The thyroid is a small, butterfly-shaped gland located in the front of the neck, which produces hormones that control our metabolism, our energy production which operates all our vital processes. These thyroid hormones have a major impact on growth, use of energy, heat production, and infertility, affecting the use of vitamins, proteins, carbohydrates, fats, electrolytes, and water, and regulating the immune response in the intestine. They can also alter the actions of other hormones and drugs.
The main hormone which the thyroid produces is thyroxine (T4). It is made from iodine, which circulates in the blood and 80% is stored in the gland for future use. To be activated it needs to be converted to L-triiodothyronine (T3), so that metabolism can be increased. Only about 20% of T3 is actually formed in the thyroid gland, the rest being manufactured from circulating thyroxine in tissues outside the thyroid. A defect of the production of T4 or conversion to T3 can lead to hypothyroidism, or an underactive thyroid.
The whole process of iodine trapping and thyroid hormone production is directly influenced by another important hormone, thyroid-stimulating hormone (TSH or thyrotropin). This hormone is secreted by the pituitary gland and monitored by thyrotropin-releasing hormone (TRH), which is produced in the hypothalamus gland. Both glands are located in the brain directly behind the eyes. Any abnormality in this intricate system of hormone synthesis and production can have far-reaching consequences to our entire physiology.
How do I know if my thyroid is underactive?
The classic symptoms of a thyroid problem are feeling tired and putting weight on unexpectedly. When there is inadequate secretion of thyroid hormones and our systems begins to slow down. We may develop a soft, diffuse swelling in the region of the throat, which often goes unnoticed. This swelling of the thyroid is termed “goitre”. A number of conditions can cause hypothyroidism, for example inadequate intake of iodine from dietary sources, such as seafood and kelp. About 200 million people around the world have goitres because of insufficient iodine in their diets, although the condition is almost unheard of in developed nations, where iodine has been added to salt.
Ineffective conversion of T4 to T3 or autoimmune thyroid inflammation (Hashimoto’s disease) may also produce hypothyroidism. Occasionally a problem higher up in the pituitary of hypothalamus may lead to lowered TRH and TSH secretion and consequent lowered hormone production by the thyroid.
The most common form of hypothyroidism is Hashimoto’s thyroiditis, a genetic disease named after the Japanese physician who first described thyroid inflammation in 1912. A goitre is always present in these cases, which may appear as a cyst-like or fibrous growth in the neck. Hashimoto’s thyroiditis is thought to be permanent and may require life-long thyroxine treatment.
There are certain drugs which have been reported to cause hypothyroidism:
- Lithium, a drug widely used to treat psychiatric disorders. Up to 50% of patients who take lithium develop goitre
- The drug amiodarone (Cordarone), which is used to treat abnormal heart rhythms contains iodine and can induce hypothyroidism, particularly in patients with an existing thyroid problem.
- Certain antidepressants may cause hypothyroidism, although this effect is infrequent.
- Drugs used for epilepsy, including phenytoin and carbamazepine, reduce thyroid hormone level
- Large doses of selenium, an antioxidant mineral now available over the counter, may also lower thyroid levels.
Hypothyroidism is easily diagnosed by blood tests for T3, T4 and TSH. Antithyroid antibodies indicate the presence of autoimmune thyroiditis and immune therapies may be offered to stop the progression of this disease.
(I have discovered an amazing extract of American ginseng which corrects this problem!) A thyroid ultrasound may be carried out to explore any disease in the gland which may require surgical intervention.
Without treatment hypothyroidism is usually progressive and irreversible, so it ought to be diagnosed and treated as early as possible. There are many natural therapy solutions to treat hypothyroidism: iodine may be taken in the form of kelp – either dietary or supplemental – and l-tyrosine amino acid may be used to help convert T4 to T3. Daily supplementation with thyroxine tablets may be necessary in other cases and it is usually highly successful and allows a patient to live a fully normal life.
I have heard that pregnancy can cause thyroid problems – is this true?
