What is Hypothyroidism?
The thyroid, a butterfly-shaped gland at the base of the neck, is responsible for producing the hormones that regulate metabolism. The two main hormones produced by the thyroid are thyroxine (T4) and triiodothyronine (T3). These hormones maintain the rate at which the body uses carbohydrates and fats; they are also involved in the regulation of heart rate and body temperature. Calcitonin, another important thyroid hormone, is needed to maintain the proper amount of calcium in the blood.
Hypothyroidism, or underactive thyroid, occurs when the thyroid does not produce enough of these hormones. Abnormally low levels of thyroid hormone can cause an imbalance in the chemical reactions that control many functions of the body, leading to widespread consequences for overall health.
While anyone can experience hypothyroidism, there are some risk factors involved. Women over fifty are more likely to develop the disorder. People who have close family members with an autoimmune disease are at an increased risk, as are those who have received radiation to the neck and chest or had thyroid surgery.
Causes of Hypothyroidism
- One of the leading causes of hypothyroidism, particularly in the United States, is an autoimmune disorder known as Hashimoto's thyroiditis. This condition causes the immune system to produce antibodies which attack thyroid tissue, eventually impairing the body's ability to produce thyroid hormone.
- Worldwide, the number one cause of hypothyroidism is the deficiency of iodine. Found mainly in seafood and seaweed, iodine is a mineral needed for the production of thyroid hormone. While the problem of iodine deficiency has been virtually eliminated in Western countries by adding the mineral to table salt, insufficient dietary iodine continues to be the main cause of hypothyroidism in developing countries.
- Certain treatments for hyperthyroidism (the overproduction of thyroid hormone) are also known to cause hypothyroidism. Hyperthyroidism is often treated with radioactive iodine or other anti-thyroid medications which may impair the ability of the thyroid to produce hormones. Some patients who develop hypothyroidism may require lifelong treatment as a result.
- Thyroid surgery, in which a part of the thyroid gland is removed, may be employed to treat conditions such as hyperthyroidism and certain cancers. Removal of part of the thyroid gland may result in the underproduction of thyroid hormone.
- Radiation treatment of the head and neck areas, used in combatting certain types of cancer, can destroy the thyroid gland and cause hypothyroidism.
- Congenital hypothyroidism occurs in about 1 out of every 3,000 newborns in the U.S. Infants born with a smaller-than-normal thyroid gland are at risk for developmental difficulties, including severe mental and physical retardation. Fortunately, the condition is easily detectable, and babies who receive treatment within the first few months after birth have an excellent chance of developing normally.
Some less common causes of hypothyroidism are also known:
> Certain viral and bacterial infections may cause short-term hypothyroidism;
> Medications such as lithium carbonate and interferon alpha, can interfere with thyroid function;
> Rarely, hypothyroidism may appear as the result of an abnormality in the hypothalamus or pituitary gland;
> During or shortly after pregnancy, some women may develop hypothyroidism, which can cause complications for both the mother and the developing fetus.
Symptoms of Hypothyroidism
Hypothyroidism can be difficult to recognize in its beginning stages. It progresses slowly, and it may take years before any clear symptoms become evident. Early symptoms such as weakness and fatigue can easily be attributed to other causes.
The signs and symptoms of hypothyroidism are widely variable, and their severity depends on the degree of hormone deficiency. As the metabolism slows, symptoms become more obvious and may include:
- Chronic fatigue
- Muscle weakness
- Unexplained weight gain
- Increased sensitivity to cold
- Puffiness of the face
- Increased paleness and dry skin
- Hoarse or raspy voice
- Heavier than normal menstruation
- Brittle hair and nails
- Joint and muscle aches and pains
If left untreated, the symptoms of hypothyroidism may increase in severity. Possible complications of the disease include goiter (enlargement of the thyroid gland, which can cause difficulties with breathing and swallowing), heart problems, and mental health issues such as depression. In exceptional cases, decreased mental function may occur.
In extreme cases, advanced hypothyroidism can lead to myxedema, a rare and life-threatening condition characterized by low blood pressure, decreased breathing and body temperature, lack of responsiveness and coma.
Testing for Hypothyroidism
Testing for hypothyroidism is done by a thyroid blood test. It is routine, and some doctors recommend regular screening for people at risk for the disorder. All states in the U.S. now require hospitals to do a thyroid blood test for newborns, as early detection and treatment in infants is critical to their long-term physical and mental development.
Diagnosing low levels of thyroid hormone is a straightforward process. If you or your doctor suspect that you may be suffering from an underactive thyroid, a combination of thyroid blood tests are used to confirm the diagnosis.
- The thyroid-stimulating hormone (TSH) assay is a test used to detect TSH levels in the blood. TSH is a hormone produced by the pituitary gland which regulates the amount of hormones the thyroid gland
- Thyroxine measurement is a hypothyroidism test which detects the amount of thyroxine (T4) in the blood.
High levels of TSH combined with a low level of thyroxine indicates that the thyroid is underactive. TSH testing is highly accurate, and it can be used to detect low levels of thyroid hormone before symptoms become apparent. If test results are abnormal, further testing is occasionally necessary if the cause of the hypothyroidism is unclear.
An antithyroid antibody test may be used to determine whether you have Hashimoto's thyroiditis. In s small number of cases, a CT scan or MRI test may be used to view any abnormalities in the pituitary gland or hypothalamus.
The standard hypothyroid treatment consists of prescribing the synthetic thyroid hormone levothyroxine. Levothyroxine is highly effective, and most people experience no side effects. While periodic blood tests may be needed to determine the correct dosage of levothyroxine, and some patients may require lifetime hypothyroidism treatment and monitoring, thyroid function normalizes quickly once the hormone therapy has begun.
Signs of weakness and fatigue generally begin to dissipate within a week or two; other symptoms will gradually disappear as well once chemical imbalances resulting from underactive thyroid return to normal.
As an alternative to synthetic thyroxine, extracts from the thyroid glands of pigs are also available by prescription.
Thyroid Natural Remedies
For mild or subclinical hypothyroidism some people can be controlled thyroid natural remedies such as glandular thyroid supplements or thyroid supplements that nourish and strengthen the thyroid gland. Getting sufficient amounts of iodine is also important for normal thyroid levels.
Thyroid levels should be rechecked in 6 weeks to confirm that whichever thyroid treatment method you chose was effective in restoring normal thyroid levels.