Your thyroid is a gland in your neck. It produces hormones that help regulate the body's metabolism.
The main hormones are triiodothyronine (T3) and thyroxine (T4).
An underactive thyroid gland is where your thyroid does not produce enough hormones. It is also called hypothyroidism.
Symptoms of an underactive thyroid
Symptoms of an underactive thyroid are similar to symptoms of other conditions. They usually develop slowly, so you may not notice them for years.
Non-urgent advice: Contact a GP if
you have symptoms of an underactive thyroid, including:
- tiredness
- weight gain
- depression
- feeling the cold more than usual
- dry skin and hair
- muscle aches
Symptoms of an underactive thyroid
Diagnosing an underactive thyroid
Your GP can check how well your thyroid is working by doing a blood test. This will measure the level of hormones in your blood.
Diagnosing an underactive thyroid
Who is at risk of an underactive thyroid
You may be more at risk of an underactive thyroid if you:
- are a woman age 60 or over
- had thyroid problems in the past
- have a family history of thyroid problems
- have other conditions related to your immune system, such as type 1 diabetes or coeliac disease
- have too much iodine in your diet
- are pregnant or had a baby in the last 6 months
Some people are born with an underactive thyroid. This is called congenital hypothyroidism. It happens when your thyroid does not develop properly in the womb.
Treating an underactive thyroid
You are usually prescribed daily hormone replacement tablets.
Levothyroxine tablets raise the level of thyroxine (T4) in your blood.
There is also a tablet called liothyronine that replaces T3 in your blood. But this is rarely used.
You'll have a blood test once a year to check your hormone levels.
Levothyroxine starts working immediately. But it may be several weeks before your symptoms start to improve. Most people need to take these tablets for life.
If an underactive thyroid is not treated, it can lead to complications.
Treating an underactive thyroid gland
Causes of an underactive thyroid
You cannot prevent your thyroid from becoming underactive.
It is usually caused by:
- a problem with your immune system
- damage to your thyroid during treatment for an overactive thyroid or thyroid cancer
Content supplied by the NHS and adapted for Ireland by the HSE
