What is Hyperthyroidism?
Hyperthyroidism (also known an overactive thyroid) occurs when the thyroid gland produces excessive thyroid hormones. This causes many of the body's functions to speed up. About 2 in 100 women, and 2 in 1000 men, develop hyperthyroidism at some stage of their life.
Treatment of Overactive Thyroid
Three forms of treatment are available for hyperthyroidism. Each of them have their own advantages and limitations and physicians prefer one over the other due to reasons of simplicity, cost and availability and also on the severity of hyperthyroidism, existing illnesses and the age of patient. Each of the possible treatments for an overactive thyroid have some advantages and some disadvantages. In general, all three treatments are highly effective and associated with a low risk of side effects.
Drug Therapy
Drug therapy includes the use of beta-blocking agents and antithyroid drugs.
Antithyroid Drugs (ATD)
Most patients with hyperthyroidism are given antithyroid drugs as initial therapy. There are two main antithyroid drugs available for use in the United States: methimazole (Tapazole) and propylthiouracil (PTU). They interfere with the ability of the thyroid gland to synthesize its hormones and are usually given in high doses until the thyroid gland functions normally (becomes euthyroid). This can take one to two months. PTU is preferred in pregnant hyperthyroid patients.
Indications and Benefits:
- availability and simplicity
- ATD drugs work well to control the overactive thyroid, bring prompt control of hyperthyroidism, and do not cause permanent damage to the thyroid gland
- may be used for long-term treatment of Graves' disease.
- PTU is preferred choice in pregnant women with overactive thyroid
- preferred treatment by many endocrinologists for children and for adults who refuse radioactive iodine
- pretreatment of older and cardiac patients before radioactive iodine or surgery
- both medications (methimazole and PTU) considered safe for use while breastfeeding
Disadvantages, Risks and Possible Side Effects:
- High relapse rate (relapse is more likely in smokers, patients with large goiters, and patients with positive thyroid-stimulating antibody levels at the end of therapy). Hyperthyroid condition returns in about half of all patients.
- PTU can cause elevated liver enzymes, and immunoallergic hepatitis
- Methimazole can cause rare cholestasis and rare congenital abnormalities
- Minor side effects include rash, fever, gastrointestinal effects, and arthralgia
- Rare side effect is called "agranulocytosis". This is a condition in which the white blood cells, which fight infection, disappear from the body. This could be a serious problem if an infection developed while those white blood cells were low. Fortunately, there is usually a warning when you get agranulocytosis - a fever and a sore throat. Patients on antithyroid drugs who develop a fever and a sore throat should stop the pills and call right away to get a blood test. If the blood test shows agranulocytosis, patients must remain off the antithyroid drugs. The white blood cells usually return to normal within one to two weeks.
Beta-blocker Medicines
There are medications available to immediately treat the symptoms caused by excessive thyroid hormones, such as a rapid heart rate. One of the main classes of drugs used to treat these symptoms is the beta-blockers (e.g., Inderal, Tenormin, Lopressor). Some people take a beta-blocker medicine for a few weeks whilst the level of thyroxine is reduced gradually by one of the available treatments.
Indications and Benefits:
- Prompt relief of the adrenergic symptoms of hyperthyroidism such as tremor, palpitations, heat intolerance, and nervousness.
- Treatment of choice for thyroiditis
- First line therapy before surgery, radioactive iodine, and antithyroid drugs
- Short term therapy in pregnancy
Disadvantages, Risks and Possible Side Effects:
- Must be used with caution in older patients and in patients with pre-existing heart disease, chronic obstructive pulmonary disease, or asthma.
Radioactive Iodine (Radioiodine)
The thyroid cells are the only cells in the body that are able to absorb iodine. By giving radioactive iodine, cells in the thyroid are damaged or destroyed and are unable to produce further thyroid hormone. Radioiodine therapy involves taking a drink, or swallowing a capsule, which contains radioactive iodine. The dose of radioactivity to the rest of the body is very low and is not dangerous.
Indications and Benefits:
- Inexpensive, highly effective, easy to administer, and safe
- High cure rates with single-dose treatment (80%)
- Treatment of choice for Graves' disease, multinodular goiter, toxic nodules in patients older than 40 years, and relapses from antithyroid drugs
Disadvantages, Risks and Possible Side Effects:
- Delayed control of symptoms
- Posttreatment hypothyroidism in majority of patients with Graves' disease regardless of dosage
- Contraindicated in patients who are pregnant or breastfeeding
- Can cause transient neck soreness, flushing, and decreased taste
- Radiation thyroiditis in 1% of patients
- May exacerbate Graves' ophthalmopathy
- May require pretreatment with antithyroid drugs in older or cardiac patients
- Treatment of hyperthyroidism in children remains controversial
- Reluctance to use in women of childbearing years
Surgery
In a situation where radioiodine is not available and the patient is not responding to ATD patients are subjected to a surgery. Surgery (thyroidectomy) involves removing part of the thyroid gland. It may be a good option if you have a large goitre (thyroid swelling) which is causing problems in the neck. If too much of the thyroid is removed it is not usually a problem as you can take thyroxine tablets to keep the thyroxine level normal. It is usually a safe operation, although as with all operations there is a small risk. This mode of treatment requires 5-10 days of hospitalization.
Indications and Benefits:
- Treatment of choice for people:
- with very large goiters
- who cannot tolerate antithyroid medicine or fail antithyroid drugs
- who refuse radioactive iodine treatment
- who have opthalmopathy (staring/bulging eyes)
- young women and contemplating pregnancy
- with severe disease who could not tolerate recurrence
- May be done for cosmetic reasons
Disadvantages, Risks and Possible Side Effects:
- Higher morbidity and cost than radioactive iodine
- Risk of hypothyroidism or hyperthyroid relapse
- Temporary or permanent hypoparathyroidism or laryngeal paralysis
- Requires patient to be euthyroid preoperatively with antithyroid drugs or iodides to avoid thyrotoxic crisis
