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 WHY ME?  The Causes and Triggers of Thyroid Dysfunction

By Robyn Koumourou (2001).


If you are anything like me, and have suffered with various conditions over your lifetime, you've probably asked yourself the question, why me? Where did this come from? What caused this to develop? Have I done something wrong? And, can I correct it or do something to get rid of it? 


Any person being diagnosed with a particular illness, may at some stage ask – ‘Why me?’ There may be many different answers in response to this question. However, finding the correct answer or actual cause can be enlightening and extremely important for understanding, managing and treating that condition. The causes for some diseases may never be found or completely understood, and this makes their treatment a little more difficult.


One hundred years ago the primary killers that reduced a person’s life span were malnutrition and infectious diseases. The average life expectancy for a man was 45 years of age. Today these primary killers have been virtually eliminated by an increased knowledge and understanding of nutrition and hygiene and also the development of antibiotics. This is the fundamental reason for increased longevity. Unfortunately, this increased longevity is now exposing those who live longer to the effects of old age such as heart disease, cancer and Alzheimer's. Cancer and heart disease, which were virtually unheard of 100 years ago, are now the number one killers of our modern age. We are now dealing with different epidemics and the quest is on to discover how to prevent or delay the inevitable. 


We are now living in the twenty-first century, and despite the millions of dollars spent on scientific research, pharmaceutical drugs and ‘miracle’ antibiotics, mankind continues to battle with human disease. What we need to understand is that ‘miracle drugs’ have their place but they will not rid the body of the elements that cause human disease. Mankind cannot create health through a pill. Disease comes easily, whereas good health requires knowledge and self-discipline.


Two Modern Enemies of our Time


The two modern enemies of our time, which we have created, are nutritional deficiencies due to poor dietary habits, and toxic poisons. Even though our food supply is plentiful, the production and processing of our foods has destroyed much of it’s nutritional content. Our modern lifestyles have created a demand for the ‘quick and easy and long lasting’. Our foods are full of chemicals, such as colourings, flavourings, preservatives, antibiotics and growth hormones, and of course, high in sugar and saturated fats. All in a quest for the best looking, best tasting and longest lasting foods. Products used in households, industries and agriculture all contain toxic substances that our bodies have to deal with day in and day out. Nutritional deficiencies and toxic poisons are two major factors that should be considered in contributing to human disease, as we know it. If we add to this poisonous soup, a deficiency of water and oxygen, and sprinkle in a few parasites, then we end up with a concoction that will make the body sick.

The human body is a living, healing and regenerating organism, and when given the right ingredients and environment, will function at it’s highest potential. Every cell is nourished by life giving blood and new living tissue is being constantly made. The body possesses amazing powers to heal itself with inbuilt systems to repair damaged cells and eliminate harmful intruders, toxins and accumulated waste. If we supply the body with a balance of the right elements - optimal nutrition, plenty of water and fresh air, adequate exercise and rest – and avoid the toxic and chemical pollutants in our environment as best we can, we are giving our body a better chance of warding off disease, and allowing it to function as it was intended.


Our modern society and life styles however, do not always provide the essential ingredients for good health and well-being. Toxins and chemicals surround us every day and avoiding them can be difficult. If a particular disease process has already established itself, a person can still take some positive action to improve their condition. It is up to the individual to increase in knowledge and understanding of how the human body functions, and to make appropriate changes where required. This all takes time and self discipline, but in the long run the benefits will far out weigh the sacrifices. 


So when it comes to thyroid gland dysfunction or metabolic disorders, there can be multiple causes, triggers and cofactors involved in it's evolution, and every person will be different. If you think back on your health history, it may give you some clues as to why you have developed abnormal thyroid function and poor bodily response to thyroid hormone influence. 


Overall, Hypothyroidism, in Australia, is clearly diagnosed in around 10% of the population, and Hyperthyroidism accounts for between 2-3%. Thyroid conditions affect women far more than men, with a female to male ratio around 5:1, however recent studies have indicated it could be closer to 15:1. Having said all this, it is highly likely that the statistics are much higher due to the fact that so many individuals remain undiagnosed, or misdiagnosed, or have borderline results, and are told they are 'normal', regardless of presenting with significant clinical symptoms.


So what are the main triggers of thyroid dysfunction? How many causes and co-factors contribute to the development of various thyroid diseases and the poor metabolism of thyroid hormones? Let us now take a look at the most common culprits in the world of thyroid dysfunction.

