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Thyroid basics
What is the thyroid gland?
The thyroid gland is a soft, small, bow-shaped gland, which is located in the neck, below the voice box, or larynx.
Thyroid function
The thyroid gland is part of the endocrine system and produces the hormones thyroxine (T4) and triiodothyronine (T3), which regulate the rate of metabolism. The thyroid gland is controlled by the hypothalamus and pituitary glands at the base of the brain.
TSH (thyroid stimulating hormone), which is secreted by the pituitary gland, travels through the blood to stimulate the production of thyroxine from your thyroid gland.
T4 controls your metabolism. If there is not enough T4, your body will slow and become hypothyroid. If you have too much T4, your body will speed up and become hyperthyroid
As T4 has an influence over every cell in your body, you will notice changes.
T4 also controls growth of the brain in the foetus and linear growth (height) in children.
What causes thyroid disease?
There are many possible causes of thyroid disease. These include:
- iodine deficiency
- autoimmune disease
- an imbalance in T4 production
- nodules which have formed on the gland
- benign and malignant (cancer) tumours of the thyroid
Is thyroid disease common?
One in 7 Australians will be diagnosed with some form of thyroid disease and women are five times more likely than men to develop a thyroid condition. Thyroid disease, especially hypothyroidism – or an underactive thyroid – becomes more common as we grow older.
Iodine deficiency has re-emerged in Australia and we can expect more people to suffer from swelling and enlargement of the thyroid gland, also known as ‘goitre’.
Diagnosing thyroid disease
Thyroid disease can be difficult to diagnose, due to many symptoms being similar to those of other conditions. Your doctor may:
- palpate, or feel, your neck for any sign of swelling
- check your heart rate and blood pressure
- run blood tests for thyroid stimulating hormone (TSH),T4 and T3, antithyroglobulin (anti-Tg) antibodies and antithyroid peroxidase (anti-TPO) antibodies
- use thyroid ultrasound to measure the size, shape and texture of the gland and to detect any nodules that may be present
- perform a CT scan to measure thyroid function
- use fine needle biopsy to diagnose nodules or identify tissue change
Treating thyroid disease
Thyroid disease generally requires lifelong management. Your GP may refer you to an endocrinologist, who is a thyroid specialist. Regular blood tests and ultrasound scans may be necessary to monitor your thyroid function or thyroid hormone levels.