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Links between Thyroid and Fatigue

by Victoria Tyler(more info)

listed in nutrition, originally published in issue 208 - August 2013

For many people one noticeable sign that the thyroid is not functioning properly is extreme fatigue. You may feel like it is extremely hard to wake up in the morning and that it is increasingly harder to work. Some patients need naps during the day.

If you are also finding it extremely hard to lose weight are cold and constipated this could also be a telling sign that you have problems with your thyroid.

Stress image 

What does the Thyroid Do?

The thyroid gland is regulated by Thyroid Stimulating Hormone (TSH).

TSH is produced by the pituitary gland and its job is to send signals to the thyroid to take up iodine. The thyroid is then able to produce two forms of thyroid hormone called Triiodothyronine (T3) and Thyroxine (T4) that are released into the bloodstream. Most of the T4 that is released is eventually converted to T3, and it is this thyroid hormone that is active throughout the body [1].  

The Thyroid hormones control practically every cell in the body. They affect metabolism, and regulate our body temperature and our digestive system.[4].   


A common condition associated with an underactive thyroid is hypothyroidism. 

The most common signs of hypothyroidism are:[4]

  • Fatigue
  • Intolerance to the cold
  • Constipation
  • Weight gain or inability to lose weight
  • Dry skin
  • Hair loss
  • Hair loss from the outer part of your eyebrows
  • Brittle nails

What are the Causes of an Underactive Thyroid?

There is certainly a genetic link to thyroid problems.  Low-calorie dieting, pregnancy and menopause can also be a factor in an underactive thyroid.[3]  

Fluoride may block iodine receptors, reducing the thyroid’s ability to uptake iodine. Mercury from fish and mercury fillings may also be a problem.  This is because Mercury can prevent proper conversion from T4 to T3. Also if you are under a lot of stress, you may find that your thyroid is not functioning properly.[3]

How to test for an underactive Thyroid

If you are experiencing symptoms of an underactive thyroid, the first thing to do is have your TSH (thyroid stimulating hormone) levels checked by your GP.

You can do this via a blood test. If your results indicate that your TSH is elevated beyond the normal reference range, you will be most likely be told to take some medication such as Thyroxine.  In the UK, The TSH acceptable range is somewhere between 0.1 and 2.5.[3]  The TSH test remains controversial as it not sensitive enough to diagnose milder form of hyperthyroidism.[2,4]  Murray  and Pizzorno claim[4] that mild hypothyroidism is the most common form of hypothyroidism and so many patients are undiagnosed.  Other tests include the basal body temperature test.[5]  This test requires you to take your temperature on waking for 10 minutes.  You should do this for 3 consecutive mornings. Barnes considered (36.6 °C) or below was highly indicative of hypothyroid function.

Because of the shortcomings of standard serum blood tests used by GPs, many patients do not know that they have mild hypothyroidism.  Even though they do experience fatigue, they are told all is well. This is one of the problems with modern medicine. Patients are often solely diagnosed using test results and not by their clinical symptoms.[3]   If you are suffering from fatigue, constipation, hair loss, sensitivity to the cold and weight gain and your TSH levels come back as being ‘normal’ you may have an undiagnosed underactive thyroid and it would be a good idea to see a practitioner.

Urine Thyroid tests

A sensitive test  for hypothyroidism is a urine thyroid test.[6]  This Test will measure your free T3 and free T4 levels in your urine over a period of 24 hours. This test may be better able to reflect the function of the thyroid gland as it is spread over 24 hours and may be more reliable that standard TSH tests.[6]  If your results show that your T3 or T4 levels are too low this is an indication that your thyroid is not functioning adequately.[3]

If you do have low T4 this could be due to chronic stress, genetic defects, insufficient iodine or tyrosine deficiency or even mercury toxicity.

The Adrenal and Thyroid Connection

The thyroid gland and the adrenal glands work together and many of the symptoms of hypothyroidism go hand in hand with a poor adrenal output. Therefore many patients who have an underactive thyroid also have low adrenal reserve. If the thyroid hormone is not being produced properly then the adrenals are called upon to produce more cortisol. Over time this situation can produce what Dr Wilson coined ‘adrenal exhaustion’.[7]

Adrenal exhaustion refers to constant fatigue as well as a poor response to stress and is the result of poor adrenal reserve. Many patients tend to find that their immune system is very low and frequently get colds and infections. When they do get ill, they find that even the smallest cold takes forever to shrug off.  Some patients also find that they become intolerant to the cold and to heat. Poor absorption of nutrients of food is also common resulting in deficiencies in hydrochloric acid and complaining of digestive complaints such as IBS and bloating. Another symptom of adrenal fatigue and hypothyroidism is that the Achilles reflexes are also slow.[3]

If you suspect you have an adrenal problem, it is important to try and correct this first.  Some patients who take Thyroxine find they don’t feel any better even after taking medication.This is because the conversion from T4 to T3 is dependent on the action of some enzymes. If you are experiencing low adrenal output this conversion from T4 to T3 is made very difficult, and toxicity[3] can occur with the body unable to convert the supplementary thyroid hormone (T4).