Causes of Disease in the Human Body
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Common Causes of Thyroid Dysfunction


Iodine Deficiency


Iodine deficiency is the most common cause of an underactive thyroid gland throughout the world. Iodine is the main raw material used by the thyroid gland to make thyroid hormones. In areas around the world where there are iodine deficient soils and a lack of dietary iodine, the majority of the inhabitants suffer from hypothyroidism and goitres (swollen thyroid glands). These regions are often referred to as ‘goitre belts’. 


Without sufficient iodine, the thyroid gland cannot produce adequate amounts of thyroid hormone. This deficiency is a particular problem for babies and children because thyroid hormone is needed for normal growth and brain development. Goitre, hypothyroidism, mental retardation and cretinism can result if the deficiency is severe and not corrected early enough.


Thyroid specialists and the World Health Organization have developed national programs in many countries to eliminate iodine deficiency world wide. The simple introduction of iodised salt or iodised vegetable oil to the diet prevents the risk of iodine deficient-related thyroid disease. Iodine deficiency has been rectified in most Western countries but is still a problem in many developing nations. Iodine deficiency is still considered the most common cause of preventable brain damage in the world.


In Australia, Gippsland, Canberra, Sydney and Tasmania are areas which have iodine deficient soils. This may contribute to some people developing mild hypothyroidism (low thyroid hormone production) if sufficient iodine is not part of their daily diet. This problem can be easily corrected by using iodised table salt or consuming foods containing iodine on a regular basis.


You would think that living in a wealthy nation, rich in food sources, that iodine deficiency would be unheard of, but many countries are experiencing a re- emergence due to lack of monitoring of iodine nutrition. Factors also include, strict vegetarian diets, and recommendations to reduce salt intake to prevent hypertension and heart disease. 


In the early 2000s, iodine deficiency began emerging in Australia after the dairy industry changed their cleaning products from iodine based disinfectants to chlorine based. The healthy levels of iodine residual usually found in all dairy products gradually disappeared and the Australian population was beginning to feel the effects of poorer thyroid function. Nation wide urinary iodine testing was initiated and the studies found that 50% of pregnant women and school children were mildly to moderately deficient in iodine. Endocrinologists and thyroid support groups raised the alarm, and health authorities approached the food industry so that breads and most flours were fortified with iodine to correct this health crisis. 


Iodine Excess


One of the most common triggers of thyroid dysfunction in developed nations is iodine excess. Over zealous consumption of iodine supplements, and eating large quantities of seaweed and seafood can cause a toxic rise in iodine levels within thyroid tissue. This can result in overactivity of the thyroid gland with the production of too much thyroid hormone circulating within the body, resulting in  the signs and symptoms of hyperthyroidism. Alternatively, iodine excess can trigger autoimmune thyroid diseases such as  Hashimoto's Thyroiditis and Graves' Disease, as toxic levels of iodine accumulate within thyroid cells and trigger an immune system response, especially in those with an inherited predisposition for thyroid disease. Iodine supplementation has been known to make autoimmune processes more aggressive and increase the destruction of thyroid tissue. A safe daily allowance of 150mcg is all the thyroid gland needs for healthy function.


Viruses and Infectious Agents


Unfortunately, in the medical arena, the role of viruses and infections in the development of thyroid conditions and other diseases, is often overlooked, or poorly understood. Acute viral infections or chronic systemic infections can be a trigger, cause or co-factor in many illnesses that plague our modern society, including thyroid dysfunction. When the body is dealing with stubborn foreign invaders, the immense pressure on the immune system as well as other bodily functions can disrupt metabolic pathways, trigger abnormal responses, and encourage autoimmune reactions. The answer to healing many illnesses today is not simply prescribing medications or using invasive treatments to deal with symptoms, but by actually addressing the triggers and causes in the first place. The thyroid gland is particularly sensitive to infectious agents which can infiltrate the cells of the gland and trigger immune system responses that begin to target thyroid tissue. Some of the culprits that can precipitate thyroid abnormalities is Epstein Bar Virus (Glandular Fever), parvovirus (B19), rubella, mumps, and retroviruses. Even when a person has recovered, these viruses, or their components, can still remain buried deep within thyroid tissue and other cells within the body. Once the autoimmune process is triggered, it may not resolve, and thyroid function may worsen with time, resulting in either Hashimoto's Thyroiditis, or Graves' Thyrotoxicosis. 


