The thyroid is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck.

The function of the thyroid is to make thyroid hormone, which is secreted into the blood and then carried to every tissue in the body. Thyroid hormone helps the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.

The thyroid is one of the most important areas to look at to improve energy and overall health, and yet is probably the most ignored and poorly treated gland in the body. Thyroid dysfunction often goes undiagnosed.



The thyroid produces two major hormones: triiodothyronine (T3) and thyroxine (T4).

Thyroxine or T4 is produced by the thyroid gland under regulation from the hypothalamus and pituitary gland.

The feedback loop signals to the hypothalamus to release thyrotropin-releasing hormone (TRH), which then

stimulates the pituitary gland to release the thyroid stimulating hormone (TSH).

The 4 stands for 4 iodine molecules that are attached to it. To activate T4 it is converted to T3.

We have enzymes that remove one of the iodine molecules and make T3.

T3 is a second thyroid hormone that is produced by the thyroid gland, but also in other tissues through

deiodination (enzymatic conversion) of T4. T3 helps maintain muscle control, brain function and development,

heart and digestive functions. It also plays a role in the body’s metabolic rate and the maintenance of bone health.

Although these are the two main hormones produced by the thyroid, when investigating the health and function of the thyroid gland your health care professional would normally test one (possibly two) hormone, called TSH, to diagnose thyroid dysfunction.


When the thyroid is not functioning optimally, a cascade of hormonal events takes place affecting several glands and hormones of the endocrine system and

all the physiological processes they regulate. The end result is one of two main types of thyroid condition: hyperthyroidism or hypothyroidism.

The main focus of this blog is hypothyroidism, also called underactive thyroid.


According to the National Institute of Health (NIH) hypothyroidism, is when the thyroid gland doesn’t make enough thyroid hormones to meet your body’s needs.

The prevalence of underactive thyroid is 2% in the UK and seems to be more common in women.


The signs and symptoms of hypothyroidism vary from person to person. The severity of the condition also affects which signs and symptoms appear and when.

Because many of the symptoms are so common and linked with other diseases, they can be difficult to identify.

The most common signs and symptoms of hypothyroidism include:

  • Thinning hair or hair loss
  • Puffy and sensitive face
  • Depression
  • Constipation
  • High cholesterol
  • Oedema
  • Fatigue
  • Mental fogginess and poor memory
  • Poor vision
  • Weight gain
  • Poor circulation and numbness in the hands and feet
  • Feeling cold
  • Chronic digestive problems
  • Dry/brittle hair and skin
  • Morning headaches
  • Muscle stiffness, aches and tenderness
  • Fertility difficulties and menstrual changes
  • Hoarseness
  • Decreased sweating


The major causes of hypothyroidism include:

Nutrient deficiency

Zinc is required for the synthesis of thyroid hormone.

Selenium is required to convert T4 (inactive thyroid hormone) into T3 (active form of thyroid hormone).

Selenium is also important for the protection of the thyroid cells from oxidative damage during thyroid hormone synthesis from iodine.

Vitamin A, B, C, and tyrosine are also crucial to healthy thyroid function. Deficiencies of these nutrients can lead to the development of hypothyroidism.


Iodine is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine.

Iodine is present naturally in soil and seawater. The iodine concentration of water and foods is highly variable. Seaweed (such as kelp, nori, kombu, and wakame)

is one of the best food sources of iodine. Other good sources include fish and other seafood, as well as eggs. Iodine is also present in human breast milk and infant formulas, added to processed foods as iodized salt, and available as a dietary supplement.

Both iodine deficiency and iodine excess are associated with an increased risk of thyroid disorders.

 When blood levels of TSH rise, the thyroid gland uses iodine to make thyroid hormones. However, when your body is low in iodine, it can't make enough of them.

To compensate, the thyroid gland works harder to try to make more. This causes the cells to grow and multiply, eventually leading to a goitre.

 If the underactive thyroid isn't caused by iodine deficiency, iodine supplements give no benefit and shouldn't be taken.

In fact, for some people with an underactive thyroid, too much iodine can cause or worsen their condition.

Effect of excessive iodine on the thyroid

Excessive iodine intake can alter thyroid function, although most individuals tolerate high dietary intakes of iodine remarkably well.

