What is the thyroid?

The thyroid is a gland in the neck, near the base of your throat. The thyroid gland makes hormones that help control some of your body’s metabolic processes, such as heart rate, blood pressure, body temperature and weight.

What is hypothyroidism?

In hypothyroidism, the thyroid gland does not make enough thyroid hormone.

The most common cause of hypothyroidism in Australia is Hashimoto's disease, or thyroiditis. This is an autoimmune disease, which occurs when the body’s immune cells attack the thyroid gland.

The other main causes of hypothyroidism are surgery that removes some or all of your thyroid, radiation therapy, treatment for an overactive thyroid (hyperthyroidism) and medicines, including lithium. It can also be caused by too little iodine in the diet, a problem with your pituitary gland, or by pregnancy.

Symptoms and signs

Hypothyroidism can develop over many years without showing any symptoms. When symptoms do appear, they may be quite varied and can include:

• tiredness
• being unable to stand the cold
• weight gain
• puffy and pale face
• brittle hair and nails, thinning hair
• dry, cool skin
• muscle pain
• constipation
• headache
• poor attention span or memory
• slow heart rate
• heavier than normal periods
• depression

Some people can have symptoms of hypothyroidism without any abnormality in their hormone levels. At other times, these symptoms may have different causes. If you are concerned about any of these symptoms, see your doctor.

Your doctor will check your neck to see if your thyroid is enlarged or has nodules, and will look for other signs of hypothyroidism such as a slow heart rate.

To diagnose hypothyroidism, a blood test is done to measure the level of your thyroid hormones.

Treatment

If you are diagnosed with hypothyroidism, you will most likely be treated with a medicine to replace the thyroid hormones. This medicine is a synthetic version of the hormone thyroxine, and in most cases you will need to take it for the rest of your life.

Once treatment has begun, it may take some time to get the dose right for you, and further adjustments may be needed as time goes by, so your hormone levels will need to be checked regularly.