Hyperthyroidism (cont.)
How is hyperthyroidism treated?
The options for treating hyperthyroidism include:
- Treating the symptoms
- Antithyroid drugs
- Radioactive iodine
- Surgery treating symptoms
Treating
the symptoms
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 [for example,
propranolol (Inderal),
atenolol (Tenormin),
metoprolol (Lopressor)].
These medications counteract the effect
of thyroid hormone to increase metabolism, but they do not
alter the levels of thyroid hormones in the blood. A doctor determines which patients
to treat based on a number of variables including the underlying cause
of hyperthyroidism, the age of the patient, the size of the thyroid gland,
and the presence of coexisting medical illnesses.
Antithyroid Drugs
There are two main antithyroid drugs available for use in the United States,
methimazole (Tapazole) and propylthiouracil (
PTU). These drugs accumulate in
the thyroid tissue and block production of thyroid hormones. PTU also blocks the conversion
of T4 hormone to the more metabolically active T3 hormone. The major risk
of
these medications is occasional suppression of production of white blood cells by
the bone marrow
(agranulocytosis). (White cells are needed to fight infection.) It is
impossible to tell if and when this side effect is going to occur, so regular determination
of white blood cells in the blood are not useful.
It is important for patients
to know that if they develop a fever, a sore throat, or any signs of infection
while taking methimazole or propylthiouracil, they should see a doctor immediately. While a
concern, the actual risk of developing agranulocytosis is less than 1%. In
general, patients should be seen by the doctor at monthly intervals while taking antithyroid
medication. The dose is adjusted to maintain the patient in as close to a normal
thyroid state as possible (euthyroid). Once the dosing is stable, patients
can be seen at three month intervals if long-term therapy is planned.
Usually, long-term antithyroid therapy is only used for patients with Graves'
disease, since this disease may actually go into remission under
treatment without requiring treatment with thyroid radiation or surgery.
If treated from one to two years, the data shows remission rates of 40%-70%. When the disease
is in remission, the gland is no longer overactive, and antithyroid medication is
not needed.
Recent studies also have shown that adding a pill of thyroid hormone
to the antithyroid medication actually results in higher remission rates. The rationale
for this may be that by providing an external source for thyroid hormone, higher
doses of antithyroid medications can be given, which may suppress the overactive
immune system in
persons with Graves' disease. This type of therapy remains controversial,
however. When long-term therapy is withdrawn, patients should continue to
be seen by the doctor every three months for the first year, since a relapse of
Graves' disease is most likely in this time period. If a patient does relapse,
antithyroid drug therapy can be restarted, or radioactive iodine or surgery may
be considered.
Radioactive Iodine
Radioactive iodine is given
orally (either by pill or liquid) on a one-time basis to ablate a hyperactive gland. The iodine given for ablative treatment is
different from the iodine used in a scan. (For treatment, the isotope iodine 131
is used, while for a routine scan, iodine 123 is used.) Radioactive iodine is given
after a routine iodine scan, and uptake of the iodine is determined to confirm hyperthyroidism.
The radioactive iodine is picked up by the active cells in the thyroid and
destroys them. Since iodine is only picked up by thyroid cells, the destruction is
local, and there are no widespread side effects with this therapy.
Radioactive iodine
ablation has been safely used for over 50 years, and the only major reasons
for not using it are pregnancy and breast-feeding. This form of
therapy is the treatment of choice for recurring Graves' disease, patients with
severe cardiac involvement, those with multinodular goiter or toxic adenomas,
and patients who cannot tolerate antithyroid drugs. Radioactive iodine must be
used with caution in patients with Graves' related eye disease since recent
studies have shown that the eye disease may worsen after therapy. If a woman
chooses to become pregnant after ablation, it is recommended she wait 8-12
months after treatment before conceiving.
In general, more than 80% of patients are cured with a
single dose of radioactive iodine. It takes between 8 to 12 weeks for the
thyroid to become normal after therapy. Permanent hypothyroidism is the
major complication of
this form of
treatment. While a temporary hypothyroid state may be seen up to six months after treatment with
radioactive iodine, if it persists longer than six months, thyroid replacement therapy
(with T4 or T3) usually is begun.
Surgery
Surgery to partially remove the thyroid gland (partial thyroidectomy)
was once a common form of treatment for hyperthyroidism. The goal is to remove
the thyroid tissue that was producing the excessive thyroid hormone. However, if
too much tissue is removed, an inadequate production of thyroid
hormone (hypothyroidism) may result. In this case, thyroid replacement
therapy is begun. The major complication of surgery is disruption of
the surrounding tissue, including the nerves supplying the vocal cords and the
four tiny glands in the neck that regulate calcium levels in the body (the
parathyroid glands). Accidental removal of these glands may result in low
calcium levels and require calcium replacement therapy.
With the introduction of radioactive iodine therapy and
antithyroid drugs, surgery for hyperthyroidism is not as common as
it used to be. Surgery is appropriate for:
- pregnant patients and children who have
major adverse reactions to antithyroid medications.
- patients
with very large thyroid glands and in those who have symptoms stemming from compression of tissues
adjacent to the thyroid, such as difficulty swallowing,
hoarseness, and shortness of breath.
Next: What's best for you? »
- Beta Blockers - Learn more about Beta Blockers, a drug that treats angina and other heart rhythm disorders, migraines, high blood pressure, panic attacks, and tremors. Generic and brand names are included in the article.
- Thyroid Blood Tests - Read about thyroid blood tests, which are used to diagnose disease of the thyroid such as hyperthyroidism and hyperthyroidism, as well as point to other diseases of the thyroid gland.
- Hypothyroidism - Learn about Hypothyroidism (underactive thyroid) including causes, symptoms (such as weight gain, fatigue, and depression), diagnosis, and treatment.
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