What is the thyroid gland?

Your thyroid gland is a small organ that sits at the front of your neck, just below your Adam's apple. It is part of your endocrine (hormonal) system.

Your thyroid gland makes and stores important hormones. These hormones help your body work properly.

The thyroid also has special cells that help control calcium levels in your blood. Blood vessels around the thyroid carry these hormones to where they are needed.

What does my thyroid gland do?

Your thyroid gland makes 2 hormones:

• Thyroxine (T4) is the main hormone made by your thyroid. In your body, thyroxine is changed into triiodothyronine (the active thyroid hormone).
• Triiodothyronine (T3) is also made and released by your thyroid.

These hormones are like messengers that help your body grow, stay active and use energy from food. They also help keep your body temperature steady. The thyroid gland stores these hormones in tiny sacs (follicles) and releases them when your body needs them.

The thyroid also has cells called C cells. These cells make a hormone called calcitonin. They work together with other systems in your body to keep your calcium levels balanced.

What medical conditions can affect my thyroid gland?

Different health problems can lead to too much or too little thyroid hormone production.

Some thyroid problems can lead to an enlarged thyroid gland (goitre).

Overactive thyroid

Hyperthyroidism is when your thyroid is overactive and produces too much thyroid hormone. It makes your body use energy too quickly.

It may be caused by:

• an autoimmune disorder called Grave's disease, which may lead to goitre
• nodules (lumps or growths) on your thyroid
• inflammation of your thyroid gland (thyroiditis)

Thyroiditis may cause a short period of high thyroid hormone levels before slowing down to levels that are too low.

Symptoms may affect your:

• energy and metabolism — weight loss, increased appetite and feeling too hot
• heart — fast or irregular heartbeat, palpitations and high blood pressure
• nervous system — nervousness, irritability, trouble sleeping and tremors (shaking hands or fingers)
• eyes — bulging eyes (in Graves' disease) and sensitivity to light
• skin and hair — warm, moist skin, thinning hair and brittle nails
• other — increased sweating, diarrhoea and muscle weakness

Underactive thyroid

Hypothyroidism is when your thyroid gland doesn't produce enough thyroid hormones. Your metabolism will slow down.

It may be caused by:

• the autoimmune disorderHashimoto's disease
• thyroid damage from certain medicines or treatments, such as surgery for thyroid cancer
• inflammation of your thyroid (thyroiditis)
• lack of iodine in your diet
• problems with your pituitary gland
• congenital hypothyroidism — a condition where the thyroid doesn't work properly from birth
• thyroid dysgenesis — when the thyroid doesn't develop normally during pregnancy

Symptoms may affect your:

• energy and metabolism — fatigue, weight gain and feeling cold
• heart — slow heart rate and low blood pressure
• nervous system — depression, difficulty concentrating (brain fog) and memory issues
• skin and hair — dry skin, hair thinning and brittle nails
• other organs — constipation, hoarseness, puffy face and swollen joints

How are thyroid problems diagnosed and treated?

Thyroid problems are diagnosed with different tests.

Tests that may help diagnose thyroid problems include:

• blood tests, especially thyroid function tests
• imaging tests, such as a thyroid ultrasound, to work out what is causing your thyroid problem
• a biopsy to check for thyroid cancer, if nodules are found

Treatment will depend on the type of thyroid problem you have. Treatment may involve medicine. In some situations, your doctor may recommend surgery, or radioactive iodine (RAI) treatment.

Resources and support

• The Australian Thyroid Foundation provides information and support for people with thyroid conditions.
• Hormones Australia offers support and resources on the thyroid gland and conditions affecting the thyroid.
• Hormones Australia can also help you find an endocrinologist (doctor specialising in hormonal problems).
• raisingchildren.net.au has a parent and children guide for if your child has problems with hormones.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.