 A holistic approach that deals with supporting the immune system is all important in the treatment of thyroid diseases and any other conditions we are faced with. This would include, eradicating infectious agents, detoxifying the body, supporting gut and liver function, correcting nutritional deficiencies and promoting a healthy diet. This multifaceted approach, along side conventional medicine, has proven to be the most healing and restoring of the human body, which has the amazing ability to heal itself when given the right ingredients and provided the right environment. Some thyroid patients have recovered fully with a natural holistic approach, while others have needed a combination of therapies, both conventional and complementary to restore their thyroid function to normal. Again, it all depends on the causes, the type of conditions and the severity or length of illness. Thyroid conditions are treatable, they just need time, dedication and an individualized treatment program.




Just as with viruses and infectious agents, toxins and chemicals play a huge role in many disease states, and can alter cellular processes and place great pressure on the liver, the immune, endocrine and nervous systems. Living in a highly modern world we are surrounded by toxic chemicals. They are in the foods we consume, medications we take, makeup, hygiene, and household products. They are in materials, plastics and rubber, industrial and farming products, and we absorb these chemicals into our bodies everyday. All of these things can be a contributing factor in the development of a chronic illness, whether it is cancer, heart disease, diabetes, or thyroid disorders, they all result in inflammation, abnormal cellular activity and an immune system response. Toxins and various chemicals have been found within the cells of thyroid tissue and are implicated in the development of autoimmune thyroid disease.


Autoimmune Conditions


An autoimmune disease is one in which the body’s own immune system appears to be attacking good, healthy tissue or organs. The word autoimmune actually means “self-attacking”, but in reality, the immune system is responding to inflammation, altered tissue components, and foreign substances. The reason behind the development of such conditions is not completely understood, although, parasites/viruses, toxins and chemicals, and even excess iodine (in relation to thyroid), have been implicated in triggering an autoimmune response. It is known that the body's immune system has recognized a particular substance, tissue or tissue component as ’foreign’. 


Anyone has the potential of developing an autoimmune disease, however, you may be in a higher risk bracket if you have a family history of such conditions. This is usually referred to as a genetic tendency, or inherited predisposition. Genetic factors contribute to about 70-80% of the risk of developing autoimmune thyroid disease (AITD), while environmental factors contribute 20-30% in susceptible individuals. 


Under normal circumstances our immune system is brought into action at the first sign of an invader, such as, a virus or bacterial agent. When a foreigner is detected, your immune system cells (lymphocytes) produce specific antibodies, which act like armies, to attack and destroy that specific invader. Another group of lymphocytes are also primed to directly attack and infiltrate any cells that have been invaded. This is the body’s defence mechanism to protect us from infection and disease, and rid our body of harmful agents.


Hashimoto’s Thyroiditis - Chronic Lymphocytic Thyroiditis = Hypothyroidism


The most common cause of Hypothyroidism (an underactive thyroid gland), in developed nations, is the autoimmune condition Hashimoto’s Thyroiditis (HT), also known as Chronic Lymphocytic Thyroiditis. Thyroiditis simply means inflammation, while 'Hashimoto' was named after Dr. Hakaru Hashimoto, a Japanese pathologjst in 1912, who discovered the antibodies related to this autoimmune condition. With HT white blood cells (lymphocytes) invade the thyroid gland and attack the tissue, causing inflammation. These lymphocytes also produce antibodies, which target thyroid cells and interfere with the production of thyroid hormones. This whole process causes a swelling of the gland and the destruction of functioning thyroid cells. The thyroid gland is then not able to produce enough thyroid hormone to maintain the body’s normal metabolism. As this condition progresses the signs and symptoms of hypothyroidism ('too little' thyroid hormone), and slow metabolism, develop. These symptoms can be mild at first, but with time can become quite severe and debilitating. The antibodies associated with HT are antithyroperoxidase antibodies (abbreviated as TPO Ab) and antithyroglobulin antibodies (abbreviated as Tg Ab). For someone diagnosed with hypothyroidism or displaying classic symptoms of this disease, a simple blood test can determine the presence and levels of these antibodies. If the results are positive, a doctor can then confirm the diagnosis of an underactive thyroid gland caused by Hashimoto’s thyroiditis. However, it is not uncommon for a person to suffer for years with autoimmune hypothyroidism, and present with no antibodies in their blood serum. In these cases, a fine needle biospy can reveal the underlying autoimmune disease and infectious agent, but unfortunately most doctors will not go this far to correctly diagnose and treat a patient's condition. 