Hypothyroidism develops during or after pregnancy (postpartum) in up to one out of 2,000 women. Often it occurs because women develop antibodies to their own thyroid gland during pregnancy, causing an inflammation of the thyroid to occur after delivery. Some cases are due to thyroid surgery or radiation treatments.
Postpartum autoimmune thyroiditis, occurs in about 5% of women and tends to develop between 4 and 12 months after delivery. It almost always resolves on its own and strangely it may also be interrupted by bouts of thyroid hyperactivity as well. Occasionally, postpartum hypothyroidism can be permanent, particularly in women who have recurrent episodes after multiple pregnancies and in women who have other autoimmune disorders. Women who have diabetes or other autoimmune conditions have a 25% risk for hypothyroidism during pregnancy.
Is it possible to produce too much thyroid hormone and how could this affect me?
Thyroid disorders caused by overproduction of thyroid hormones are called hypothyroidism. Graves disease is the most common form of hyperthyroidism, a condition caused by excessive secretion of thyroid hormones. The cause of the disease is unknown but may be related to a genetic or immune system disorder. It affects 5 out of 10,000 people.
The symptoms of hyperthyroidism may include a goitre, prominent or protruding eyes, weight loss with increased appetite, anxiety, restlessness, intolerance to heat, sweating, fatigue, muscle cramps and weakness, tremor, loose and frequent bowel movements and menstrual irregularities.
Usually a drug called neomercazole is prescribed for these patients to suppress the conversion of T4 to T3. Fortunately these is a western herb called bugleweed which has the same action, a little more subtle and with fewer side effects. Other medical treatments for Graves disease include surgical removal of part or all of the gland or injection of radioactive iodide, which homes in on the thyroid and “nukes” it.
Up to half of patient who receive radioactive iodide — the standard treatment for Graves disease — develop permanent hypothyroidism within a year of therapy and paradoxiacally require thyroxine replacement therapy indefinitely. By the end of five years, about 65% of patients have developed hypothyroidism, after which the rate of hypothyroidism levels off to about 1% a year
The doctor has found a lump on my thyroid gland – could this be serious?
All lumps felt in the neck need to be properly diagnosed by a medical practitioner, yes, for the reason that some may be serious. However the majority of tumours (swellings) which arise from the thyroid are benign, with about only one percent becoming malignant.
Benign nodules of the thyroid are very common, especially in women aged 35-55. They are either composed of glandular tissue or an oily liquid called “colloid” in which thyroxine is usually stored. They often enlarge gradually and require removal due to their size, appearance and compression of neighbouring structures, such as the larynx, causing difficulty swallowing.
Often thyroxine is offered to these patients to shrink their tumours, but rarely is this hormonal treatment effective.
In some instances a thyroid tumour may be hard and immobile, indicating that it may have undergone malignant change. Thyroid cancer can occur in all age groups, and the overall incidence is 1 out of 1,000 people. There is a higher incidence of thyroid cancer is present in people who received radiation therapy as children and in those who have had their neck irradiated. Other risk factors are a family history of thyroid cancer and the long term presence of goitre.
Symptoms which should cause concern:
- enlargement of thyroid gland
- enlarged lymph nodes in the neck
- change of voice or hoarseness
- cough or cough with bleeding
The diagnostic process may involve an ultrasound of the throat, radioactive iodine scan and a tissue biopsy. Hormone assays will also determine the function of the gland.
Treatment varies depending on the type of tumour. A partial or total surgical removal of the thyroid gland with resection of lymph nodes may be necessary. In some cases treatment with radioactive iodine is used and chemotherapy may be given if the tumour is found to have spread beyond the thyroid..
Women under 40 years old have a better chance of a good outcome with treatment of thyroid cancer. The 10-year survival rate (number of people who live at least 10 years after diagnosis) is 46%.
Unfortunately there is no known prevention for thyroid tumours, benign or malignant. Avoidance of radiation to the throat is the only possible preventive strategy we could employ.