Thyroid gland: metabolism, terms and functions

Thyroid gland

What is the thyroid gland and how does it work?

You’ve probably heard about the thyroid gland before, but do you even know what it is and what it does?! The thyroid is a butterfly-shaped gland that sits low on the neck, underneath your Adam’s apple and is wrapped around the windpipe.

Why is the thyroid gland so important? 

You might not have heard or known much about the thyroid gland before, so it’s understandable if you’re wondering why it’s so important.

Our thyroid gland secretes hormones that help regulate sexual functions, digestion, etc. However, the thyroid gland is different as it governs our heart rate, blood pressure, temperature, energy and metabolism. But it doesn’t end there. Although those are its primary functions, the thyroid can affect and interact with every single cell in our body.

Now can you understand why keeping the thyroid gland healthy and optimal is so important?!

Here’s a great analogy that’s helped me understand it better: imagine your body is a car. It needs fuel to function. Your thyroid gland is the accelerator which regulates how much fuel is used, when it is used and how it is used. If it detects that a particular area of the body needs more fuel (i.e. energy) it will send some extra. Similar to a car, once parts of our body stop working properly, our fuel efficiency also takes a hit, and we end up burning more than needed to keep up. This can explain why our body becomes tired and we suffer from fatigue.

Let’s look at some thyroid gland terms and functions 

A healthy thyroid gland produces the following hormones: T4, T3, T2, T1 and calcitonin.

T3 – triiodothyronine 

T3 is thought to play a key part in evaluating the health of your thyroid. It is the more effective and influential form of the two key hormones our thyroid gland is producing. T3 is much more effective as a thyroid hormone than T4 – four to ten times more in fact. T3 is also formed from the conversion of thyroxine (AKA T4) in tissues and cells. (but that process doesn’t always run smoothly)

T4 – thyroxine 

Your body produces plenty of T4, hence its name the ‘proliferator’. T4 is a storage hormone (meant for later use) and the primary hormone produced by our thyroid. T4 is meant to convert into the active hormone T3 in your body cells.

Thyroid gland and metabolism 

Staying on the car analogy, think of your metabolism as the speed setting. In layman’s terms, let’s think of the Thyroid gland as the master gland of our metabolism. The thyroid releases hormones that are critical in regulating your body’s temperature and the way your body processes and uses foods each day. Depending on its health, it can either use up the energy given through food and nutrients very quickly or very slowly. Our T3 and T4 hormones also have a hand in this. Your metabolism can work optimal or inefficient/dysfunctional. When your metabolism is dysfunctional, your basal metabolism (calories we burn to stay alive, without any extra activity) is reduced. This new metabolic set point leads to more fatigue, fewer muscles, more weight, increased issues and so on.

Hypothyroid versus hyperthyroid 

So far, we’ve discussed the causes of hypothyroid and possible ways to manage it, on the opposite end of the spectrum is hyperthyroid. A hyperthyroid occurs when our thyroid becomes too active. Treatment for hyperthyroidism is a lot more intense and may involve radiation therapy or medication that brings thyroid function down, sometimes permanently. Always try natural ways first and incorporate a lifestyle that lowers inflammation prior to taking such drastic steps.

Micro and macronutrients 

Macronutrients and micronutrients are specialised functions, related to our metabolism.

Examples of macronutrients are fats, proteins and glucose, which is where we get most of our energy from. Our thyroid decides how much macronutrients are burned and where it is needed most. It also metabolises the protein and sugar in our body and processes micronutrients such as calcium, magnesium and phosphorus. Micronutrients are connected to a thyroid known as the parathyroid glands, which regulates the levels of minerals in our system.

Macro and micronutrients are controlled by the thyroid, which makes them essential for energy and strength.

The conclusion of the role your thyroid gland has in your body 

Hopefully, you’re beginning to get a picture of the kind of role the thyroid gland has in your body and how incredibly important it is that it remains healthy and functioning. The thyroid is responsible for allocating micro and macronutrients across the

It decides what organ, muscle, bone, or brain cell in the body needs fat, blood glucose, protein, calcium and magnesium! The thyroid gland plays an even bigger role within our vascular system as it correlates to a heightened heartbeat and cardiac output. It also increases and supports our breathing, which then helps oxygen flow through our bloodstream.

Thyroid hormone levels also play a role in the nervous system, as it helps to create greater awareness, mental focus, and alertness by increasing sympathetic response. Finally, a well- balanced thyroid contributes to uterine health in women, which is thought to improve fertility and reproduction. Maintaining a healthy level of T3 and T4 is essential to ensure our organs and systems are functioning properly.

A healthy thyroid means that your energy is being used correctly leaving you full of vitality and zest. It also means that the other functions that it affects are in working order. An unhealthy thyroid, however, can lead to all sorts of problems including chronic fatigue, depression, amongst many other.

