It’s not you, it’s your THYROID. The Science Behind Your Thyroid

by Dr. Samina Mitha, ND

Does this sound familiar?:

  • You are always the cold one, while everyone around you is fine?
  • You have been successful at losing weight, but the pounds aren’t coming off anymore?
  • Your hair and nails have become brittle?
  • You seem to always forget where you put your keys?
  • You’ve been constipated ever since you can remember?
  • You are so tired that you are dragging body everywhere?

These are some of the most common thyroid symptoms we see along with: Dark circles/puffy eyes, hoarseness of the voice, dry skin, lack of energy, anxiety, thinning hair and insomnia.

Today I want to talk about a conversation I have with many of my patients – the science behind the thyroid…

In our brain the hypothalamus releases thyroid releasing hormone this signals to the pituitary gland in the brain to release – thyroid stimulating hormone AKA TSH. This signals to our thyroid to release T4 (Thyroxine). T3 (Triiodothyronine) is our more active thyroid hormone since it is 4 times more potent than T4. Majority of T3 is made from the conversion of T4 to T3. It plays a part in almost every single cell in our bodies to regulate metabolism. Metabolism is our ability to convert oxygen and calories into energy. Thyroid hormones also help with growth and development, body temperature, heart rate, energy, helps with protein synthesis and can increase serotonin in our brain (our happy hormone).

When your body is producing T3 and T4 at strong levels it will signal to the brain that the body doesn’t need any more TSH. But when the body isn’t producing enough T3 and T4, the body will signal the brain to release more TSH. This is when we see high levels of TSH on blood reports suggesting something called hypothyroidism.Thyroid Pathway

Typically hypothyroidism is treated with Synthroid which is a synthetic form of T4 hormone. However, knowing that T3 plays majority of the role in carrying out the functions of the thyroid, in order for the medication to be successful you need to be converting the T4 into T3. This is why we see patients on thyroid medication with unmanaged symptoms.

Sometimes T4 can be converted into reverse T3. This is known as the inactive form of thyroid hormone. Reverse T3 can become elevated in the following scenarios:

  • Stress
  • Insulin resistance/diabetes/metabolic syndrome

Some things that may prevent the body from converting T4 to T3 include:

  • Stress
  • Lack of minerals such as iodine/selenium
  • Improper gut bacteria
  • Inflammation of the gut
  • Exposure to toxins such as BPA, pesticides, mercury and flame retardants


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