Thyroid Function

May 23, 2022

The thyroid is a butterfly-shaped gland located in front of your throat, below the thyroid cartilage that is sometimes called the ‘Adam’s Apple.’ It has two lobes that lie one on either side of the windpipe. It releases hormones that modulate metabolism.

The thyroid releases three main hormones:

Thyroxine or inactive T4
Triiodothyronine or active T3
Calcitonin – regulates the level of calcium in your blood

Thyroid hormones regulate many vital functions in the body including:

Breathing
Heart rate
Central and peripheral nervous systems
Body weight
Menstrual cycles
Cholesterol levels
Body temperature
And more

You could think of the thyroid as a key component of an engine, if this component is not functioning well, it causes the engine to malfunction. Every single cell in your body has a receptor on its surface for thyroid hormones to act upon. This means that how your thyroid function impacts the function of every major system in the body.

Below are some factors that can impact healthy thyroid function.

The Thyroid-Stress connection

Healthy thyroid function is dependent on healthy adrenal glands. The adrenals are two small glands that sit on top of the kidneys. These glands secrete several hormones, including our stress hormones and they regulate our stress response. Stress can be defined as anything that disturbs the body’s natural balance, this can include physiological and psychological stressors.

Most of us are aware of obvious sources of stress such as relationship challenges, financial hardship or burning the candle at both ends. There are also less obvious forms of stress that will affect the function of our adrenal glands, these can include gut dysfunction, blood sugar imbalances, food intolerances, environmental toxins, or inflammation. Any of these stressors will cause the adrenals to produce higher levels of stress hormones such as cortisol.

Higher stress levels will suppress thyroid function by interfering with the communication between the thyroid gland and the brain

Stress can cause suppression of our immune system, leading to disruption of the autoregulation of the immune system. This may lead to autoimmune thyroid conditions such as Hashimoto’s and Graves’s disease.

Stress interrupts the conversion of the inactive T4 to the active T3, instead of redirecting T4 conversion to Reverse T3 which is a highly inactive thyroid hormone.

Chronic stress impairs the liver’s ability to detoxify excess hormones via the methylation cycle. Hormones such as oestrogen then recirculate causing high levels. These high levels increase a hormone-binding protein that prevents the active T3 from circulating and acting throughout the body.

The Calorie-Thyroid Connection

Undereating or calorie restriction can significantly suppress thyroid function. When our brains determine there are too few calories available, it elicits a physiological survival response which tells the thyroid to reduce the production of thyroid hormones so as to slow the metabolism.

If you are restricting calories and are experiencing any of the following signs/symptoms, it may indicate that your thyroid function has been impacted –

Low energy/fatigue
Poor sleep
Feeling cold or experiencing cold hands and feet
Hair loss
Constipation
Brain fog
Low mood
Low blood pressure

When you consume a healthy number of calories for your needs, you are reducing the stress response and the body responds with healthy thyroid function.

The Thyroid-Gut Connection

The gut is our ‘seat of health.’ When we have poor gut health it can disrupt many of our body systems. The gut and the thyroid have a strong connection, poor gut health can lead to thyroid dysfunction and suppressed thyroid function can lead to poor digestive function and gut dysbiosis.

The gut lining acts as a barrier between us and the outside world. It protects us from any pathogens we may take in with food from finding its way into our bloodstream and causing an immune response.

A dysbiotic gut can lead to hyperpermeability (‘leaky gut’). This hyperpermeability is the opening of tight junctions, allowing large particles and pathogens to move through the gut barrier and cause havoc. These molecules are not supposed to leave the gut so the immune system will mount a response. If the immune system is continually activated (such as every time food from the gut moves through the open gap junctions) it can become hyperstimulated and this is how there can be the potential for autoimmune conditions such as autoimmune thyroid conditions to develop.

Some other examples of the gut-thyroid connection include:

We need healthy gut bacteria to convert the inactive T4 into the active T3
Poor gut health can lead to slow transit time or constipation, resulting in recirculation of hormones and toxins, both of which will cause a suppression of thyroid function
Low thyroid function can cause constipation, which impacts gut health.
Inflammation within the gut causes a stress response and increase in cortisol, reducing the active T3 production and increasing the inactive reverse T3 production.
Low thyroid hormone production impacts bile release into the small intestine, causing constipation and an increased risk of SIBO (Small intestinal bacterial overgrowth).

These are just a few examples of factors that can affect our thyroid function. As with all health issues we support in holistic functional medicine, getting to the root cause of the dis-ease in the body is important. In the case of thyroid dysfunction, we can see from the above that if we only addressed the thyroid, the outcomes could be potentially unsuccessful as the underlying cause would continue to drive the imbalance.

Would you like to get a full workup of your profile beyond the standard markers, or discover underlying drivers of your thyroid imbalance?