Hypothyroidism (Underactive Thyroid)

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What is an under active thyroid?

An under active thyroid - otherwise known as hypothyroidism, means that your thyroid gland is not producing enough of the hormones which are needed to regulate energy usage and to pace certain internal processes.

Unfortunately there is no known way of preventing an underactive thyroid, as the majority of cases are usually caused by either a damaged thyroid, or by the immune system launching an attack on the thyroid gland.

Symptoms

Key symptoms include aching muscles, depression, tiredness, dry skin and hair, constipation, and feeling more sensitive to the cold than usual. Because the majority of these symptoms all commonly occur as side effects of other medical conditions, hypothyroidism can be difficult to identify and diagnose straight away.

Some individuals may live with an undiagnosed case of hypothyroidism for a period of months before they recognise that their symptoms are continuing and decide to seek medical advice. When this does happen, the only accurate method of diagnosing the condition is a blood test to measure hormone levels within the blood.

If an underactive thyroid is left untreated for a prolonged period of time, more serious symptoms will develop as the condition advances. Though cases such as these are fairly rare due to the condition usually being identified at an earlier stage, later symptoms can include:

• anaemia
• deafness
• a hoarse or low-pitched voice
• thinned eyebrows
• slow heart rate
• puffy-looking face.

Individuals living with untreated hypothyroidism also stand an increased risk of developing a range of complications, with the risk of heart disease, premature labour, pre-eclampsia and low birth weight all heightened.

In very rare cases a longstanding low level of thyroid hormone within the blood could also lead to myxedema coma, a life-threatening loss of brain function.

Diagnosis 

If you are currently experiencing any of the key symptoms mentioned throughout, the best course of action is to pay a visit to your GP who will be able to refer you for a blood test in order to identify an underactive thyroid.

In a blood test, levels of the following hormones will be measured:

• Thyroxine (T4) – A low level of thyroxine is indicative of hypothyroidism.

• Thyroid-stimulating hormone (TSH) – This hormone is made in the pituitary gland, a small gland, no larger than a pea, located at the base of the brain. The gland itself is made up of three sections, the anterior lobe, the intermediate lobe and the posterior lobe, each of which produces certain hormones. The anterior lobe is the part of the gland which is responsible for the production of TSH (thyroid-stimulating hormone), and releases the hormone into the blood stream, which in turn stimulates the thyroid gland to make thyroxine. If the level of thyroxine in the blood is low, the pituitary will automatically release more TSH in a bid to stimulate the thyroid gland to produce more, meaning that raised TSH is a telling sign of an underactive thyroid gland.

In some cases, individuals may have a raised TSH, but T4 levels which are within the normal boundaries. This means that the body is making enough thyroxine but extra stimulation is needed in order to make the required amount. If this is the case, you may stand an increased risk of developing hypothyroidism in the future and your doctor may recommend repeat blood tests every so often so the condition can be identified promptly if it does develop.

Usually GPs are able to identify an underactive thyroid using either one or both of the above tests, though if levels of both TSH and T4 are low, a test of the pituitary gland may be carried out.

Who is at risk?

According to charity The British Thyroid Association, thyroid disorders could affect one in 20 people in the UK, 80% of whom are women.

Causes

Autoimmune thyroiditis

Though it is not the only cause of an underactive thyroid, autoimmune thyroiditis is thought to be one of the most common causes of the condition. In a healthy body, the immune system will usually produce antibodies which attack viruses, bacteria and germs and will generally defend the body from anything which may cause it harm. However, an autoimmune disorder is characterised by an overactive immune response. Which means that the body actually attacks its own tissues and cells.

In a person with autoimmune thyroiditis, the body will manufacture antibodies which will attach to your thyroid gland, preventing it from carrying out its proper function. This means that the thyroid gland is now unable to produce enough thyroxine to keep the body’s functions working at a stable pace, and thus hypothyroidism begins to develop. Experts believe that there is a trigger for autoimmune thyroiditis, though what it is exactly remains unknown. However, the autoimmune disorder is known to be more common in individuals with the following:

• A family history of hypothyroidism which is caused by autoimmune thyroiditis, or a family history of another autoimmune disorder such as type 1 diabetes, coeliac disease, anemia or Addison’s disease.
• A history of Grave’s disease, or thyroiditis.