Graves' Disease - Autoimmune Thyrotoxicosis = Hyperthyroidism 


The most common cause of Hyperthyroidism (an overactive thyroid gland), is an autoimmune condition called Graves' Disease (GD), also known as toxic diffuse goitre. This condition was named after a 19th-century Irish physician, called Robert Graves, who first recognised and studied patients with enlarged goitres, tachycardia and associated hyperthyroid symptoms. In GD the activated immune system produces lymphocytes and thyroid stimulating antibodies (TSA, or TSI) that cause swelling and inflammation of thyroid tissue, and at the same time, stimulate the excessive secretion of thyroid hormones. This autoimmune process results in an overall enlargement of the thyroid gland, called diffuse goitre. Most patients with GD present with a swollen painful gland that can vary in size, from slightly enlarged, to greatly enlarged to several times it's normal size. In GD toxic levels of thyroid hormones push metabolic processes to an extreme and the signs and symptoms of hyperthyroidism result. For someone diagnosed with having hyperthyroidism or toxic goitre, a simple blood test investigating the presence of thyroid antibodies, and TSA, will confirm the diagnosis that their overactive thyroid gland is caused by autoimmune Graves' Disease. Treatment is needed to reduce circulating hormone levels to bring the body's metabolism back to normal. In some cases, if poorly controlled, a person's life may be endangered due to a 'Thyroid Storm' which requires emergency intervention due to extreme thyrotoxicosis. For others, the thyroid gland can eventually burn out, and then result in an underactive or non functioning gland. 


Some patients with GD also develop a condition called Graves ophthalmopathy, also known as Thyroid Eye Disease (TED). This autoimmune related condition causes patients to experience protrusion of the eyes (exophthalmos), eyelid retraction, inflammation and swelling of surrounding eye tissue, and can result in double vision, and occasionally loss of vision.


Toxic Nodules = Hot nodules


Around 50% of the population have tiny nodules on their thyroid glands, and the majority would never know it. Unfortunately some people develop more pronounced nodules and these are often associated with Hashimoto's and Graves' Disease. The word 'nodule' is simply a medical term used for 'lump' (cyst). The development of thyroid nodules can result for many reasons, such as iodine deficiency or excess, autoimmune processes, or poorly treated thyroid conditions. Nodules that are found on the thyroid gland are quite common and most are generally harmless and do not affect thyroid function, but occasionally a nodule may become toxic, or even malignant, so this would need to be investigated and appropriate treatment given. A toxic nodule, or hot nodule, is a lump of thyroid tissue that becomes overactive and produces excessive amounts of thyroid hormone independently of the rest of the gland. If no intervention is taken this toxic nodule may continue to grow and cause a rapid rise in circulating thyroid hormones levels, resulting in Thyrotoxicosis/Hyperthyroidism.


Some of the possible reasons for the development of nodules includes the following:

• Excessive stimulation of thyroid tissue by continuous elevated TSH levels due to poorly treated underactive conditions.

• Infiltration and bombardment of thyroid tissue by lymphocytes and thyroid antibodies, as seen in Hashimoto's Thyroiditis, or over-stimulation by thyroid stimulating antibodies (TSA), as seen in Graves' disease.

• Insufficient iodine in the diet, causing thyroid tissue to swell to trap more iodine to produce more thyroid hormone.

• Excessive iodine intake through diet or supplementation, resulting in toxic levels, overactivity of the gland, or initiating/aggravating autoimmune processes.

• Trauma or damage to thyroid tissue.

• Foreign material deep within thyroid tissue stimulating immune response.

• Thyroid cancer growth due to absorption of radioactive substances, or due to genetic predisposition to various thyroid cancers.


Whatever the reason for the development of thyroid nodules, it is wise to have them investigated. Treatment protocols should be initiated if these nodules become a problem, or press on the internal structures of the neck, making breathing or swallowing more difficult. Surgery is sometimes required depending on the cause or severity of the nodule. However, the majority of nodules are harmless and don't require any intervention, and many shrink or disappear on their own when thyroid hormone levels are optimized for a patient.


