Underactive thyroid (hypothyroidism)

Symptoms of underactive thyroid 

The function of the thyroid gland is to produce hormones. These hormones help regulate the body's metabolism (the process that turns food into energy). 

Many symptoms of an underactive thyroid (hypothyroidism) are the same as those of other conditions. So an underactive thyroid can easily be confused for something else.

Symptoms usually develop slowly. You may not realise you have a medical problem for several years.

Common symptoms and signs include:

• tiredness
• being sensitive to cold
• weight gain
• constipation
• depression
• slow movements and thoughts
• hoarseness or deepening of the voice
• muscle aches and weakness
• muscle cramps
• ‘pins and needles’ sensation in the hands
• dry and scaly skin
• brittle hair and nails
• reduced body and scalp hair (for example sparse eyebrows)
• puffy face, hands and feet (myxoedema)
• loss of libido (sex drive)
• pain, numbness and a tingling sensation in the hand and fingers (carpal tunnel syndrome)
• irregular periods or heavy periods

Elderly people with an underactive thyroid may develop memory problems and depression. Children may experience slower growth and development. Teenagers may start puberty earlier than normal.

If you have any of these symptoms, see your GP and ask to be tested for an underactive thyroid.

The thyroid gland 

The thyroid gland is a small butterfly-shaped gland in the neck. It is just in front of the windpipe (trachea).

One of its main functions is to produce hormones. These help to control the body's metabolism (the process that turns food into energy). These hormones are called triiodothyronine (T3) and thyroxine (T4).

Many of the body's functions slow down when the thyroid doesn't produce enough of these hormones.

When to see your GP 

Symptoms of an underactive thyroid (see above) are often similar to those of other conditions. The symptoms usually develop slowly, so you may not notice them for years.

You should see your GP and ask to be tested for an underactive thyroid if you have a combination of the following symptoms including:

• tiredness
• weight gain (unexplained)
• depression 
• being sensitive to the cold
• dry skin and hair
• muscle aches

The only accurate way of finding out whether you have a thyroid problem is to have a thyroid function test. This is when a sample of blood is tested to measure your hormone levels.

Treating an underactive thyroid 

An underactive thyroid can often be successfully treated by taking daily hormone tablets to replace the hormones your thyroid isn't making.

These hormone replacement tablets are called levothyroxine and  raise your thyroxine levels.

You'll usually need treatment for the rest of your life. However, with proper treatment, you should be able to lead a normal, healthy life.

If an underactive thyroid isn't treated, it can lead to complications, including:

• heart disease
• goitre (swelling of the thyroid gland that causes a lump to form in the throat)
• pregnancy problems
• a life-threatening condition called myxoedema coma (although this is very rare)

Who's affected

Both men and women can have an underactive thyroid, although it's more common in women. Children can also develop an underactive thyroid.

All babies born in Northern Ireland are screened for congenital hypothyroidism using a blood spot test when the baby is about five days old.

Causes of underactive thyroid 

There's no way of preventing an underactive thyroid. 

An underactive thyroid (hypothyroidism) is when your thyroid gland doesn't produce enough of the hormone thyroxine (also called T4).

Most cases of an underactive thyroid are caused by the immune system attacking the thyroid gland and damaging it.

Thyroid damage can also occur after thyroid or other neck surgery, or external radiotherapy for cancer treatment.

• Find out more about an underactive thyroid on the NHS website

More useful links

• How to use your health services