Hashimoto’s disease

Whilst iodine is necessary to make thyroid hormones, research has shown that excess amounts can actually exacerbate Hashimoto’s disease,

in which the body attacks the thyroid gland, progressively destroying its capacity to produce thyroid hormone.

This can result in hypothyroidism, particularly in those who are genetically predisposed to Hashimoto’s and may have certain “vulnerabilities”, such as a selenium deficiency.


Stress has a significant impact on your thyroid hormone function. This may be due to the effect of cortisol, which can block the conversion of T4 to the active thyroid hormone T3 and can also increase the unusable reverse T3 (rT3), further confusing the delicate balance of thyroid hormones that are so essential for optimal health.

Gut problems

Close to 80% of your immune system is located in your gut microbiome. Research suggests that poor gut health such as leaky gut syndrome and dysbiosisa (reduction in microbial diversity) will contribute to poor immune health. Also, 20 percent of your T4 is converted to the active thyroid hormone T3 in the gut, and an imbalanced, unhealthy microbiome can inhibit this process.

Toxin exposure

This is becoming more and more prevalent as our world has become increasingly toxic. Studies have shown that chemicals and heavy metals can cause an autoimmune response against the thyroid.

Other possible causes may include oestrogen imbalances, blood sugar dysregulation, insulin resistance and diabetes, use of artificial sweeteners, smoking, too much goitrogens (constituent of some foods) and low levels of vitamin A, iron, copper.


The reason isn’t clear, but sometimes, inflammation of the thyroid occurs after pregnancy. This is called postpartum thyroiditis. Women with this condition usually have a severe increase in thyroid hormone levels followed by a sharp drop in thyroid hormone production.

Most women with postpartum thyroiditis will regain their normal thyroid function but some may end up developing hypothyroidism.


The thyroid is the ‘sentinel’ for the environment. The function of the thyroid gland is designed to be induced or suppressed in response to changes in the environment.

As the environment changes, the function of the thyroid gland will change.

Key risk factors in the development of hypothyroidism:

Infections: Viral infections such as Epstein-barr can be a potential trigger for poor thyroid health, so an important consideration whilst investigating thyroid health.

Adrenal stress, which can manifest in many ways, can lead to autoimmunity, thyroid resistance, reduced conversion of T4 (non-active) to T3 (active) and disruption to the endocrine system.

Antigens/Gut function: Poor gut health can suppress thyroid function and trigger Hashimoto’s disease, and low thyroid function can lead to an inflamed and leaky gut. It’s important to mention gluten sensitivity and coeliac here, as research shows a strong link between hypothyroidism and gluten intolerance.

Medication: Thyroid physiology is very vulnerable to negative influences from many commonly prescribed and widely used medications.

Movement, sleep and relationships are also huge part of the functioning of the body and we cannot ignore the power of these lifestyle factors when investigating and treating hypothyroidism.


There is an ongoing debate about the diagnosis of hypothyroidism. The standard blood test available on the NHS currently looks at one, possibly two thyroid markers. One is TSH and the other one is T4. Testing for such a limited number of markers often leads to under-diagnosis or misdiagnosis and the patient often walks away thinking their thyroid function is fine.

In the current conventional system, when a patient is diagnosed with hypothyroidism they are often prescribed levothyroxine to counteract the symptoms of low thyroid hormone, regardless of the cause. But is it likely that that patient will go on to develop other health conditions because the underlying cause has not been addressed.

Patients with under active thyroid function have a much higher prevalence of obesity, diabetes, osteoarthrosis, osteoporosis, asthma, hypertension, dyslipidemia, infertility, mental health issues; low thyroid function is a symptom among a collection of other related symptoms with an underlying and unifying connection.

In order to successfully treat conditions that are directly linked to the thyroid, we need to understand what triggers the cascade of dysfunction. Only then can we begin to mitigate these triggers to start a path to healing.

This is where Claudia, your Health Care Professional at BioMed can help.

BioMed provides a wide range of diagnostics profiles which analyse all your body’s systems including thyroid function.

So, if you have concerns about your thyroid or any other health matters book a consultation now.

Following screening and in depth discussion Claudia will create a personalised health plan designed to your individual requirements.




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