Postpartum Thyroiditis or Thyrotoxicosis


Pregnancy and childbirth is a key time of hormonal shifts, and has been found to be a trigger for the development of autoimmune thyroid disease. Abnormalities in thyroid function may present themselves during pregnancy, but become far more pronounced after childbirth when the immune system bounces back with aggression and stimulates the over production of autoimmune antibodies that attack thyroid tissue. Postpartum Thyroiditis (PPT) and Thyrotoxicosis can occur within the first six months after delivery, and are usually the result of autoimmune thyroid disease. In 10% of pregnant women positive thyroid antibodies have been found at 16 weeks’ gestation. Transient hyperthyroidism or hypothyroidism often occur until the thyroid gland resumes normal function over several months. Occasionally, a short-lived period of overactivity of the thyroid gland occurs, followed by underactivity, which also resolves with time. The symptoms that arise during this period are often attributed to postpartum depression or “maternal blues”, and thyroid hormone imbalances are often overlooked and not considered as a causative factor. In the majority of cases treatment for PPT is not necessary due to it's transient nature, and thyroid hormone levels usually normalize within 12 months. However, in around 50% of women with positive thyroid antibodies, the autoimmune attack on the thyroid gland progresses, symptoms worsen, and a more permanent condition takes hold. In these cases, life-long thyroid hormone replacement may be required.


Acquired Hypothyroidism


Another common cause for the development of an underactive thyroid gland is the result of treatment given for another thyroid condition, in particular, patients treated for Graves’ disease (an overactive thyroid gland), and thyroid cancer. For those suffering with hyperthyroidism due to Graves' disease, anti-thyroid medications like Carbimazole, or PTU, may be required to reduce the thyroid's ability to produce thyroid hormones, thus reducing circulating thyroid hormone levels. In more severe cases a patient may require RAI; radioactive iodine ablation, or surgery, to remove or destroy functioning thyroid cells. With these types of treatments the likelihood of ending up with an underfunctioning thyroid gland is quite high, leaving the patient with inadequate thyroid tissue to maintain normal circulating hormone levels. Thyroid hormone replacement will then be required to return hormones to optimal levels to maintain bodily functions. Finally, patients diagnosed with complicated toxic multinodular goitres, or thyroid cancer, often have their entire thyroid glands removed, and this ‘acquired’ form of hypothyroidism becomes inevitable. Life-long hormone replacement will then be required for long term health and wellbeing.


Congenital Hypothyroidism


Although thyroid disease occurs less frequently in children than in adults, the signs and symptoms can be similar. However, there are a few important differences that need to be brought to light.


Congenital hypothyroidism is a disorder that affects infants at birth, and occurs in about 1 in 3,500 live-born babies. In most cases it is characterized by the loss of thyroid function, due to the thyroid gland failing to develop normally. In some cases, the gland is totally absent. About 10% of cases are caused by either an enzyme defect leading to deficient hormone production, iodine deficiency or a brain pituitary gland abnormality. If the diagnosis is delayed and immediate treatment not given, congenital hypothyroidism can lead to defects in growth and development, impaired neurological function, physical deformities, and severe mental retardation (cretinism). 


Fortunately, routine testing for thyroid function in newborns has been mandatory in Australia since 1976. Within the first week of life, a heel prick blood sample is taken to test for a number of conditions including hypothyroidism. If any abnormality is found, a repeat blood sample is taken. If this confirms congenital hypothyroidism, the infant is immediately given thyroid hormone replacement therapy (T4 – thyroxine). Normal growth and development should then continue, with no adverse affects on the child’s physical and mental development and capacity.


Congenital Thyrotoxicosis


Congenital neonatal thyrotoxicosis is a rare transient form of hyperthyroidism in newborns, lasting up to three months or more after delivery.  It is due to the passage of maternal thyroid stimulating antibodies through the placenta, and can cause substantial neonatal morbidity or death if left untreated. Graves' disease (GD) in pregnant women complicates 0.1% to 0.2% of pregnancies, but congenital thyrotoxicosis only occurs in one in 70 of these pregnancies, independent of a mother's disease status or levels of antibodies. These infants are successfully treated with propranolol, oxygen and antithyroid medication to resolve cardiac and systemic symptoms, and normalise circulating thyroid hormone levels. 


