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  • Writer's pictureCheryl Penna

Cause of Low Thyroid Function

The Thyroid Gland is one of the largest hormone producing glands in the body. It manufactures two hormones know as triiodothyronine (T3) and tetraiodothyronine (T4).

Thyroid hormones are responsible for controlling the basic activity of each cell in the body, including metabolism, growth and development, temperature regulation, heart rate and production of proteins used by the cells every day.

If thyroid hormones (T4 & T3) are low, metabolism inside the cells slows down and energy levels drop. This can be the first sign of hypo functioning of the gland that can continue for weeks or months before causing people to seek advice from their medical practitioner.

Known as Hypothyroidism, this is where we you see a raised TSH (Thyroid Stimulating Hormone), a low T4 and low T3 level on pathology test results. This indicates that the thyroid gland is struggling to produce enough thyroid stimulating hormone that is needed to produce T4 (storage hormone) and T3 (active hormone), that is converted from T4 production via the liver and other cells in the body.

This is a pattern that I often see in many of my patients and whilst some respond well to medication, this is not the driving cause of the hypo-functioning of the gland.

There are many nutritional factors involved with the production of thyroid hormones. The three basic ones are low iron, low iodine and low tyrosine that are needed in our diet to support adequate thyroid hormone production.

Hashimoto's thyroiditis is also associated with hypo-functioning of the gland but in this instance, we see a raised level of thyroid auto-antibodies due to an overactive immune system response that mis-identifies the tissues in the gland, causing white blood cells to attack the thyroid gland, causing inflammation and tissue damage.

This condition needs to be treated very differently from the hypo-functional condition that focuses on calming down the overactive immune system and identifying the reaction that caused the immune response.

Symptoms of low thyroid function include fatigue that lasts all day and is not resolved with time off or good sleep. It can also cause dryness in the skin, constipation, brain fog, cold sensitivity, and in some, abdominal weight gain.

What about other hormones?

The interaction between sex hormones and thyroid hormones is also significant. Elevated oestrogen levels can block the effect of thyroid hormones increasing the development of hypothyroidism.

The female hormone oestrogen can stimulate the production of a protein, which binds to thyroxine (T4) and inactivate activity. Correcting underlying oestrogen excess is essential in addressing an under active thyroid problem.

In addressing oestrogen excess, we also must assess gut and liver function that are the prime organs for oestrogen clearance.

What about Stress?

Excess cortisol production from long-term stress can also have negative impacts on thyroid health. Specifically, when the body is stressed, it becomes clever and makes a mirror image of T3, called reverse T3 (RT3).

RT3 is the body's shut down signal, it says to the body there are not enough resources to sustain all biological functions of the body so non-essential functions such as fat metabolism, reproductive function and energy production must be shut down to reserve resources for essential functions to keep the body alive. This is believed to be an inbuilt system of survival that has developed over time.

How to Assess Thyroid Function?

The first step in assessing thyroid function is to get a full set of pathology tests done with your practitioner as well as a full health system overview.

Additionally, I recommend testing iron levels, AM cortisol, full hormone panel if indicated, liver function, full cholesterol panel and any other markers that are indicated at your consultation.

Unfortunately, many of our patients have only had their GP assess their TSH as a baseline marker and as you can see, this gives up very little information to assess and correct under active function of the gland and its cause.

I-Screen Pathology

We are currently using i-screen pathology to enable us to get a full assessment of the thyroid, hormones, iron and insulin levels for $189.00. If this is something that interests you, please contact reception for more information. **Price correct as of May 2022**

Nutritional Support for the Thyroid Gland

From a nutritional perspective, there are some key nutrients and dietary practices which help to support under active / sluggish thyroid:

Iron is a co-factor for iodination of tyrosine and iron deficiency blunts thyroid responsiveness to iodine repletion. Food sources of iron include red meat, almonds, apricots, organic liver, sunflower, and pumpkin seeds.

Goitrogens (especially if iodine deficient) found in raw broccoli, kale, cabbage, and cauliflower as well as bromide (often used in flour), fluoride (unfiltered water) and chloride can also interfere with iodine . Cooking these foods will reduce the goitrogens, using filtered water and avoiding foods such as commercial bread and flour will reduce your exposure to these thyroid blocking chemicals.

Zinc and selenium are both co-factors for the conversion of T4 to T3 so very important. Food sources of zinc include beef, egg, capsicum, pumpkin seeds, and food sources of selenium include Brazil nuts, barley, cashews, peanuts, tuna, and cooked broccoli.

Sufficient iodine levels are needed and can be assessed in clinic using our Oligoscan device or via a Urinary Spot Test. Food sources of iodine include asparagus, cod, dairy, seaweed, and oysters.

Tyrosine is an important amino acid needed to make thyroxin hormone. Sources include almonds, avocado, banana, beef, cheese, chicken, eggs, fish, and most protein powders contain an essential range of amino acids that include tyrosine.

Dietary and Lifestyle factors that Impact Thyroid function

Intermittent fasting and low carbohydrate intake have been shown to induce hyper functioning of the thyroid.

When we see a low T3 production on a pathology test, this indicates inadequate carbohydrate intake may be the driver of low T3 production.

This is where I recommend for regular intake of complex, fibre rich carbs including brown rice, root veggies, quinoa, and legumes with adequate protein and healthy fats to support blood sugar levels and energy production.

It is essential to reduce inflammatory foods that are a driver of inflammation that needs to be addressed in both hypo function and autoimmune Hashimoto's thyroid. These foods include deli meats, refined sugar, refined oils and processed gluten and dairy in diet.


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