Natural Approaches

If you are experiencing many of the symptoms of an underactive thyroid and your urine thyroid test indicates you have low T3 or T4 there is a lot you can do naturally to help your thyroid.


The first thing to consider is exercise. Most patients do feel much better when they exercise regularly.  This means gentle stretching, walking and if possible getting out in the fresh air every day. If you suspect you have some form of adrenal exhaustion, it is not a good idea to exercise too intensely as you run the risk of depleting your adrenal reserve further.[4]


Nutritional deficiencies may be one of the causes of an underactive thyroid. The thyroid needs iodine to make thyroid hormone.  Iodine is found in fish, shellfish, cereals and grains and vegetables (although levels vary depending on the amount of iodine in the soil where the plants are grown). There is also iodine in cow's milk.

Good foods that contain iodine include fish and seafood as well as fruit and vegetables. Kelp tablets can also be taken.

Selenium is also important particularly for the conversion of T4 to T3 and is found in dairy, fish, shellfish, avocado pears wholegrains meat and nuts.

Your body also needs different amino acids to make thyroid hormone (amino acids are the building blocks of protein), especially the amino acid, Tyrosine. Tyrosine is found in soy, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, yoghurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds. Tyrosine supplements may also be beneficial.[4]

There are certain foods that should be eaten in moderation as they can slow down your thyroid. These are called  goitrogenic foods and include broccoli, cabbage, brussel sprouts, pine nuts, turnips, mustard, millet and soya.[3]

Natural Supplements

In addition to Tyrosine, Selenium and Iodine, Glandular extracts can be very helpful and do not require a prescription. It is important to see a practitioner to help you with dosage as too little may be ineffective while too much may lead to anxiety and palpitations.[3]

In conclusion, if a thyroid problem is suspected, it is a good idea to have a serum blood test to measure your TSH levels. However, if your test results come back normal and symptoms of fatigue do persist, it may be a good idea to  do a urine thyroid test.

It should also be remembered that in order to restore the proper functioning of the thyroid, it is essential to address the underlying causes. These may include stress, mercury toxicity, and nutritional deficiencies including selenium and iodine that prevent proper conversion from T4 to T3.  


1.Shomon MJ. The Thyroid Hormone Breakthrough. Collins. NY. ISBN 13-978-0-06-

079865-9. 2006.
2. Teitelbaum J. From Fatigued to Fantastic. Avery. NY. ISBN 1-58333-097-6 2001

3.Durrant-Peatfield B. Your Thyroid and how to keep it healthy. Hammersmith Press Limited. London ISBN 1-905140-10-X. 2006.

4. Murray, M. and Pizzorno, J. Encyclopedia of Natural Medicine, Three Rivers Press NY. ISBN 0-7615-1157-1. 1998.

5.  Dr Broda Otto Barnes  related basal temperature to thyroid function. (14 April 1906 – 1 November 1988).

6 Baisier W. Hertoghe J. Eeckhaut W. Thyroid insufficiency. Is TSH the only diagnostic tool? J Nutr Environ ed. 10:105-113. 2000.

7.Wilson JL. Adrenal Fatigue The 21st Century Stress Hormone. Smart Publications. USA. ISBN 1-890572-15-2 2007.


  1. Helen McCusker said..

    This is a good article, but most of the information i see is related to under active thyroid. I have and over active thyroid (Graves Disease) is there any information on this.

  2. E Chalmers said..

    Really useful article - thank you for including it - have recommended it to a friend already.

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About Victoria Tyler

Victoria Tyler BSc Hons MBANT received her BSc Hons in Nutritional Therapy from the University of Westminster in London. 

Victoria’s clinic is based in in central London, where she helps patients with gut disorders including IBS and food intolerances.  Victoria has also worked for major high food retailers including Pret a Manger, helping companies provide healthier foods. She also has worked with corporations, Universities and Nursery Schools. Victoria specializes in gut disorders and may be contacted on Tel: 0345 129 7996; her website is:


BSc HONS Nutritional Therapy, London UK

Professional Memberships
BANT- British Association of Nutritional Therapy
CNHC-Complementary and Natural Health Care Council
CNHC-Complementary and Natural Health Care Council

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