Here are some hypothyroidism causes: 

RT3 – Reverse triiodothyronine 

RT3 is a form of inactive T3, produced during stress episodes (flue, chronic stress, surgery, accidents, certain drugs, etc) where the body needs to sacrifice energy for fixing problems. Remember the T3 and T4 thyroid hormones that we discussed earlier? If these hormones do not convert well it can lead to all sorts of health issues. Then, sometimes too much T4 is converted which can lead to ‘reverse T3’, also known as RT3. RT3 can inhibit thyroid function, leading to an underactive thyroid.

Proinflammatory antibodies 

The chapter on inflammation covers all the information you need but to put it simply; inflammation is triggered when there is a perceived attack on the body or immune system. At its worst, it can lead to chronic inflammation, where the body continuously attacks itself, even when there is no threat. This is a situation where auto-immune diseases start surfacing and begin to attack the thyroid or any other gland or body-part.

Unhealthy gut microbiome 

Sometimes when T4 is converting into T3, some of the hormones will not make it, transforming itself into thyroid sulphates and acetic acids. To correct this, the hormones will travel down to the digestive system where it can convert properly into T3 and increase thyroid function. Now, if you have an unhealthy gut or digestive system, this can inhibit the conversion of T3 leading to hypothyroidism.

Poor liver function 

The liver also plays a crucial part in T3/T4 conversion (80% of T4 is processed in the liver). Factors such as inflammation, excessive alcohol consumption, toxins and other liver-related illnesses will therefore have a knock-on effect on thyroid function and could even lead to hypothyroidism.

Poor nutrition 

Nutrients such as iodine are essential for a well-functioning thyroid. In fact, according to the World Health Organisation, an iodine deficiency is one of the biggest health issues plaguing the west. There was a time when iodine was naturally found in the soil, but unsustainable agricultural practices have led to it depreciating quickly. Small amounts of iodine can still be found in seaweed, kelps and iodized salts, but it’s probably better to take a supplement to ensure you’re getting enough. Low iron can also affect thyroid function as it is needed to transport the hormones to those areas that are lacking energy. This can also lead to anaemia which can make you feel tired and low on energy.


Dr Mark Hyman explains:

“One of the most important factors that lead to thyroid dysfunction is exposure to environmental toxins which act as hormone or endocrine disruptors and interfere with thyroid hormone metabolism and function. These pesticides then interfere with thyroid function and cause hypothyroidism. Heavy metals, such as mercury, can also affect thyroid function.”


By now you’ll have read enough about toxins and chemicals to know that they’re bad news, but did you know that they can have an adverse impact on your thyroid health too?

Stressful lifestyle 

Stress can make our body produce too much RT3, which can cause the thyroid to become inactive. Higher levels of stress can also cause the body to release cortisol which results in less T3 becoming available.

“There is an intimate interaction between stress hormones and thyroid function” explains Dr Hyman. “More stress taxes your adrenal glands, resulting in a less-than optimal thyroid.” It’s important to try and reduce stress as much as possible. Look at all the areas in your life and if there is anything that negatively impacts you cut it out! “


It can also encourage more synthesis of T4 into RT3. When our body produces too much T4 and cortisol the liver over-compensates, trying to desperately manage it by turning it into RT3.

Low ferritin 

Ferritin is a form of stored iron. Low levels of stored iron is a common reason for hair loss. Women who suffer from hypothyroidism tend to also suffer from low ferritin. The two conditions often go hand in hand. If you’re experiencing hair loss, ask your doctor to check your iron and ensure that it includes a test for ferritin. This is because your iron levels can appear ‘normal’ even though your ferritin levels are low and that could be the logic behind your hair loss. ‘Normal’ doesn’t necessarily mean ‘optimal’!

Ferritin is used during the growth stage of our hair (the anagen phase). It helps fuel this important stage of your hair’s development and encourages it to grow to its full length. If your diet lacks the iron that your body needs, it automatically pulls it from non-critical areas of the body, such as hair bulbs. In other words, it prioritises organs like your heart, over hair growth. This exchange of resources is very likely to lead to some form of hair loss.

Your doctor should be able to give you a printout of your test results, but how do you interpret what you read? On average, ferritin levels tend to lie between 14 and 170 ug/L. Ideally, it should be around 80 ug/L for healthy hair follicles.

Unstable blood sugar and insulin resistance 

Blood sugar imbalances can affect your health in a variety of ways, including hair loss problems.

When it’s out of balance, levels in the blood can either be too high (hyperglycaemia) or too low (hypoglycaemia).


I hope you liked this article about the thyroid gland terms and functions. If you would like to learn more about my tips and tricks on how I saved my life from being chronically ill and tired to the lively person I am today, ensure to check out other pages of this anti-ageing wellness platform.




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