What is hyperthyroidism?
Hyperthyroidism is a condition of the thyroid. The
thyroid is a small, butterfly-shaped gland located at the front of your neck.
It produces tetraiodothyronine (T4) and triiodothyronine (T3), which are two
primary hormones that control how your cells use energy. Your thyroid gland
regulates your metabolism through the release of these hormones.
Hyperthyroidism occurs when the thyroid makes too
much T4, T3, or both. Diagnosis of overactive thyroid and treatment of the
underlying cause can relieve symptoms and prevent complications.
What causes hyperthyroidism?
A variety of conditions can cause hyperthyroidism.
Graves' disease, an autoimmune disorder, is the most common cause of
hyperthyroidism. It causes antibodies to stimulate the thyroid to secrete too
much hormone. Graves’ disease occurs more often in women than in men. It tends
to run in families, which suggests a genetic link. You should tell your doctor
if your relatives have had the condition.
Other causes of hyperthyroidism include:
- excess iodine, a key ingredient in T4 and T3
- thyroiditis, or inflammation of the thyroid,
which causes T4 and T3 to leak out of the gland
- tumors of the ovaries or testes
- benign tumors of the thyroid or pituitary gland
- large amounts of tetraiodothyronine taken
through dietary supplements or medication
What are the
symptoms of hyperthyroidism?
High amounts of T4, T3, or both can cause an
excessively high metabolic rate. This is called a hypermetabolic state. When in
a hypermetabolic state, you may experience a rapid heart rate, elevated blood
pressure, and hand tremors. You may also sweat a lot and develop a low
tolerance for heat. Hyperthyroidism can cause more frequent bowel movements,
weight loss, and, in women, irregular menstrual cycles.
Visibly, the thyroid gland itself can swell into a
goiter, which can be either symmetrical or one-sided. Your eyes may also appear
quite prominent, which is a sign of exophthalmos, a condition that’s related to
Other symptoms of hyperthyroidism include:
- increased appetite
- inability to concentrate
- irregular heartbeat
- difficulty sleeping
- fine, brittle hair
- hair loss
- nausea and vomiting
- breast development in men
The following symptoms require immediate medical
- shortness of breath
- loss of consciousness
- fast, irregular heart rate
Hyperthyroidism can also cause atrial fibrillation,
a dangerous arrhythmia that can lead to strokes, as well as congestive heart
How do doctors
Your first step in diagnosis is to get a complete medical
history and physical exam. This can reveal these common signs of
- weight loss
- rapid pulse
- elevated blood pressure
- protruding eyes
- enlarged thyroid gland
Other tests may be performed to further evaluate
your diagnosis. These include:
Your doctor may need to check your cholesterol
levels. Low cholesterol can be a sign of an elevated metabolic rate, in which
your body is burning through cholesterol quickly.
T4, free T4, T3
These tests measure how much thyroid hormone (T4
and T3) is in your blood.
Thyroid stimulating hormone level test
Thyroid stimulating hormone (TSH) is a pituitary
gland hormone that stimulates the thyroid gland to produce hormones. When
thyroid hormone levels are normal or high, your TSH should be lower. An
abnormally low TSH can be the first sign of hyperthyroidism.
Your triglyceride level may also be tested.
Similar to low cholesterol, low triglycerides can be a sign of an elevated
scan and uptake
This allows your doctor to see if your thyroid is
overactive. In particular, it can reveal whether the entire thyroid or just a
single area of the gland is causing the overactivity.
Ultrasounds can measure the size of the entire
thyroid gland, as well as any masses within it. Doctors can also use ultrasounds
to determine if a mass is solid or cystic.
or MRI scans
A CT or MRI can show if a pituitary tumor is
present that’s causing the condition.
How to treat hyperthyroidism
Antithyroid medications, such as methimazole
(Tapazole), stop the thyroid from making hormones. They are a common treatment.
Radioactive iodine is given to over 70 percent
of U.S. adults with hyperthyroidism, according to the American Thyroid
Association. It effectively destroys the cells that produce hormones.
Common side effects include dry mouth, dry eyes,
sore throat, and changes in taste. Precautions may need to be taken for a short
time after treatment to prevent radiation spread to others.
A section or all of your thyroid gland may be
surgically removed. You will then have to take thyroid hormone supplements to
prevent hypothyroidism, which occurs when you have an underactive thyroid that
secretes too little hormone. Also, beta-blockers such as propranolol can
help control your rapid pulse, sweating, anxiety, and high blood pressure. Most
people respond well to this treatment.
What you can do to
Eating a proper diet, with a focus on calcium and
sodium, is important, especially in preventing hyperthyroidism. Work with your
doctor to create healthy guidelines for your diet, nutritional supplements, and
Hyperthyroidism can also cause your bones to
become weak and thin, which can lead to osteoporosis. Taking vitamin D and
calcium supplements during and after treatment can help strengthen your bones.
Your doctor can tell you how much vitamin D and calcium to take each day.
Your doctor may refer you to an endocrinologist,
who specializes in treating bodily hormone systems. Stress or infections can
cause thyroid storm. Thyroid storm happens when a large amount of thyroid
hormone is released and it results in a sudden worsening of symptoms. Treatment
is important to prevent thyroid storm, thyrotoxicosis, and other complications.
The long-term outlook for hyperthyroidism depends
on its cause. Some causes can go away without treatment. Others, like Graves'
disease, get worse over time without treatment. The complications of Graves'
disease can be life-threatening and affect your long-term quality of life.
Early diagnosis and treatment of symptoms improve the long-term outlook.