Dr Chinnadorai Rajeswaran, consultant endocrinologist explains about underactive thyroid or hypothyroidism. Please email, if you would like to learn more.

Underactive thyroid gland (hypothyroidism) results from the thyroid gland not producing adequate thyroid hormones.

Symptoms of hypothyroidism include:

  • Tiredness
  • Weight gain
  • Constipation
  • Muscle aches
  • Intolerance to cold
  • Dry skin
  • Infrequent and/or heavy menstrual periods
  • Infertility
  • Low libido
  • Thinning of hair
  • Fluid retention
  • Mental slowing
  • Low mood
  • Confusion
  • Hoarse voice.

Symptoms usually develop gradually over several years and hence people do not notice any difference initially. People seek help only when the symptoms get worse. Response to treatment is usually very good. However, untreated hypothyroidism can result in:

High cholesterol, coronary heart disease, heart failure, increasing confusion and rarely hypothyroid coma. Pregnant women with hypothyroidism, who do not have proper treatment may develop complications like premature labour, pre-eclampsia, miscarriage and/or abnormalities in the baby.

What are the causes of hypothyroidism?

Autoimmune thyroiditis

The most common cause for hypothyroidism is an autoimmune condition called autoimmune thyroiditis. Autoimmune thyroiditis with a goitre is called Hashimoto’s disease.

This means that your body is producing antibodies against your own thyroid gland leading inflammation and reducing the amount of thyroid hormone produced.

Autoimmune thyroiditis is more common in people who have a family history of underactive thyroid due to an autoimmune cause. It is also commonly seen in certain medical conditions like type 1 diabetes, pernicious anaemia, Addison’s disease, vitiligo, coeliac disease, Turners syndrome, Downs syndrome and several other auto immune conditions.

Underactive thyroid is also seen in people who have had:

·      Surgery

·      Radioactive treatment to head and neck

·      Medications like carbimazole, propylthiouracil, amiodarone and lithium

·      Pituitary problem

How is hypothyroidism diagnosed?

Blood test is done if there are symptoms of hypothyroidism. Blood test include TSH (Thyroid Stimulating Hormone) and FT4 (Thyroxine). In people with underactive thyroid, level of thyroxine is low, thereby the pituitary releases more TSH. So, high TSH indicates that the thyroid gland is not making adequate thyroxine.

Thyroid antibodies are requested if an autoimmune cause is suspected. If you have an enlarged thyroid gland, an ultrasound scan may be requested.

What is the treatment for hypothyroidism?

The treatment for underactive thyroid or hypothyroidism is usually to take levothyroxine or thyroxine tablets.  It is recommended that thyroxine is taken on an empty stomach, at least half an hour before breakfast. A number of medications interfere with action and absorption of thyroxine, these include: Calcium, carbamazepine, iron tablets, phenytoin, proton pump inhibitors like omeprazole, cholesterol lowering medication like cholestyramine, colestipol and rifampicin. If you are on any on these medications discuss with your doctor and ensure you have them at least four hours after you have taken thyroxine.

Always check with your pharmacist if you do need to take another tablet at the same time.

If you forget to take a dose of thyroxine, take it within 2-3 hours if you remember. If you do not remember, skip the dose for that day and take the next dose at the usual time. Never take two doses together. Please read below.

Taking too much thyroxine can lead to the following symptoms:

  • Increased risk of osteoporosis.
  • Increased risk of atrial fibrillation or AF.

It is therefore important to have thyroid function test at regular intervals and discuss with your doctor and take the appropriate dose.

Don’t feel well despite taking thyroxine regularly?

Most people feel better once they are on the right dose of thyroxine and TSH has returned to the normal range. It is important to understand there will always be some people who will not respond to thyroxine and will remain symptomatic despite normal thyroid function test.

If this is the case, you would normally be referred to a specialist (an endocrinologist). The endocrinologist would arrange some more tests to check if your symptoms are definitely due to hypothyroidism or due to some other condition.

There are several reasons why despite taking the prescribed dose of thyroxine you still do not feel right. Some of the thyroid related conditions include:

  • Poor compliance
  • Poor absorption
  • Drug interference
  • Secondary hypothyroidism
  • TSHoma
  • Thyroid hormone resistance

Occasionally a combination of T3 and T4 therapy may be discussed as an option in some people. Current guidelines do not recommend T3 or combination treatment for hypothyroidism as there is no good evidence that it is effective, and it may be harmful in some people.

 Liothyronine (including Armour Thyroid)

Armour Thyroid contains a combination of both T4 and T3. Armour thyroid is extracted from the thyroid gland of pigs. Armour thyroid has a significantly higher proportion of T3 than humans.

The NICE (National Institute of Clinical Excellence) clinical guideline advises not to routinely offer T3 for primary hypothyroidism, either alone or in combination with T4, or natural thyroid extracts, as there is insufficient evidence. NICE notes that natural thyroid extract is unlicensed for use in the UK [NICE, 2019].

The British Thyroid Association states that a small number of patients have symptoms which do not improve on levothyroxine. For these, a consultant endocrinologist may recommend a carefully monitored trial of liothyronine.

What is Subclinical hypothyroidism?

Some people have a slightly high TSH level but not high enough to warrant treatment. They however have symptoms suggestive of underactive thyroid. Endocrinologist will elicit a detailed family history, current symptoms and arrange for some blood tests including thyroid antibodies and decide if you would benefit from thyroxine.

It is always important to rule out any other medical conditions which mimic the same symptoms as underactive thyroid.

Treatment for hypothyroidism in pregnancy?

Pregnant women with hypothyroidism are treated with thyroxine. Thyroxine dose should always be monitored by an endocrinologist. Pregnancy can affect the amount of medication needed.  It is very important that TSH levels are kept within a strict range, as too high or too low levels can affect the baby.

Can hypothyroidism lead to excessive weight gain (obesity)?

Yes, when people do not have underactive thyroid treated correctly, they are likely to gain weight. However, some people may take the correct dose of thyroxine but still have symptoms of hypothyroidism and gain weight.

There are a number of reasons, why despite having correct and regular doses of thyroxine people are symptomatic. Poor absorption, intolerance to thyroxine, thyroxine resistance are some of the reasons, which needs to be investigated.

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Dr Chinnadorai Rajeswaran is a consultant Physician specialising in Endocrinology, Diabetes and Obesity. As a private endocrinologist he  has private endocrine, diabetes and weight loss clinics in Harley Street, London, Chennai (India), Claremont Hospital, Sheffield, Nuffield Hospital, Leeds and Simplyweight, Bradford.

He has face to face consultations with people from Barnsley, Rotherham, Chesterfield, Doncaster, Wakefield, Huddersfield, Bradford, Harrogate, Leeds, Sheffield, London and Chennai (India). He also offers video consultations.

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