Subacute Viral Thyroiditis


This condition, also referred to as de Quervain’s thyroiditis, results from a viral infection of the thyroid gland, which can cause temporary imbalances in thyroid hormone levels. Most people with subacute thyroiditis improve within 3-6 weeks, depending on the intensity of the viral attack. It can vary from one individual to the next, from very mild to quite severe. The most common features include pain and tenderness of the thyroid gland, accompanied by flu-like symptoms. A transient period of hyperthyroidism usually occurs, with an elevated ESR (Erythrocyte Sedimentation Rate), indicating acute inflammation due to infection. This is often followed by a temporary drop in thyroid hormone levels, and then complete recovery. Occasionally, a person may be left with permanent hypothyroidism if significant numbers of thyroid cells are damaged, and replacement therapy may be required if the thyroid gland cannot regenerate sufficiently through good diet and nutrition. 


Sick Euthyroid Syndrome


Sick euthyroid syndrome relates to a temporary hypothyroid condition that results from a person suffering with a severe non-thyroid illness. The stress upon the body causes a temporary drop in the level of circulating T3, while the T4 and TSH levels remain relatively unchanged. The person is said to be euthyroid (normal thyroid function), even though they do experience temporary underactive symptoms. Once they recover from the illness that has befallen them, their thyroid function returns to normal, and all symptoms related to their thyroid gland and tissue response resolve.


Pituitary or Hypothalamic Malfunction


Whilst uncommon, there are other conditions that can affect thyroid hormone production or utilization. A malfunction of the pituitary gland can cause it to produce too much or too little TSH (Thyroid Stimulating Hormone). This in turn causes the thyroid gland to produce too much or too little T4 and T3. Generally, the growth of a tumour on the pituitary gland is the main cause of abnormal pituitary function. These tumours are usually benign and can be removed through surgical procedures.


Rarely, there may be a problem with the Hypothalamus. If the hypothalamus is functioning abnormally, the autonomic nervous system and the entire endocrine system (hormone secreting glands) will be affected. Major problems in numerous parts of the body will occur and this includes the thyroid gland. Hormone therapy that involves numerous systems will be required to normalise all bodily functions.


Endocrine and Hormonal Imbalances


Hormonal imbalances in any part of the endocrine system can have an influence on thyroid function. A thyroid condition may develop that is secondary to a malfunction with another endocrine gland. Imbalances with oestrogen, progesterone and testosterone (and oestrogen dominance) will have a direct impact on thyroid hormone levels and can result in thyroid dysfunction. Key times of hormonal shifts, such as, puberty, pregnancy/childbirth and menopause are often triggers in the development of thyroid abnormalities, and this includes the alterations in hormonal balance with taking oral contraceptives and hormone replacement therapy. Adrenal hypofunction (insufficiency), or those suffering with Addison's or Cushing's disease, are more at risk of developing thyroid conditions as a secondary problem. Therefore, treating the initial hormonal imbalance or condition will usually resolve any issues related to thyroid function. Having said this, thyroid gland conditions can also cause abnormalities in other endocrine glands, so clearly diagnosing the primary problem is important for what treatment protocols are needed. Often correcting and treating a thyroid condition will restore the normal functioning of other hormone secreting glands without any further interventions. 


Liver Dysfunction and Gut Health


An intimate and complex relationship exists between the thyroid gland and the liver when it comes to health and disease.  Thyroid hormones which are essential for normal growth, development and organ function regulate the metabolic activities within all cells, including hepatocytes, thus modulating liver function. The liver, in turn, metabolizes thyroid hormones (around 30-40%) and regulates their systemic effects. In clinical studies, patients suffering with various forms of liver disease often present with alterations in T3 metabolism, with a corresponding drop in cellular activity, while T4 and TSH levels remain normal. These patients experience hypothyroid symptoms at the cellular level due to poor liver function. On the other hand, the reverse is also true. Thyroid dysfunction, in more severe cases, leads to an elevation of liver enzymes and clinical abnormalities. When the thyroid gland is treated appropriately, liver function usually returns to normal.  Therefore, thyroid health depends not only on normal thyroid hormone production and release, but also on normal thyroid hormone metabolism, the transport and delivery of T3 to nuclear receptors, and on receptor distribution and function within the liver, kidneys and pituitary gland.

A strong link exists between gut health and most forms of human disease. Alterations in the composition of gut microbes - gut dysbiosis - has been found in many autoimmune conditions, including Hashimoto's, Graves' disease and thyroid cancer. Healthy gut microbiology not only has beneficial effects on immune system function, but also on thyroid gland function and cellular activity of thyroid hormones.  Issues arise with damage to intestinal walls, increased inflammation, proliferation of infectious agents, and poor absorption and availability of essential micronutrients to sustain normal thyroid hormone production and cellular activities. Therefore, therapeutic management and treatment of an individual's gut composition would be highly beneficial as a measure for prevention, and healing for the thyroid gland and general health.


