What is Hyperthyroidism (Overactive Thyroid)?
The thyroid gland is a small butterfly shaped gland that is located in
the lower front of the neck just under the Adam's apple. The thyroid gland
produces hormones that control the body's organ functions and metabolism.
Hyperthyroidism is an overfunctioning of the thyroid gland which
results in the production of excessive thyroid hormones. This speeds up
most of the chemical reactions in the body and causes mental and physical
changes. An excess of thyroid hormones causes a toxic condition called thyrotoxicosis.
Approximately 2 % of American adults suffer from hyperthyroidism. It is more
prevalent in women than in men, by a ratio of about 8 to 1 and
is most common in young to middle-aged women. Overactive thyroid gland is
potentially dangerous thyroid condition and, if left untreated, can cause
potentially fatal heart rhythm abnormalities and osteoporosis.
Hyperthyroidism causes
Hyperthyroidism is usually due to an 'autoimmune' condition. An autoimmune disease occurs when the body's immune system becomes
misdirected and attacks the very organs, cells, or tissues that it was designed
to protect.
For some reason the body suddenly recognises the thyroid gland as foreign,
and starts to attack it. The reason for this is unclear. However, instead
of destroying the gland this attack actually stimulates it.
The thyroid gland starts to overwork and produce excess thyroid hormone.
Hyperthyroidism can be caused by:
- Graves' disease, named after, Robert Graves,
the physician who first described this form of hyperthyroidism. Graves'
disease is the most common cause of hyperthyroidism, accounting for 60
to 80 percent of all cases. It is an autoimmune disease caused by an antibody,
active against the thyroid-stimulating hormone (TSH) receptor, which stimulates
the gland to synthesize and secrete excess thyroid hormone.
- Toxic nodules or goiters on the thyroid. Toxic multinodular goiter
causes 5% of the cases of hyperthyroidism in the United States and can
be 10 times more common in iodine-deficient areas. It typically occurs
in patients older than 40 years with a long-standing goiter, and has a
more insidious onset than Graves' disease.
- Excessive thyroid medication (treatment induced hyperthyriodism)
- Iodine-induced hyperthyroidism can occur after intake
of excess iodine in the diet, exposure to radiographic contrast media,
or medications. Excess iodine increases the synthesis and release
of thyroid hormone in iodine-deficient patients and in older patients
with preexisting multinodular goiters.
- Amiodarone-induced hyperthyroidism can be found
in up to 12% of patients, especially those in iodine-deficient areas.
Amiodarone contains 37% iodine and is the most common source of iodine
excess in the United States. Medications such as interferon and interleukin-2
(aldesleukin) also can cause hyperthyroidism.
- Thyroid hormone-induced is caused by the intentional
or accidental ingestion of excess amounts of thyroid hormone. Some
patients may take thyroid preparations to achieve weight loss.
- Thyroiditis (an inflammation of the thyroid)
- Subacute thyroiditis produces an abrupt onset of thyrotoxic
symptoms as hormone leaks from an inflamed gland. It often follows
a viral illness. Symptoms usually resolve within eight months. This
condition can be recurrent in some patients.
- Lymphocytic thyroiditis and postpartum (subacute
lymphocytic) thyroiditis are transient inflammatory causes of hyperthyroidism
that, in the acute stage, may be clinically indistinguishable from
Graves' disease. Postpartum thyroiditis can occur in up to 5 to 10%
of women in the first three to six months after delivery. A transient
hypothyroidism often occurs before resolution.
Hyperthyroidism risk factors
- Pregnancy - 5 to 8% of women develop postpartum inflammation of the thyroid
- Age 20 to 50 years
- Women are more likely than men to develop hyperthyroidism
- Family history of Graves' disease or other forms of hyperthyroidism increases your risk
- Japanese ancestry appear to be at greater risk of hyperthyroidism
- Previous treated/untreated problems (nodules, hyperthyroidism, goiter, hypothyroidism)
- Another autoimmune disease
Hyperthyroidism symptoms
All the symptoms can be caused by other problems, and so the diagnosis
may not be obvious at first. Usually the symptoms of hyperthyroidism are
so gradual in their onset that people don't realize the symptoms until they
become more severe. This means the symptoms may continue for weeks or months
before people fully realize that they are sick. In older people, some or
all of the typical symptoms of hyperthyroidism may be absent, and the person
may just lose weight or become depressed.
The symptoms usually are related to an increase in the metabolic rate
of the body. Common symptoms include:
- Enlarged thyroid gland
- Rapid heart beat (tachycardia) or heart palpitations
- Trouble sleeping
- Nervousness, irritability
- Restlessness
- Feeling anxiety
- Depression
- Fatigue
- Tremor of the fingertips
- Skin changes (smooth, velvety skin)
- Weight loss
- Fine brittle hair
- Increased appetite
- Increased bowel movements, diarrhea
- Changes in sex drive
- Muscle weakness, especially in the upper arms and thighs
- Heat intolerance
- Increased sweating
- For women, irregular menstrual cycle and reduced menstrual flow
Treatment of overactive thyroid
The main aim of treatment is to reduce the level of thyroxine to normal.
Anti-Thyroid Drugs
For patients with sustained forms of hyperthyroidism, such as Graves' disease
or toxic nodular goiter, antithyroid medications are often used. These drugs
act directly on the thyroid gland to block the production of thyroid hormones.
Two common drugs in this category are methimazole and propylthiouracil (PTU).
When taken rightly, they are usually very effective in controlling
hyperthyroidism within a few weeks. The main shortcoming is that the underlying hyperthyroidism often comes
back after they are discontinued especially in patients over the age of
45 years, also in those with a large goitre and in those with severe hyperthyroidism.
