Signs and causes of an underactive thyroid

Some people have an underactive thyroid. This means that it’s not working as hard as it should be to do its job – which is to regulate certain hormones in your body.¹

Although you may have heard of your thyroid before, just how much do you really know about it?

This small, butterfly-shaped gland is located at the base of your neck.² It forms part of your endocrine system, which means that it plays a key role in balancing your hormones for biological processes, such as growth and development.¹

Principally, it’s concerned with producing the hormones that control your metabolism – the process that your body uses to transform food into energy.² To do this, your thyroid makes two hormones – thyroxine (T4) and triiodothyronine (T3).^1,2

Many people who have an underactive thyroid don’t actually realise that they have hypothyroidism.

Let’s explore some of the most common symptoms in more detail so that you know what to look out for:

If you can identify with any of these symptoms, particularly if you’re experiencing a combination, speak to your GP about the possibility of having an underactive thyroid.

For the majority of people with an underactive thyroid, their condition may be caused by an autoimmune disorder.^4,15

These are disorders that occur when your own immune system, which usually protects you and helps your body repair from illness and injury, can’t tell the difference between your own cells and unhealthy or foreign ones, causing it to attack your healthy cells instead.¹⁶

Other potential causes of hypothyroidism include:¹⁷

It’s also worth noting that pregnancy causes significant changes in the hormone levels produced by your thyroid, which can lead to temporary hypothyroidism.^18,19

Firstly, not everyone who has hypothyroidism will need to take medication. If your condition is very mild, or you have certain pre-existing conditions, the normal medicines prescribed for an underactive thyroid may not be suitable.

Fortunately, if you do need treatment for an underactive thyroid, it’s fairly straightforward.

Most people with the condition are recommended to start taking a daily hormone replacement medication called levothyroxine.²¹ This drug replaces the hormone that your thyroid isn’t making enough of (i.e.thyroxine), helping to stabilise your levels and control your symptoms.²¹

There’s no one-size-fits-all dose, and you may need to have yours adjusted a few times to find the one that works best for you. Once settled on the correct dose of levothyroxine, you’ll be monitored using annual blood tests to keep track of your hormone levels.

It's important to note that levothyroxine is only available on prescription. It also needs to be taken indefinitely, as without it, your symptoms will return. If you get pregnant, you’ll need to be more closely monitored, so it’s crucial that you speak to your doctor or midwife right away.²¹

It’s also useful to know that despite what some resources say, there are currently no specific foods or dietary supplements that are proven to be helpful in treating hypothyroidism. Nevertheless, eating a balanced diet that contains a comprehensive mix of nutrients can only benefit your overall health and wellbeing. Making sure you get enough sleep can also be helpful.

Living with an underactive thyroid can be quite debilitating, not to mention the risk of long-term complications.^4,5

If you’re concerned that you may have an underactive thyroid, such as because you’re experiencing some of the symptoms listed here, it’s always best to schedule an appointment with your doctor. They can arrange the necessary tests and help you to take back control of your health.

The advice in this article is for information only and should not replace medical care. Please check with your GP or healthcare professional if you think you have this condition.