Cellular Resistance or Poor Thyroid Hormone Utilization


With some individuals there can be a malfunction at the cellular level, where the cells of the body do not respond to or utilize thyroid hormones correctly. The receptor sites in cells may have a genetic defect that prevents thyroid hormones from linking in and hinders the activation of cellular activities. Poor enzyme function or inadequate transport of thyroid hormones across cell membranes may also hinder the hormonal messages from being received. The successful conversion of T4 into T3 within the cells, which mainly takes place in the liver, kidneys and brain, may also be hindered for a variety of reasons. When the body is not receiving sufficient amounts of active T3, the cell’s activities do not function normally and the person becomes hypothyroid. Blood hormone levels may appear normal while the cells of the body are starving for more T3. The problems with T4 to T3 conversion and thyroid hormone resistance are uncommon, and transport, enzyme and utilization abnormalities are difficult to determine, therefore these can be easily dismissed or overlooked. In these cases where a person presents with normal blood tests results accompanied by significant hypothyroid signs and symptoms, administering T3 as a treatment protocol can have positive results and return a person's metabolism to normal. 


Nutritional Factors and Deficiencies


The thyroid gland relies on sufficient nutrients for the production of thyroid hormones. Iodine is the main raw ingredient of T4 (thyroxine, containing 4 iodine atoms) and T3 (triiodothyronine, containing 3 iodine atoms). Therefore adequate iodine is needed in the diet, around 150mcg per day, for healthy thyroid hormone levels. The amino acid tyrosine is what iodine is combined with to make thyroid hormone precursors, so when thyroid hormones are needed by the body they are ready to be secreted into the bloodstream. 

Other important nutrients are also needed in sufficient amounts to maintain normal thyroid function.  The minerals zinc, iron, manganese and copper, folic acid, B group vitamins, and the antioxidants Vitamin A, C, D and E are all vital for thyroid hormone synthesis and the utilisation of thyroid hormones for cellular metabolism. Any deficiencies of these nutrients can lower the amount of thyroid hormones produced and mild symptoms of hypothyroidism may result. Zinc, copper and selenium in particular, are essential for the conversion of the thyroid hormone T4 into the active hormone T3 throughout the cells of the body.  Selenium deficiency has also been associated with a higher prevalence of thyroid autoimmunity, with elevated TPO antibodies. The same has been found with low Vitamin D levels. It is therefore vital that any nutritional deficiencies are corrected so that all organ systems, and the thyroid gland, are given the raw materials to function optimally. 




The over consumption of particular foods that contain isothiocyanates may also lower thyroid hormone levels and induce the symptoms of hypothyroidism. These foods are referred to as goitrogens because the substances they contain interferes with iodine uptake and can hinder the manufacture of thyroid hormones within the cells of the thyroid gland. They are found in foods, such as, broccoli, cauliflower, cabbage, brussel sprouts, turnips, spinach, radish, bok choy, kale, horseradish, and mustard greens. The cooking of these foods usually inactivates the goitrogens and lessens their effects. Excessive intake of soy products, millet, strawberries, and walnuts can also contribute to an underfunctioning gland. Soy, in particular, blocks iodine uptake within thyroid tissue and hinders the effects of zinc, and has also been found to interfere with the absorption of thyroid hormones for those on hormone replacement. Generally, goitrogens only become a risk factor when these foods form a major part of one’s diet, or the diet is also deficient in iodine. Extreme Paleo or Keto diet regimes could pose a problem for those susceptible to thyroid dysfunction, or for those suffering with hypothyroidism. Moderation and wisdom needs to be used. 


Various nutritional and herbal supplements from pharmacies and health food stores contain substances that interact with thyroid hormones and thyroid medications. Those having an antithyroid effect include bugleweed, St John’s wort, aloe vera, green tea, horseradish, kelp, soy-based foods, L-carnitine, quercetin, motherwort, lemon balm, and lipoic acid. These substances would be okay for most people when consumed in moderation, however, they may have a negative effect on someone vulnerable to hypothyroidism, or when consumed in larger amounts. 


