Underactive thyroid

What is hypothyroidism?

The thyroid gland is a butterfly-shaped organ at the base of the neck, in front of the trachea (windpipe). It comprises two lobes (the butterflies wings) which are connected by a piece of tissue called the isthmus (the butterflies’ body).

Hypothyroidism (or underactive thyroid) is a hormone deficiency in which the thyroid gland does not produce enough of the hormone Thyroxine, which is used to regulate metabolism.

An underactive thyroid is more common in people aged between 40 and 50, and affects 10 times more women than men. It's estimated that 1 in 1,000 men have hypothyroidism, while the condition is much more prevalent in women, affecting 10 in 1,000 women.

What are the symptoms of an underactive thyroid?

Symptoms of an underactive thyroid can be easily misinterpreted as several other conditions. It can take a long time for symptoms to develop, which means you may not realise you have a problem for many years.

If you’re concerned you may have an underactive thyroid, speak to your GP about getting tested for this condition.

Your symptoms may include:

• Brittle hair and nails
• Constipation
• Decreased libido (sex drive)
• Depression
• Dry skin and hair
• Irregular or heavy periods
• Muscle aches
• Muscle aches, weakness and cramps
• Pain, numbness and tingling sensation in the hand and fingers
• Sensitivity to the cold
• Slowing of movements and thoughts
• Tiredness
• Weight gain

What causes an underactive thyroid?

The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto's thyroiditis. This autoimmune disease causes your body's immune system to attack the thyroid, damaging the cells and reducing the thyroids' ability to produce T3 and T4 hormones.

Another common cause of an underactive thyroid is over-response or over-use of treatments for hyperthyroidism, or overactive thyroid. These treatments are used to lower the amount of thyroxine and tri-iodothyronine. However, they can cause your levels to drop too low, resulting in hypothyroidism.

Surgery, such as a thyroidectomy, can cause a drop in thyroid activity. Thyroidectomy is the surgical removal of all or part of the thyroid. It is performed for thyroid cancer, goiter and hyperthyroidism.

How is an underactive thyroid diagnosed?

To find out whether you have hypothyroidism, a thyroid function test is required. A sample of blood is taken, from which your hormone levels are tested.

Speak to your GP about being tested for an underactive thyroid if you’re concerned.

In the UK, all babies are screened for congenital hypothyroidism during the early stages of their development.

What treatments are available for an underactive thyroid?

Typically, hypothyroidism is treated with daily hormone replacement tablets, such as Levothyroxine. These tablets increase the levels of thyroxine in your body. Levothyroxine helps to regulate the bodies metabolic rate which, over time, reduces the symptoms of hypothyroidism.

This treatment is lifelong, but shouldn't stop you living a normal and healthy life.

If left untreated, an underactive thyroid can develop into the following symptoms:

• Anaemia (iron deficiency)
• Hearing loss
• Increased risk of heart disease
• Lower-pitched and hoarse voice
• Puffed up face
• Slow heart rate
• Thinning or partly missing eyebrows

Prescription Doctor offers Levothyroxine as a treatment option for underactive thyroid, available in tablet form and dosages of 25mcg, 50mcg, 75mcg or 100mcg.

To find out more about Levothyroxine, including frequently asked questions, click here.

If you would like to order Levothyroxine, select the dosage and package type, and click Continue to Medical Questions.

Table of contents

What is hypothyroidism?

What are the symptoms of an underactive thyroid?

What causes an underactive thyroid?

How is an underactive thyroid diagnosed?

What treatments are available for an underactive thyroid?