Could You Have an Underactive Thyroid?

The thyroid is a butterfly-shaped gland in your neck, which controls your metabolism. Your thyroid is inter-related with every system in your body, so if your thyroid is not working to its optimum, then neither are you.

Hypothyroidism, or an under-active thyroid, accounts for 90% of all thyroid imbalances and is a common medical condition, particularly in women over the age of 40 years. UK prevalence for clinical hypothyroidism is 9.3% in women and 1.3% in men; however, many more fall into the ‘sub-clinical’ category, completely unaware that their low thyroid function could be resulting in a general feeling of being ‘not quite right’.

Common Signs of an Underactive Thyroid

  1. Fatigue / low energy despite sleeping 8 to 10 hours a night

  2. Steady weight gain or the problems trying to lose weight

  3. Mood swings, anxiety, or depression

  4. Brain fog, poor concentration, or poor memory

  5. Hormone imbalances - PMS, irregular periods, infertility, low sex drive

  6. Muscle and/or joint pain

  7. Cold hands and feet

  8. Dry or cracking skin, brittle nails

  9. Hair loss

  10. Constipation

So How Does the Thyroid Actually Work?

Thyroid hormone production is regulated by a feedback loop mechanism between the hypothalamus, pituitary gland, and the thyroid gland. Thyroid Stimulating Hormone (TSH) stimulates production and the release of hormones T4 and T3 from the thyroid gland. When enough T4 is produced, it signals that there is enough thyroid hormone in circulation, causing production to cease. About 85% of the hormone produced by our thyroid gland is T4, which is an inactive form of the hormone. After T4 is made, a small amount of it is converted into T3, which is the active form of thyroid hormone. To complicate matters, T3 also gets converted into either Free T3 (FT3) or Reverse T3 (rT3). It is the Free T3 that really matters in all of this, since it’s the only hormone that can attach to a receptor and cause our metabolism to rise, keeping us warm, our bowels moving, mind working, and other hormones in check. The role of rT3 is not well known, however, it is usually elevated in persons under extreme stress and those who have mercury toxicity.

Hashimoto’s thyroiditis, an autoimmune disease, is the most common form of hypothyroidism. An autoimmune disease is one in which your body turns on itself and begins to attack a certain organ or tissue believing its foreign. When testing thyroid function it should include screening for Thyroid Peroxidase Antibodies (TPOAb) and Thyroglobulin Antibodies (TgAb), which would indicate autoimmune disease.


GP’s usually test for TSH and T4, it is unlikely they check FT3, RT3, or thyroid antibodies levels. They also compare results to the ‘normal’ lab reference range, for which there is much debate and does not highlight sub-optimal levels. To check the full function of the thyroid gland the following levels should be tested:

  • Thyroid Stimulating Hormone (TSH)

  • Free T4 (FT4)

  • Free T3 (FT3)

  • Reverse T3 (RT3)

  • Thyroid Peroxidase Antibodies (TPOAb)

  • Thyroglobulin Antibodies (TgAb)

How to Support Low Thyroid Function

If your tests show that you have a low functioning thyroid, you may need medication and your GP will advise on this. There are also a number of changes you can make with regards to nutrition and lifestyle to support it. However, I would recommend seeing a registered nutritional therapist, as an individual approach based on your specific test results would be most beneficial.

  1. Gut health - Make sure your digestive system is functioning properly; this is critical to good health.

  2. Supplement a high quality multivitamin that contains iodine, zinc, selenium, iron, vitamin D and B vitamins.

  3. Supplement tyrosine and iodine (to help with the FT4 to FT3 conversion).

  4. Go gluten-free - essential if you have Hashimoto’s.

  5. Manage stress levels and support adrenals - the adrenal glands and thyroid work together so if the body is under stress it will have a detrimental affect your thyroid function. Indeed, adrenal fatigue can manifest in symptoms of low thyroid function, so if thyroid results come back normal, check your adrenal function.

  6. Rest - get a minimum of 8 hours of sleep a night.

  7. Remove toxins - amalgam fillings and fluoride, bromide, and chlorine from your diet and environment.

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