This article is intended to simplify the information and thus it does not deal with the less important or rare conditions. It is an overview.
What is the thyroid gland?
The thyroid gland is an “endocrine gland” situated on the front of the neck in the middle. It secretes a hormone called thyroid hormone or thyroxin. This hormone is responsible for controlling the overall metabolic rate of all the cells in the body. Borrowing a metaphor from car engines: it is responsible for the “idling rate” of your body.
What can go wrong with the Thyroid gland?
Broadly I have divided this into two categories:
1. It secretes too much or too little hormone –> function.
2. The gland grows abnormally –> structure.
The two are related and overlap, e.g.: a normal sized gland that over or under functions; an enlarged gland that over or under functions.
They can be evaluated separately.
I have been told that my gland secretes too little hormone?
This condition is called hypothyroidism. It is surprisingly common. It is more common in females than males. It increases in likelihood with increasing age.
What are the symptoms of hypothyroidism?
Because the thyroid hormone is responsible for overall metabolism, it affects the entire body:Some include:
· Dry skin, thin hair or hair loss, fatigue, weakness, lethargy, puffy hands and face, cold intolerance.
· Weight gain.
· Arthritis, stiff joints, backache, muscle cramps or stiffness.
· Menstrual disorders.
· Mental slowness, sleepiness, insomnia, headaches, dizziness.
· Slow heart rate, hypertension, angina.
What is hyperthyroidism and what are the symptoms?
Hyperthyroidism occurs when the thyroid gland secretes too much thyroxin.Symptoms include:
· Palpitations, breathlessness, fast heart rate
· Heat intolerance, nervousness, fatigue, trembling hands, muscle weakness
· Increased bowel movements
· Light or absent menstrual periods
· Weight loss
· Warm moist skin, hair loss
· Staring gaze Many symptoms of hyperthyroidism and hypothyroidism are non specific and so the overall picture has to be taken into account.
What is a thyroid nodule and a goitre?
A thyroid nodule describes a spherical mass inside the gland and the term goitre is used to describe enlargement of the entire gland.
How do we test for thyroid abnormalities?
To test for hormone imbalances (Function), a thyroid function test is done.To test for abnormal enlargements, goitres or nodules (Structure), the following tests need to be done:
· Sonar thyroid to evaluate the anatomy.
· Thyroid radio-nucleotide scan to evaluate the function of the area in question – this can either be defined as:o “hot” which means increased functioning of that nodule/areao “cold” which means decreased functioningo normal
· Biopsy done mainly by fine needle aspiration. Here a thin needle is inserted into the gland and cells are withdrawn for evaluation (not unlike taking blood).
What are the causes of hyperthyroidism?
Graves disease, the commonest cause, occurs when the entire gland is overproducing thyroid hormone.
Less commonly, a single nodule is responsible for the excess hormone secretion, called a “hot” nodule – see above.
Inflammation of the thyroid, described as thyroiditis, can also cause hyperthyroidism.
What are the causes of hypothyroidism?
The commonest cause worldwide is iodine deficiency.Hashimotos thyroiditis caused by the body attacking its own gland (autoimmune).Congenital absent or deficient gland.Deficiency in stimulating hormones from the hypothalamus or pituitary gland.The end result of treatment for hyperthyroidism.Certain medication for mood disorders.
Why is functional thyroid illness (abnormal hormone levels) important?
As the thyroid hormone regulates overall metabolism, imbalances affect the entire body. Thus they increase the risks of several co-morbid conditions especially related to the cardiovascular system. Untreated congenital hypothyroidism can result in severe physical and central nervous system mal-development known as cretinism.
Why is structural thyroid illness (goiter or nodules) important?
Besides a relationship between structure and function;Nodules have an intrinsic risk of cancer.Goiters can result in cosmetic problems, difficulty in swallowing, difficulty in breathing, suspicion of cancer.
How is hypothyroidism treated?
The underlying cause has to be determined and managed accordingly – see above.Thyroid hormone replacement is given for the actual hormone deficiency.
How is hyperthyroidism treated?
The underlying cause is determined and managed.For those that require direct management, the effects of the hormone are blocked using medication.This treatment is effective for as long as it is used. For a more permanent solution, the gland is ablated using radioactive iodine more commonly and surgery less commonly.
How is a nodule managed?
The priority is to exclude a cancer. If this is achieved (using the investigations mentioned above), associated hyperthyroidism is then treated on its own merit, i.e. medical or surgical means.
How is a goiter managed?
The underlying cause, associated hyperthyroidism or hypothyroidism is managed.If cancer is excluded, the goiter can be observed. The only time, surgery will be considered is if the goiter is causing a cosmetic defect, breathing problems or swallowing problems.
How is thyroid cancer treated?
After the extent of spread has been determined, the cancer is managed by a combination of surgery, radioactive iodine, external beam radiotherapy and hormonal manipulation.