Similarly, there are substances that would best be avoided by those who have a tendency towards hyperthyroidism, as they have a stimulating effect and could increase thyroid hormone secretion. These include, celery seed extract, kelp and supplements with high iodine content, red food colouring, products containing caffeine, weight control pills, cough medicines containing pseudoephedrine, and other substances that stimulate metabolism which can further trigger or aggravate an overactive condition. Those suffering with an overactive thyroid could therefore benefit from substances that hinder thyroid hormone production, such as herbs like lemon balm, bugleweed and motherwort, which also calm the nervous system.


Drug Interactions


Particular drugs or supplements used in the treatment of other conditions have been documented to reduce the levels of circulating thyroid hormones, or prevent their absorption. This in turn may cause the symptoms of hypothyroidism to emerge or aggravate an existing thyroid condition.


In particular, Lithium, for depression, and the heart drug Amiodarone, increase the risk of developing hypothyroidism, especially with long term use. Lithium interferes with the production of thyroid hormones and Amiodarone contains massive amounts of iodine that can cause hyperthyroidism or hypothyroidism. The cholesterol lowering resins ‘cholestyramine’, antacids containing aluminium, and iron and calcium supplements, bind thyroxine in the gastrointestinal tract and prevent its absorption. It is suggested that these preparations be taken at least 4 to 6 hours after thyroxine.


People taking Prozac and some other antidepressant drugs, and those requiring insulin for Diabetes may need to adjust their medication dosages. Women on oral oestrogen therapy (and the contraceptive pill) need to regularly monitor their thyroid hormone levels. Oestrogen increases the protein that binds thyroxine in the blood and then less is available for the cells in the body. Therefore an increase in thyroxine may be required to correct the imbalance.


Finally, the over consumption of soy-based products or the taking of isoflavone supplements may hinder iodine uptake and affect absorption, thus increasing the risk of developing autoimmune thyroiditis and a goitre.




Stress, whether it is chronic or acute, physical or emotional, has a profound effect upon the body and mind, causing a cascade of chemical and hormonal reactions. Stress can come from internal or external forces, such as, infections, disease, allergies, injury, trauma, operations, pregnancy and childbirth, sleep deprivation, and general lifestyle with mental and physical demands. Any of these stresses can have an impact on thyroid function and immune system response, and may trigger the development of a thyroid disorder, or aggravate an existing thyroid condition. It is known that excessive stress hormones can activate dormant viral and bacterial agents that already exist within the body. Therefore, eliminating stresses, as best one can, from all areas of life is vital for overall health and wellbeing. 


Thyroid Cancer


As with many cancers, a combination of factors, such as, genetic predisposition, infections and toxins (which cause chronic inflammation and overload the liver), and nutritional deficiencies, all play a role in the development of disease, and this includes thyroid cancer. X-ray therapy used in the mid 1900's was found to cause malignant tumours on the thyroid glands of patients receiving treatment for other conditions. This aggressive therapy was then abandoned. Nowadays x-ray procedures are far safer, and greater precautions are taken.

The thyroid gland is particularly vulnerable to radiation, and radioactive iodine, which in past years and events caused high numbers of thyroid cancer in children and adults due to radioactive fallout from nuclear accidents, and testing of atomic bombs. Chernobyl had devastating effects on the surrounding population and is still being felt today. 

When it comes to the thyroid gland, any nodules, lumps or swollen lymph nodes in children and adults should always be investigated thoroughly. Nodules that continue to grow and those that are considered 'cold' or inactive are generally more suspicious. The good news is that most thyroid cancers are slow growing and usually fully self-contained within the gland, so in most cases infected cells can be completely eliminated from the body, and a person can live a long healthy life without it reoccurring. 




So when it comes to thyroid gland dysfunction or metabolic disorders, there can be multiple causes, triggers and cofactors involved in it's evolution, and every person will have their own unique story. Abnormal thyroid function will produce abnormal physical, emotional and mental symptoms, which can range from mild to severe! Everyone will be different, and therefore, will respond differently to treatment. There is no magic pill, or quick fix, as some have claimed. When a person is suffering with a thyroid condition, thorough testing and a careful analysis of clinical symptoms needs to be done. Any treatment protocol will need to be tailored to the individual and their unique set of needs and circumstances. This multifaceted approach should address the various causes that are found, so that the body is given everything it needs to function as optimally as possible, be restored, and heal itself. The good news is, thyroid conditions are treatable. It may take time, patience and dedication, but the effort is worth it for a long healthy future.


© 2001 by Robyn Koumourou

Thyroid Disorders | Thyroid Matters

Updated 2020



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