Hypothyroidism, or an underactive thyroid, occurs when your thyroid gland doesn’t make enough thyroid hormone.
Your thyroid gland is found in your neck, at the base of your throat. It produces hormones (called tri-iodothyronine and thyroxine, or T3 and T4 for short) that help to regulate many of the body’s metabolic processes.
Common symptoms of hypothyroidism include:
- feeling weak, tired and fatigued
- increased sensitivity to the cold
- unexplained weight gain
- brittle hair and nails
- thinning hair
- dry, rough and/or cold skin
- pale appearance
- joint and/or muscle aches and pains
- poor concentration or memory
- a slow heart rate
- in women, irregular or heavier than normal periods
- low mood or depression
- having a hoarse voice
- goitre (an enlarged thyroid gland)
Many of these symptoms can occur for other reasons, so if you are experiencing symptoms of hypothyroidism, it is important to see your doctor so they can organise further investigations, including blood tests, to check your thyroid hormone levels.
In Australia, the most common cause of hypothyroidism is an autoimmune condition called Hashimoto’s disease, which develops when the body’s immune cells attack the thyroid gland. Other causes include surgery to remove the thyroid, radiation therapy, treatment for hyperthyroidism, certain medications and not having enough iodine in the diet. Secondary hypothyroidism is caused by problems with the pituitary gland, whose role is to produce thyroid-stimulating hormone (TSH) to signal the thyroid to produce thyroid hormones.
Hypothyroidism is treated with lifelong thyroid replacement medication. This is a synthetic (man-made) form of thyroid hormone (called thyroxine) given to replace the hormone your body is no longer producing. The dose needs to be carefully monitored and may need regular adjustment at the start of treatment to ensure the dose is right. Ongoing monitoring of your thyroid hormone levels is also important.
For more information, visit Health Direct: Hypothyroidism
- Health Direct: Hypothyroidism
- Better Health Channel: Thyroid-Hypothyroidism
- Australian Family Physician: Hypothyroidism Investigation and management