Goiter
Overview
A goiter (GOI-tur) is the irregular growth of
the thyroid gland. The thyroid is a butterfly-shaped gland located at the base
of the neck just below the Adam's apple.
A goiter may be an overall enlargement of the
thyroid, or it may be the result of irregular cell growth that forms one or
more lumps (nodules) in the thyroid. A goiter may be associated with no change
in thyroid function or with an increase or decrease in thyroid hormones.
The most common cause of goiters worldwide is
a lack of iodine in the diet. In the United States, where the use of iodized
salt is common, goiters are caused by conditions that change thyroid function
or factors that affect thyroid growth.
Treatment depends on the cause of the goiter,
symptoms, and complications resulting from the goiter. Small goiters that
aren't noticeable and don't cause problems usually don't need treatment.
Symptoms
Most people with goiters have no signs or
symptoms other than a swelling at the base of the neck. In many cases, the
goiter is small enough that it's only discovered during a routine medical exam
or an imaging test for another condition.
Other signs or symptoms depend on whether
thyroid function changes, how quickly the goiter grows and whether it obstructs
breathing.
Underactive thyroid
(hypothyroidism)
Signs and symptoms of hypothyroidism include:
·
Fatigue
·
Increased sensitivity
to cold
·
Increased sleepiness
·
Dry skin
·
Constipation
·
Muscle weakness
·
Problems with memory
or concentration
Overactive thyroid
(hyperthyroidism)
Signs and symptoms of hyperthyroidism include:
·
Weight loss
·
Rapid heartbeat
(tachycardia)
·
Increased sensitivity
to heat
·
Excess sweating
·
Tremors
·
Irritability and
nervousness
·
Muscle weakness
·
Frequent bowel
movements
·
Changes in menstrual
patterns
·
Sleep difficulty
·
High blood pressure
·
Increased appetite
Children with hyperthyroidism might also have
the following:
·
Rapid growth in height
·
Changes in behavior
·
Bone growth that
outpaces expected growth for the child's age
Obstructive goiter
The size or position of a goiter may obstruct
the airway and voice box. Signs and symptoms may include:
·
Difficulty swallowing
·
Difficulty breathing
with exertion
·
Cough
·
Hoarseness
·
Snoring
Causes
How the thyroid gland
works
Two hormones produced by the thyroid are
thyroxine (T-4) and triiodothyronine (T-3). When the thyroid
releases T-4 and T-3 into the bloodstream, they play a role
in many functions in the body, including the regulation of:
·
The conversion of food
into energy (metabolism)
·
Body temperature
·
Heart rate
·
Blood pressure
·
Other hormone
interactions
·
Growth during
childhood
The thyroid gland also produces calcitonin, a
hormone that helps regulate the amount of calcium in the blood.
How the thyroid is
regulated
The pituitary gland and hypothalamus control
the rate at which T-4 and T-3 are produced and released.
The hypothalamus is a specialized region at
the base of the brain. It acts as a thermostat for maintaining balance in
multiple body systems. The hypothalamus signals the pituitary gland to make a
hormone known as thyroid-stimulating hormone (TSH).
The pituitary gland — located below the
hypothalamus — releases a certain amount of TSH, depending on how
much T-4 and T-3 are in the blood. The thyroid gland, in
turn, regulates its production of hormones based on the amount of TSH it
receives from the pituitary gland.
Causes of goiter
A number of factors that influence thyroid
function or growth can result in a goiter.
·
Iodine
deficiency. Iodine is
essential for the production of thyroid hormones. If a person does not get
enough dietary iodine, hormone production drops and the pituitary gland signals
the thyroid to make more. This increased signal results in thyroid growth. In
the United States, this cause is uncommon because of iodine added to table
salt.
·
Hashimoto's
disease. Hashimoto's
disease is an autoimmune disorder, an illness caused by the immune system
attacking healthy tissues. The damaged and inflamed tissues of the thyroid
don't produce enough hormones (hypothyroidism). When the pituitary gland
detects the decline and prompts the thyroid to create more hormones, the
thyroid can become enlarged.
·
Graves'
disease. Another
autoimmune disorder called Graves' disease occurs when the immune system
produces a protein that mimics TSH. This rogue protein prompts the thyroid
to overproduce hormones (hyperthyroidism) and can result in thyroid growth.
·
Thyroid
nodules. A nodule is the
irregular growth of thyroid cells that form a lump. A person may have one
nodule or several nodules (multinodular goiter). The cause of nodules is not clear,
but there may be multiple factors — genetics, diet, lifestyle and environment.
Most thyroid nodules are noncancerous (benign).
·
Thyroid
cancer. Thyroid cancer
is less common than other cancers and generally treatable. About 5% of people
with thyroid nodules are found to have cancer.
·
Pregnancy. A hormone produced during pregnancy,
human chorionic gonadotropin (HCG), may cause the thyroid gland to be
overactive and enlarge slightly.
·
Inflammation. Thyroiditis is inflammation of the
thyroid caused by an autoimmune disorder, bacterial or viral infection, or
medication. The inflammation may cause hyperthyroidism or hypothyroidism.
Risk factors
Anyone can develop a goiter. It may be present
at birth or occur at any time throughout life. Some common risk factors for
goiters include:
·
A
lack of dietary iodine. Iodine
is found primarily in seawater and in the soil in coastal areas. In the
developing world in particular, people who don't have enough iodine in their
diets or access to food supplemented with iodine are at increased risk. This is
rare in the United States.
·
Being
female. Women are more
likely to develop a goiter or other thyroid disorders.
·
Pregnancy
and menopause. Thyroid problems
in women are more likely to occur during pregnancy and menopause.
