Overview
Millions of people around the world have a thyroid disease, such as an enlarged thyroid gland (goiter), non-cancerous or cancerous thyroid nodules, or an overactive thyroid gland. Some thyroid conditions may be treated with medicines, and others may be treated with surgery.
Definition
The thyroid gland is in the lower part of the front of the neck, just in front of the windpipe. It is shaped like a butterfly, with a “lobe” on each side joined by a thin strip of tissue. The nerves that control the vocal cords are just behind the thyroid.
The thyroid gland cannot usually be seen or felt, but if it becomes enlarged, it causes a swelling in the neck called a goiter. Other thyroid conditions may not cause a visible goiter.
The thyroid produces important hormones called thyroxine and T3. These hormones control a person's metabolism — in other words, how the body gets energy from the foods that are eaten. If the thyroid is not working well, the body uses energy more slowly or quickly than it should.
If the thyroid is not active enough, it is called hypothyroidism. Hypothyroidism can make a person gain weight, feel tired, and struggle with cold temperatures. If the thyroid is too active (hyperthyroidism), they will have more thyroid hormones than the body needs. Hyperthyroidism causes people to lose weight, speeds up their heart rate, and makes them very sensitive to heat.
Causes
A goiter can be caused by several conditions. These include:
- Grave's Disease: The thyroid swells and makes too much thyroxine.
- Thyroiditis (Inflammation of the Thyroid): Inflammation can have several causes, such as a viral infection.
- Iodine Deficiency: If there is a lack iodine in the diet, the thyroid swells as it tries to make enough hormones.
- Medication: Some medicines, such as amiodarone, interferon-alpha, and lithium, can cause a goiter.
- Hereditary Factors: Some people inherit a tendency for a large thyroid.
Thyroid nodules (small lumps in the thyroid) may be caused by:
- Cyst: A fluid-filled benign (non-cancerous) tumour
- Adenoma: A solid benign tumour
- Cancerous Tumour: Rare
An overactive thyroid (hyperthyroid) may result from Grave’s disease or thyroid nodules.
The two main causes of an underactive thyroid (hypothyroidism) are autoimmunity (where the thyroid cells are destroyed by white blood cells which attack the thyroid) and as a side-effect of treatment for thyroid disease. Other rare causes include inherited thyroid deficiency, a complication of viral infection, or a side-effect of certain drugs.
Symptoms
If the thyroid is producing too much thyroxine and T3, a person will likely experience some or all of the symptoms of hyperthyroidism (also called thyrotoxicosis):
- Being restless, nervous, emotional, irritable, sleeping poorly, and "always on the go"
- Shaking hands
- Losing weight despite increased appetite
- Palpitations
- Sweating, a dislike of heat and an increased thirst
- Diarrhea or needing to go to the toilet more often than normal
- Shortness of breath
- Skin problems such as hair thinning and itching
- Menstrual changes, periods becoming very light or infrequent
- Tiredness and muscle weakness
- A swelling of the thyroid gland in the neck (goiter)
Risk Factors
There are some factors that can increase the risk of developing a thyroid disease. Some of these are:
- Gender: Women are 6 to 8 times more likely than men to develop a thyroid condition.
- Age: People aged over 50 years have increased risk of thyroid disease.
- Family or Personal History: For example, if there were thyroid problems during or after pregnancy, or if people in a person's close family have had thyroid conditions, their risk of thyroid disease is increased.
- Cigarette Smoking: If a person is or was a smoker, they have an increased risk of developing autoimmune thyroid disease.
- Iodine intake: If a person does not have enough iodine in their diet or, conversely, if they use iodine or herbal supplements, they may increase the risk of thyroid problems.
- Medication: Certain medical treatments and drugs increase the risk of developing thyroid problems.
- Major Stress: Significant life events like death or divorce, or major physical stress like a car accident, may trigger autoimmune thyroid disease.
Diagnosis
To diagnose a thyroid problem, a doctor will need to examine the patient. A doctor will pay special attention to the thyroid gland and other areas of the body where thyroid problems may be reflected, such as the skin, nails, hair, heart, weight, and body temperature. In addition, blood tests will be performed to measure the levels of thyroid hormones. They may also need to have thyroid imaging tests so the doctor can “see” the thyroid. Lastly, if there is a lump on the thyroid, a thin needle may be inserted directly into the lump to remove some cells that will be checked for cancer.