For this reason, many patients with hyperthyroidism are advised to consider
a treatment that permanently prevents the thyroid gland from producing too much thyroid hormone.
Radioactive Iodine
Radioactive iodine (RAI) is the most widely recommended permanent treatment
of hyperthyroidism. This treatment has been used since 1940, and no serious
complications from RAI have become apparent to the date. Radioactive
iodine takes advantage of the fact that thyroid cells are the
only cells in the body which have the ability to absorb iodine. When thyroid
cells absorb radioactive iodine they will be damaged or killed. Because
iodine is not concentrated by any other cells in the body, there is very
little radiation exposure for the rest of the body. This form of therapy
often takes one to two months before the thyroid has been killed, but the
radioactivity medicine is completely gone from the body within a few days.
The main problem is, that because the damage to the thyroid cannot be
controlled, the thyroid of most patients becomes underactive (hypothyroidism)
after RAI. This condition is then treated with a thyroid hormone supplement.
This may seem silly - trading one thyroid problem for another. But hyperthyroidism
is much more dangerous, and difficult to control, than is hypothyroidism.
So while becoming hypothyroid may not be a perfect outcome, it is much better
than being hyperthyroid.
Surgical Removal of the Gland or Nodule
Another permanent cure for hyperthyroidism is to surgically remove all
or part of the thyroid gland. This surgery is known as a thyroidectomy.
Surgery is not used as frequently as the other options.
The biggest reason for this is that the most common forms of hyperthyroidism
are a result of overproduction from the entire gland and the methods described
above work quite well in the vast majority of cases. A potential downside
of the surgical approach is that there is a small risk of injury to structures
near the thyroid gland in the neck. The incidence of this is about 1%. Like
radioactive iodine treatment, surgery often results in hypothyroidism. Therefore,
anyone who has been hyperthyroid and been treated by one of the above methods
should have a blood test at least once a year to measure thyroid function.
Supplements helpful for Hyperthyroidism
Natural treatments can often reduce or eliminate the need for drugs and
surgery. Since metabolism is dramatically increased in this condition, nutrients
are used up more quickly than normal. For this reason, multivitamins provide
the necessary replacements. In addition, add vitamins C and B complex for
extra support from the stress of such overactivity. The essential fatty
acids often help treat autoimmune reactions. They provide building blocks
for prostaglandins, which prevent inflammation in the body. Other important
nutrients for thyroid health are zinc, copper, selenium, iodine, grape seed
extract, coenzyme Q10 and the amino acid, tyrosine.
- Calcium
Reduced bone mass has been identified as a common problem in cases of
hyperthyroidism. Research indicates that early detection of the problem
and treatment with a calcium supplement helps to reduce the risk of osteoporosis.
- Melatonin
Melatonin is a substance secreted by the pineal gland in the brain. It
plays a role in sleep patterns and the circadian rhythms of the body.
Melatonin is also a potent antioxidant and an effective free radical scavenger
in hyperthyroidism. It has been shown to suppress thyroxine production. Supplementation with melatonin is also beneficial
for insomnia, which is a common symptom of hyperthyroidism.
- L-carnitine
Nutritional supplementation with L-carnitine has been shown to have a
beneficial effect on the symptoms of hyperthyroidism, and L-carnitine
may help prevent bone demineralization caused by the disease. Carnitine
is an amino acid that plays a pivotal role in the production of energy
inside the cell. It is thought to affect thyroid hormone by blocking
its action in cells. Carnitine also had beneficial effects on bone metabolism.
- Niacin
Niacin (Vitamin B3, nicotinic acid) was shown in a clinical trial to decrease
the concentration of serum thyroid hormones in individuals who were euthyroid.
Because no adverse effects of supplementation were observed, niacin may
be an adjunctive therapy for hyperthyroidism. It may be wise to use niacinamide,
another form of niacin, because it does not cause flushing.
- Vitamin A
Vitamin A and beta-carotene levels in the blood of patients with hyperthyroidism
are often decreased and supplementing with large amounts of this particular
vitamin actually inhibits thyroid function. The supplementation of Vitamin
A also ameliorates the symptoms of Grave's disease. Vitamin A is a potent
antioxidant, which thwarts the oxidative stress that is increased in those
with hyperthyroidism.
- Vitamin C
Vitamin C is a potent anti-oxidant. It has been shown in experimental
studies to be decreased in individuals with excess thyroid hormone activity.
- Vitamin E
Vitamin E is an anti-oxidant. It also functions to stabilize cell membranes.
It can act as a free radical quencher and decrease the damage caused by
oxidative stressors in hyperthyroid patients.
- Digestive enzymes
Digestive enzymes may be beneficial in cases of overactive thyroid. The
ability of the body to adequately digest and absorb nutrients from the
diet may be reduced in people with hyperthyroidism.
Herbal remedies helpful for overactive thyroid
Lycopus ssp, Lithospermum officinale, and Melissa officinalis have all
been proven to treat hyperthyroidism. The mechanism of action in these herbs,
is the blocking of TSH receptors on the thyroid cells. These three herbs
have had repeated success in treating Grave's disease as well, because of
interruption of the Grave's specific thyroid stimulating immunoglobulin. In fact, one study found that freeze dried extracts
of the three herbs inhibited binding of TSH to thyroid receptors by weakly
binding themselves.
Herbs and supplements to avoid
According to one study in animals, the herb ashwaghanda may raise thyroid
hormone levels. For this reason, it should not be used by people with overactive
thyroid. Taking excessive kelp, bladderwrack, or other forms of seaweed
can cause hyperthyroidism by overloading the body with iodine.