·
Age. Goiters are more common after age 40.
·
Family
medical history. Family medical
history of goiters or other thyroid disorders increases the risk of goiters.
Also, researchers have identified genetic factors that may be associated with
an increased risk.
·
Medications. Some medical treatments, including the
heart drug amiodarone (Pacerone) and the psychiatric drug lithium (Lithobid),
increase your risk.
·
Radiation
exposure. Your risk
increases if you've had radiation treatments to your neck or chest area.
Complications
A goiter itself usually doesn't cause
complications. The appearance may be troublesome or embarrassing for some
people. A large goiter may obstruct the airway and voice box.
Changes in the production of thyroid hormones
that may be associated with goiters have the potential for causing
complications in multiple body systems.
Diagnosis
A goiter is often discovered during a routine
physical exam. By touching your neck, your health care provider may detect an
enlargement of the thyroid, an individual nodule or multiple nodules. Sometimes
a goiter is found when you are undergoing an imaging test for another
condition.
Additional tests are then ordered to do the
following:
·
Measure the size of
the thyroid
·
Detect any nodules
·
Assess whether the
thyroid may be overactive or underactive
·
Determine the cause of
the goiter
Tests may include:
·
Thyroid
function tests. A blood sample
can be used to measure the amount of TSH produced by the pituitary
gland and how much T-4 and T-3 is produced by the thyroid.
These tests can show whether the goiter is associated with an increase or
decrease in thyroid function.
·
Antibody
test. Depending on the
results of the thyroid function test, your health care provider may order a
blood test to detect an antibody linked to an autoimmune disorder, such as
Hashimoto's disease or Graves' disease.
·
Ultrasonography. Ultrasonography uses sound waves to
create a computerized image of tissues in your neck. The technician uses a
wand-like device (transducer) over your neck to do the test. This imaging
technique can reveal the size of your thyroid gland and detect nodules.
·
Radioactive
iodine uptake. If your health
care provider orders this test, you are given a small amount of radioactive
iodine. Using a special scanning device, a technician can measure the amount
and rate at which your thyroid takes it in. This test may be combined with a
radioactive iodine scan to show a visual image of the uptake pattern. The
results may help determine function and cause of the goiter.
·
Biopsy. During a fine-needle aspiration biopsy,
ultrasound is used to guide a very small needle into your thyroid to obtain a
tissue or fluid sample from nodules. The samples are tested for the presence of
cancerous cells.
Treatment
Goiter treatment depends on the size of the
goiter, your signs and symptoms, and the underlying cause. If your goiter is
small and your thyroid function is healthy, your health care provider may
suggest a wait-and-see approach with regular checkups.
Medications
Medications for goiters may include one of the
following:
·
For
increasing hormone production. An underactive thyroid is treated with a thyroid hormone
replacement. The drug levothyroxine (Levoxyl, Thyquidity, others)
replaces T-4 and results in the pituitary gland releasing
less TSH. The drug liothyronine (Cytomel) may be prescribed as
a T-3 replacement. These treatments may decrease the size of the
goiter.
·
For
reducing hormone production. An overactive thyroid may be treated with an anti-thyroid
drug that disrupts hormone production. The most commonly used drug, methimazole
(Tapazole), may also reduce the size of the goiter.
·
For
blocking hormone activities. Your health care provider may prescribe a drug called a
beta blocker for managing symptoms of hyperthyroidism. These drugs — including
atenolol (Tenormin), metoprolol (Lopressor) and others — can disrupt the excess
thyroid hormones and lower symptoms.
·
For
managing pain. If inflammation
of the thyroid results in pain, it's usually treated with aspirin, naproxen
sodium (Aleve), ibuprofen (Advil, Motrin IB, others) or related pain relievers.
Severe pain may be treated with a steroid.
Surgery
You may need surgery to remove all or part of
your thyroid gland (total or partial thyroidectomy) may be used to treat goiter
with the following complications:
·
Difficulty breathing
or swallowing
·
Thyroid nodules that
cause hyperthyroidism
·
Thyroid cancer
You may need to take thyroid hormone
replacement, depending on the amount of thyroid removed.
Radioactive iodine
treatment
Radioactive iodine is a treatment for an
overactive thyroid gland. The dose of radioactive iodine is taken orally. The
thyroid takes up the radioactive iodine, which destroys cells in the thyroid.
The treatment lowers or eliminates hormone production and may decrease the size
of the goiter.
As with surgery, you may need to take thyroid
hormone replacement to maintain the appropriate levels of hormones.
Lifestyle and home
remedies
Your body gets iodine from your food. The
recommended daily allowance is 150 micrograms. A teaspoon of iodized salt has
about 250 micrograms of iodine.
Foods that contain iodine include:
·
Saltwater fish and
shellfish
·
Seaweed
·
Dairy products
·
Soy products
Most people in the United States get enough
iodine in a healthy diet. Too much iodine in the diet, however, can cause thyroid
dysfunction.
Preparing for your
appointment
If you've been diagnosed with a goiter, you're
likely to have further tests to determine the cause. You might find it helpful
to make a list of questions to ask your health care provider, such as:
·
What caused this
goiter to develop?
·
Is it serious?
·
What can be done to
treat the underlying cause?
·
I have other health
conditions. How can I best manage them together?
·
What are the
alternatives to the main treatment that you're proposing?
·
What will happen if I
choose to do nothing?
·
Will the goiter
continue to get larger?
·
How often should I
have follow-up appointments?
·
Will the treatment
you're suggesting improve the appearance of the goiter?
·
Will I have to take
medication? For how long?
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