine if it does not work; other patients prefer radioactive iodine. Surgery is rarely used, but it is not a bad treatment option in special cases.
What drugs are used to treat Graves’ disease?
PTU (propylthiouracil) and Tapazole (tabazol) reduce thyroxine synthesis and are collectively known as antithyroid drugs. They usually reduce thyroxine levels to within the normal range within 4 to 6 weeks and also inhibit the function of cells that produce anti-self thyroid antibodies that cause Graves’ disease. About 20% to 40% of patients with Graves’ disease can be cured after taking any of these drugs for 6 to 18 months.
Rash is the most common complication of antithyroid drugs; rarely, it causes a moderate to severe decrease in the number of blood leukocytes (cells that fight inflammation); sometimes it can also cause liver damage. PTU is safer than Tapazole for pregnant patients.
What is the efficacy and safety of radioactive iodine in the treatment of Graves’ disease?
Radioactive iodine therapy can be the first choice for the treatment of Graves’ disease, but it can also be used after drug therapy has failed. Over 90% of patients with Graves’ disease are cured within 3-4 months after radioactive iodine treatment.
The main complication after radioactive iodine treatment is hypothyroidism (low thyroid function). It occurs in more than 50% of patients, depending on the dose of radioactive iodine given, and can occur at any time from three months after treatment to many years thereafter. Hypothyroidism can be easily treated with thyroxine replacement therapy after the onset of hypothyroidism.
Radioactive iodine has been used to treat hyperthyroidism since the early 1940s, and long-term follow-up of a large number of patients has shown that radioactive iodine treatment is not associated with a high incidence of infertility or cancer.
When is surgery used to treat Graves’ disease?
Surgery is rarely the treatment of choice for Graves’ disease, but it may be considered for extremely severe hyperthyroidism or for those who do not want to undergo radioactive iodine therapy.
The chance of surgery causing hypothyroidism is at least 50%, but thyroxine replacement therapy can be easily administered; other complications are rare and less than 5%, one of which is damage to the recurrent laryngeal nerve passing through the thyroid gland resulting in hoarseness, mostly temporary but sometimes permanent; surgery may also damage the parathyroid glands located next to the thyroid gland, resulting in lower calcium levels and the need to take calcium tablets or vitamin D to maintain normal blood levels. Calcium tablets or vitamin D are necessary to maintain normal blood calcium levels.
Will I gain weight after treatment for hyperthyroidism?
Patients who are treated for hyperthyroidism usually gain an average of 5 to 15 pounds, mainly because they change from a hyperthyroid state (high metabolism) to a normal or hypothyroid state (low metabolism) in a very short period of time. Close contact with your doctor will help to detect and treat hypothyroidism early. Once treated with thyroxine replacement therapy, the body’s metabolism will return to normal and weight gain will cease.
Is Graves’ disease hereditary?
Yes, that is, the risk of having a loved one with Graves’ disease is higher than normal, and the risk of having a family member with Hashimoto’s thyroiditis (which can cause hypothyroidism) is also increased.
How is toxic nodular goiter and toxic single nodules treated?
Antithyroid medications are not effective for toxic nodular goiter and toxic single nodules, but can sometimes be used to lower blood thyroxine levels. Radioactive iodine therapy and surgery are the mainstays of treatment for both diseases.
How is postpartum thyroiditis and other types of thyroiditis treated?
These diseases typically present with 2 to 3 months of hyperthyroidism followed by 2 to 3 months of hypothyroidism, and then resolve themselves. Treatment is usually not necessary, but if symptoms are severe then 9 threo-blockers may be given during the hyperthyroid phase and thyroxine replacement therapy during the hypothyroid phase.