Underactive Thyroid

What is an underactive thyroid?

Underactive thyroid is sometimes known as hypothyroidism. If you’re diagnosed with either, it’s helpful to know that they’re both the same condition but with a slightly different name.

Underactive thyroid and hypothyroidism mean that the thyroid gland can’t produce enough of a hormone called thyroxine. Thyroxine is the hormone that controls how much energy your body uses and is responsible for balancing your metabolism.

Think about it in terms of the battery on your smartphone. You may suddenly notice that even though you’re still using it for the same amount of time every day, the battery runs out quickly and needs more frequent charging to keep it going. If your body doesn’t have enough thyroxine, a similar type of thing happens and over time it can cause a range of unpleasant symptoms such as depression, fatigue, muscle cramping and weight gain.

Who gets an underactive thyroid?

It’s a condition that affects both men and women, though it’s more common in women.^[1] One reason for this is because underactive thyroid is known to be an auto-immune condition and these tend to be more prevalent in females than in males.

Primary underactive thyroid is much more common in women than men, about 8–9 times more. It becomes more likely with age. Having an underactive thyroid is usually most common in people aged over 60, but can occur at any age or stage of life.

In fact, children can develop it too, and it can be present from birth. It’s possible to be born with an underdeveloped thyroid, which will need to be corrected with treatment. This will usually be taken for life.

How common is it to have an underactive thyroid?

Having an underactive thyroid is actually a relatively common condition globally.^[2] There are very few countries across the world that don’t have any cases at all. Across all genders, it’s estimated that between 1-5% of the population globally has some level of hypothyroidism.

In some countries, cases are caused by diets that don’t contain enough iodine, which is found in foods such as seafood. Similarly, it can also occur when you don’t get enough dairy products in your diet too.

However, there are also other factors that increase susceptibility to underactive thyroid, such as genetic predisposition, your ethnicity and even social factors such as whether or not you smoke.

What causes an underactive thyroid?

There are a range of reasons why someone might have an underactive thyroid. It can be caused by many different factors.

You may be genetically predisposed to an underactive thyroid if one or more close blood relatives has it. It’s always worth talking to your family to see if there are any diagnosed cases that you might not have been aware of.

It can be caused by your thyroid gland being attacked by your immune system (otherwise known as an auto-immune disease). Auto-immune conditions are defined as illnesses in which the body’s cells attack each other. They can end up causing problems with other organs in the body. Conditions such as coeliac disease, lupus and type 1 diabetes are all examples of auto-immune illnesses.

There is also a condition called Hashimoto’s disease, which is classed as another auto-immune illness, which causes some of the same symptoms of an underactive thyroid. This can lead to later development of underactive thyroid.

When your thyroid gland is attacked in this way, it produces less of the hormone thyroxine. This is the hormone you need to keep your metabolism in check as it converts fat, carbs, and protein into energy. Your diet plays an important role in keeping your thyroid gland functioning, lack of iodine from foods such as fresh fish, seafood and dairy products like cheese and milk can affect it too.

In some very rare cases, it’s possible to be born without a properly developed thyroid gland, which can cause an underactive thyroid to develop. In these cases, it’s important to detect it as soon as possible and start treatment. This will usually be for life.

What are the symptoms of an underactive thyroid?

If your body doesn’t produce enough thyroxine, you might feel as if you’re going in slow motion, as your body has to conserve all the energy it needs in order to carry on day to day.

Therefore, you might notice symptoms such as:

• fatigue, which isn’t always improved by lots of sleep or taking a daytime nap
• feeling cold, or you’ve become more sensitive to temperature changes
• muscle aches and cramps
• dry and parched skin. You might find you need to use more body cream or moisturiser than you normally would
• tummy troubles such as constipation
• sexual issues, including loss of sex drive

Can underactive thyroid lead to other problems?

Many people who are diagnosed with an underactive thyroid start treatment and begin to feel better over time. It’s often a gradual recovery, but a noticeable one.

In some people who have the condition but perhaps don’t know they have it or have left it untreated, complications can occur.^[1] These include:

• Goitre. If your thyroid gland has to work extra hard to produce the hormones it needs then it can sometimes become enlarged. Once this happens it can cause what’s known as a goitre, which is a swelling of the thyroid. This isn’t usually a painful condition but it can sometimes lead to occasional problems with swallowing.
• Heart problems. In some patients, there can be an increased risk of heart disease if your underactive thyroid is left untreated. This is because an underactive thyroid can sometimes cause an increase in LDL cholesterol in the bloodstream.
• Myxoedema coma. This is an incredibly rare phenomenon, but it can cause feelings of intense cold and tiredness which can then lead to drowsiness and unconsciousness.
• Pregnancy complications. If you’re pregnant and have undiagnosed underactive thyroid then this can cause several issues which will need medical care. Anaemia (loss of iron), high blood pressure, muscle pain and weakness are all signs that shouldn’t be ignored. In rare cases, miscarriage and stillbirth can occur.

If you think you might have any of the signs and symptoms of an underactive thyroid, our clinicians can talk through treatment options with you and recommend the right medications for you.