• Down’s syndrome – Many individuals with Down’s syndrome develop hypothyroidism at some stage. Because of this many doctors recommend that all individuals with Down’s syndrome undergo annual testing for an underactive thyroid.

• Turner’s syndrome. An annual blood test to screen for an underactive thyroid is recommended for individuals with this condition.

• An enlarged thyroid gland, otherwise known as diffuse goiter.

Damaged pituitary gland

Any damage to the pituitary gland could mean that the anterior lobe, which is responsible for the production of TSH (Thyroid-stimulating hormone), is unable to continue making the hormone, leading to an underactive thyroid.

Goitre (swollen thyroid gland)

A goitre is a lump in the throat, the formation of which is the result of abnormal swelling of the thyroid gland.

The size of the lump will vary from person to person, remaining small and causing very few side effects in the majority of cases but occasionally developing into a large lump which can make both breathing and swallowing uncomfortable.

Autoimmune thyroiditis with a goitre is known as Hashimoto's disease, and this is considering to be the most common type of autoimmune reaction which leads to the development of an underactive thyroid.

Iodine deficiency

Your body requires iodine for the production of the hormone thyroxine, so a lack of iodine within your diet could be a contributing factor in the development of hypothyroidism. Iodine is a trace element which is found in seawater, rocks and some forms of soil. Healthy food sources include shellfish and fish. It can also be found in certain plant foods such as grains, although content will vary, as it is dependent on where the produce was grown. It can also be found in cows milk.

Other causes

Additional less common causes include the following:

• Radioactive treatment or surgery to the thyroid gland – An increasing number of individuals are opting to use treatments such as these to rid themselves of other thyroid problems. However, they can actually increase the likelihood of developing hypothyroidism.

• Medication side effects – A few medicines such as amiodarnone and lithium have been linked to hypothyroidism.

Treatment

Levothyroxine (thyroxine) is the medication which is prescribed to most individuals who have hypothyroidism. The medication will replace the thyroxine which your own thyroid gland is no longer producing, and in most cases this will improve symptoms in a short period of time.

Experts recommend that the tablet is taken on an empty stomach, preferably at the beginning of the day, before breakfast. The reason for this being because foods which are rich in either iron or calcium may inhibit the gut from fully absorbing the levothyroxine. For the same reason, it is also unwise to take the medication at the same time as calcium or iron supplements.

Sufferers often begin on a low dose of levothyroxine before it is increased gradually until the correct dosage is reached. During this stage, regular blood tests will be carried out for monitoring purposes.

Unfortunately, there is no known cure for an underactive thyroid and it is extremely rare for the condition to reverse itself. In some very rare cases, older children affected by hypothyroidism and pregnant women who develop a thyroid balance after having a baby do find the condition corrects itself, though for most others it will be life-long and medication will have to be taken indefinitely.

Because levothyroxine tablets are simply replacing a hormone which occurs naturally within the body, side effects are rare. Occasionally, individuals with angina may find that their pains worsen when they first begin taking levothyroxine, and if this is the case they should inform their GP as soon as possible.

Side effects may also be brought about if the dosage of levothyroxine is too high, which could potentially could result in the development of an overactive thyroid, irritability, diarrhoea, palpitations and an increased risk of developing osteoporosis.

Hypothyroidism and nutrition

As we know, the thyroid gland is responsible for the control of the body’s metabolism and the pace at which energy is burned, closely intertwining thyroid issues with the stability of our weight.

Typically, hypothyroidism is treated with a drug which is intended to replace the missing hormones the thyroid gland is no longer able to produce, so in most cases will provide the solution to any weight concerns.

If you have found that you have experienced sudden weight loss or weight gain then your first port of call should be your GP so that they can ensure you are taking the correct dosage of your medication.

If your GP does find that you are on the correct dosage then it may be that you simply need a little extra guidance to help you to keep your weight under control. It may be that you are struggling to lose the weight you gained prior to diagnosis, or it may be that some adjustments need to be made to your diet and exercise in order to minimise your symptoms.

Your GP may refer you to a registered dietitian who will be able to provide you with some extra help, or it may be that you have decided to seek help independently. The primary aim of a nutritionist or dietitian is to understand your habits and relationship with food so that they can formulate a personally tailored nutrition and exercise regime which is going to help you to keep your weight stable and under control.

If you would like to find out more about how a nutritionist could help you, please use our search tool to locate a qualified professional in your local area.

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