The Highs & Lows of Thyroid Function

An underactive thyroid can be difficult to detect even though it brings a wide range of symptoms, some mild, others debilitating. It is, however, possible to make a sure diagnosis if the complex pattern of cause and effect between hypothyroidism and its symptoms are understood.

The butterfly-shaped thyroid gland weighs between 8g and 40g and lies at the front of your neck, across your wind- pipe, between your breastbone and Adam’s apple. It has a wide range of functions.

It controls metabolism, promotes cell growth and assists in elimination of your waste through lymph.

It directly controls oxygen turnover in every cell in your body, regulates your temperature and helps control your hormone function. Your hormones direct nearly every system or process in the body, so a whole range of symptoms can be experienced when the thyroid gland is not functioning properly.

If your blood tests for thyroid function are normal but you continue to experience symptoms, you may have a more subtle form of hypothyroidism known as euthyroid sick syndrome (ESS), low T3 syndrome, non-thyroidal illness (NTI), functional hypothyroidism or subclinical hypothyroidism.

What’s interesting is that patients with high (hyperthyroidism) or low (hypothyroidism) thyroid function can complain of the same symptoms – fatigue, brain fog, hair loss, insomnia, heart palpitations, irritable bowel, muscle weakness and menstrual irregularities. The patterns of cause and effect between hypothyroidism and its symptoms are complex. Probably the most debilitating symptom of all is the deep-seated tiredness experienced as the result of slowing down of all body systems and organs. This constant fatigue can leave you depressed and anxious.


The ‘old’ way of thinking about hypothyroidism was ‘all about the gland’, without considering its context in the body as a whole. The new way of thinking, in the paradigm of Functional Medicine, is more along the lines of ‘at what level is there a problem?’ It recognises that the presenting symptoms may have many layers of causes. The thyroid gland can be inefficient or exhausted without being damaged or diseased. This mild dysfunction can be identified and addressed through suitable nutrition and supplementation.

Download Common Symptoms of Low Thyroid Function

If you are experiencing the majority of these symptoms, you may have an underactive thyroid gland (hypothyroidism).


There is a good deal of controversy surrounding testing for low thyroid function. In his address at the 14th International Symposium of Functional Medicine (May 2007),¹ Dr Alan B. McDaniel stated that in many cases blood tests for thyroid do not reveal what is wrong with you. A blood test is not always a reliable indication of functional hypothyroidism. A blood test will detect levels of hormones being transported in the blood at one particular moment, and not what the body is producing over time.

Medical practitioners often rely on the thyroid-stimulating hormone (TSH) reading as the primary diagnosis for low thyroid function. There is no doubt that TSH is integral to thyroid function. TSH is affected by many factors. Stress, lack of sleep and high serum cholesterol can increase TSH levels. Ageing, depression, anxiety and fasting can decrease them. The function of the hypothalamus, circadian rhythm, seasonal variations and changes in pulse rate all impact on TSH levels. A more complete strategy to assess thyroid function would include testing of all hormones produced by the thyroid gland – free T3, free T4, TSH, reverse T3 and total T3. A useful screening test for thyroid function, developed by Dr Broda Barnes, is to take your morning temperature over a period of time. A temperature consistently lower than 36.6 degrees Celsius indicates that your thyroid is not functioning optimally and requires further assessment. In my practice I use the 24-hour urine functional test to assess tissue levels of T3 produced over a full day.


This condition is often misdiagnosed as it shares the same symptoms as classic low thyroid symptoms. WTS is characterised by a sub-normal body temperature and patients usually have normal thyroid levels. It can be treated with herbal combinations or cycles of slow-release hormone T3. Refer to the article Wilson’s Temperature Syndrome by Dr David Nye in issue 89 November 2012 of Natural Medicine or visit:


Numerous causes including lifestyle, psychological factors, stress, environmental factors, poor diet and lack of nutrients, pregnancy, immunity, and poor detoxification should all be considered in the diagnosis and treatment of any reader presenting with symptoms of hypothyroidism.


1. McDaniel AB. Thyroid assessment: controversies and conundrums [CD-R] (2007).14th International Symposium of Functional Medicine, Institute for Functional Medicine, USA.

Further reading

  1. Durrant-Peatfield B. The Great Thyroid Scandal and How to Survive It. London: Baron’s Down Publishing, 2003.
  2. Holford P., and Burne J. Food Is Better Medicine Than Drugs. London: Piatkus, 2008.
  3. McDaniel AB. Thyroid Assessment: Controversies and Conundrums (CD-R) (2007). 14th International Symposium of Functional Medicine, Institute for Functional Medicine, USA.
  4. Mouton G. BCNH: Functional Hormonology. London: British College of Nutrition and Health, 2003.
  5. Mudd M. Why Am I So Tired? Is Your Thyroid Making You Ill? London: Thorsons, 2000.


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The Highs & Lows of Thyroid Function

Jacqueline Wildish
About The Author
- She graduated with distinction as a Nutritional Therapist from BCNH - UK College of Nutrition and Health in 2003. Jackie has worked at The Hale Clinic in the UK, where she gained experience in the field of enzyme deficiencies, particularly histamine intolerance. She now runs a private practice from Kingston-Upon-Thames, Surrey, specialising in the support of symptoms associated with hormonal imbalances, digestive disorders, chronic fatigue syndrome and fibromyalgia.