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The thyroid…. What is its job, what can go wrong and why test it?

Updated: Jan 4, 2022

What does the thyroid do? The thyroid, which is a part of the endocrine system, is located below your Adam's apple and is a butterfly-shaped powerhouse that is responsible for the bodies metabolism. It produces a hormone called thyroxine (T4). This is then converted by an enzyme to the active form, triiodothyronine, (T3) which is used by the bodies cells (1,2). The hypothalamus and pituitary glands will then control the amount of thyroid hormone that is produced daily. They monitor the number of thyroid hormones circulating in the body and tell the thyroid gland when more thyroid-stimulating hormone (TSH) is needed (1). Clever right?

This tiny, yet very important gland produces hormones that are crucial in maintaining your metabolism and aiding the regulation of other hormonal systems in the body.

What happens when there is an imbalance? Many factors can be at play when dysfunction in the thyroid occurs, but when they do you can get:

  • Hashimoto, which is a form of autoimmune hypothyroidism. This occurs when the body mistakenly attacks the thyroid gland, leading to the thyroid not making enough hormones. This is very common in women (5).

  • Hypothyroidism or low thyroid is when the thyroid gland is not producing and secreting enough T4 hormone into the body. This is a very common condition in women, the elderly and those with an autoimmune disorder (7).

  • Hyperthyroidism is when the thyroid gland produces too many thyroid hormones - common in women during pregnancy, menopause and the over 50s (2,6).

Now let's talk about testing

So why is this not giving us a full picture? and what does the thyroid panel testing show?

If you suffer from the common symptoms of a thyroid problem, your GP will normally perform a blood test showing the levels of TSH and sometimes will test T4 levels. If the levels are too imbalanced, high or low, a diagnosis is given, alongside medication. These tests will aid the diagnosis of a thyroid imbalance along with the symptoms, yes, but these also do not measure the thyroid autoantibodies, which are associated with autoimmune thyroid conditions like Hashimoto's and reverse T3, which prevents the active hormone T3, getting to cells where it needs to be (1).

What these private tests show is that you can have “normal” levels of the thyroid markers, T4 and TSH but have abnormal Reverse T3 levels. If these are high, then the metabolic rate of the body dips and symptoms like fatigue and weight gain show (8). Thyroid markers can also be shown as normal, yet you could have low levels of T3 (the active thyroid hormone) or elevated autoantibodies which have a similar effect to hypothyroid conditions.(1)

So, if you are being told your thyroid levels are in the normal range, yet are still experiencing symptoms such as the ones shown in the chart, then it may be worth speaking to a trained Nutritional Therapist or Nutritionist. They can help get a private test and support the findings. Companies such as Genova Diagnostics and Regnerus, range between £99-£188, with additional consultations needed for interpretation (8) . Here are a few nutritional tips on supporting the most common form of thyroid disorder,

Hypothyroidism: FOODS rich in iodine, selenium, iron and essential vitamins 🥚 Eggs = Iodine and Selenium. 🥩 Meats = Selenium. All meats include chicken, lamb, turkey, beef. 🍣 Fish = Iron and omega 3 fatty acid and vitamin D, which are just good all round. All types of seafood. 🥒 Vegetables. All as they are full of essential vitamins and minerals. Mushrooms have good levels of selenium. Seaweed is one of the best natural sources of iodine. BUT, avoid eating raw cruciferous veg though, ensure they’re lightly steamed (cruciferous veg = arugula, bok choy, broccoli, Brussels sprouts, cabbage, cauliflower, collard greens). 🍏 Fruits = Essential vitamins and minerals. Bananas are higher in selenium than other fruit. 🍚 Grains = Iron, zinc and B vitamins. Rice, spelt, quinoa, oats 🥜 Nut and seeds = Selenium, zinc. Chia seeds, sunflower and pumpkin seeds, flax seeds, peanuts and brazil nuts. 💊 Supplement support can be very effective, I love the BioCare thyroid complex ( but the diet should always be considered first (1,2,3). I hope this has made the magical world of the thyroid a little less daunting and confusing, next week I will be chatting about thyroid and pregnancy and why it is becoming common to see a thyroid condition develop during or after pregnancy.


1. Beirne A, Nicolle L. Biochemical imbalances in disease.

2. Walker A. Case studies in personalized nutrition.

3. Murray M, Pizzorno J, Pizzorno L. The encyclopaedia of healing foods. London: Piatkus; 2008.

4. Schmidt R, LoPresti J, McDermott M, Zick S, Straseski J. Does Reverse Triiodothyronine Testing Have Clinical Utility? An Analysis of Practice Variation Based on Order Data from a National Reference Laboratory. Thyroid. 2018;28(7):842-848.

5. Caturegli P, De Remigis A, Rose N. Hashimoto thyroiditis: Clinical and diagnostic criteria. Autoimmunity Reviews. 2014;13(4-5):391-397.

6. Johnson J, Felicetta J. Hyperthyroidism: A Comprehensive Review. Journal of the American Academy of Nurse Practitioners. 1992;4(1):8-14.

7. Biondi B, Cooper D. Thyroid hormone therapy for hypothyroidism. Endocrine. 2019;66(1):18-26.

8. Thyroid Test | Comprehensive Thyroid Assessment [Internet]. 2022 [cited 4 January 2022]. Available from:


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