What does a Low Functioning Thyroid (Hypothyroidism) mean?

Tired and fatigued? Always feeling cold? Hair falling out and dry skin? Weight gain? Foggy brain? These can be signs of an under-active thyroid. What does this mean? 

What is the Thyroid?

The thyroid is a butterfly shaped gland found surrounding the windpipe on 3 sides in the lower neck. 

It is responsible for making Thyroxin (T3), which is important for the functioning of all cells.

This hormone is a stimulatory hormone and is responsible for such things as energy levels, cognition, brain (1), tissue regeneration, bone formation (2), normal digestion, and emotional stability (3).

When the thyroid is under active (hypothyroidism) it causes symptoms (4) such as fatigue, Increased cold sensitivity, Dry skin, puffy face, weight gain (5), constipation, muscle weakness, increased cholesterol levels (6,7), hoarseness, thinning hair, stiffness, pain or swelling of joints, Depression, heavy or irregular menses, impaired memory and a slow heart rate. The gland may be swollen which is known as a goiter (3).

When you get your thyroid tests, acronyms such as TSH, T3, T4 and rT3 are thrown around. There may also be words such as autoimmune, antibodies, nutritional status used. These can be quiet confusing.

Here are some things to provide some clarity (3):    

1. As in all things the brain is the master controller. It tells the hypothalamus in the brain to produce TRH (thyroid release hormone), which stimulates a little gland at it’s base called the pituitary gland to produce a Hormone called TSH otherwise known as Thyroid Stimulating Hormone.    
2. Just as its name implies, it “talks” to the thyroid to stimulate it to produce a hormone T4, which is the inactive form of thyroxin. The 4 in T4 refers to the 4 iodine atoms that it has (8).
3.  This is then converted to T3, which is the active form of thyroxin and contains 3 iodine atoms.
4. The T3 is then used by the cells (9) in their functioning (previously discussed).

When there is too much T3/T4 the brain is singled to decrease its production of TSH, which will intern decrease the formation of T4 T3.

If there is too little T3 and T4 the brain is signaled to increase its production of TSH normally resulting in an increase in T3 and T4.

However if there is malfunction (3) we may get the low T4 and T3 signaling the brain to produce more TSH but no more T4 and or T3 is produced. This causes increased levels of TSH but still low T4 and/or T3. This lower level of T3 would result in Hypothyroidism.

At this time we need to bring in a little thing called Reverse T3 (rT3) (3). This is an alternative product produced instead of T3 from T4 (10). When this happens the low levels of T3 tells the brain to produce more TSH, which tells the thyroid to produce more T4 only this is not resulting in more T3, but rather rT3. This is not only inactive, but also blocks the T3 at cellular level. The result is elevated levels of TSH, normal to elevated levels of T4, elevated levels of rT3 and low levels of T3 resulting in hypothyroid symptoms (3).

There are a number of causes of hypothyroidism:

Nutrient deficiency (3), namely Iodine (8,11), Selenium, Tyrosine, Zn B vitamins, folate, vitamin A and C. Selenium is used for the conversion of T4 to T3. If deficient it can result in rT3.

Autoimmune problems (3,11,12), which is when the body produces antibodies against the thyroid and its production of T3. This is effectively the body fighting against itself.

High levels of cortisol produced by stress. This results in high levels of rT3 (3).

Pathology testing:

As can be seen there are many complicating factors which, can result in this condition not being correctly diagnosed (13). 

For this reason, when testing for thyroid issues I like to have a full profile done of TSH, T4, T3, rT3 and Antibodies. 

Additionally, depending on the individual and the above results I may also request Iodine status and cortisol levels. 

This provides a better picture allowing us to be more directed in our treatment of the problem (14).

I hope this has provided a better insight to the Thyroid and how it is impacted by diet and nutrients, autoimmune conditions and stress. 

Coming Soon:

Please look out for my article on the Stress and Adrenals 

Reference:

1.         Howdeshell KL. A Model of the Development of the Brain as a Construct of the Thyroid System Developing a Timeline Model of Thyroid System and Brain. Environ Heal. 2002;110:337–48.

2.         Gogakos AI, Duncan Bassett JH, Williams GR. Thyroid and bone. Arch Biochem Biophys. 2010;503(1):129–36.

3.         Gruner T. Thyroid abnormalities. In: Sarris J, Wardle J, editors. Clinical Naturopathy 2e - An evidence-based guide to practice. 2e ed. Sydney: Elsevier Churchill Livingstone; 2014. p. 399–417.

4.         Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado thyroid disease prevalence study. Arch Intern Med [Internet]. 2000;160(4):526–34. Available from: http://www.ncbi.nlm.nih.gov/pubmed/10695693\nhttp://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=10695693&retmode=ref&cmd=prlinks

5.         Laurberg P, Knudsen N, Andersen S, Carlé A, Pedersen IB, Karmisholt J. Thyroid Function and Obesity. Eur Thyroid J [Internet]. 2012;1(3):159–67. Available from: http://www.karger.com/doi/10.1159/000342994

6.         Lu M, Yang CB, Gao L, Zhao JJ. Mechanism of subclinical hypothyroidism accelerating endothelial dysfunction (Review). Exp Ther Med. 2015;9(1):3–10.

7.         Tognini S, Pasqualetti G, Calsolaro V, Polini a, Caraccio N, Monzani F. Cardiovascular risk and quality of life in elderly people with mild thyroid hormone deficiency. Front Endocrinol (Lausanne) [Internet]. 2014;5(October):153. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25339939\nhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC4188129/pdf/fendo-05-00153.pdf

8.         Pesce L, Kopp P. - Iodide transport: implications for health and disease. Int J Pediatr Endocrinol. 2014;1(8):1687–9856.

9.         Hennemann G, Docter R, Friesema ECH, Jong MDE, Krenning EP, Visser TJ, et al. Plasma Membrane Transport of Thyroid Hormones and. Endocr Rev. 2006;22(4):451–76.

10.       Reverse T3 , or rT3 - Understanding The Role This Thyroid Hormone Plays In Hypothyroidism [Internet]. 2016 [cited 2016 May 25]. p. 1–39. Available from: www.holistic-hypothyroidism-solutions.com/reverse-t3.html

11.       Ergür AT, Evliyaoǧlu O, Şiklar Z, Bilir P, Öcal G, Berberoǧlu M. Evaluation of thyroid functions with respect to iodine status and TRH test in chronic autoimmune thyroiditis. JCRPE J Clin Res Pediatr Endocrinol. 2011;3(1):18–21.

12.       Autoimmunity IT. Induces Il-8 Production : a New Mechanism for Hcv. 2009;31(4):339–44.

13.       Kek PC, Ho SC, Khoo DH. Subclinical Thyroid Disease (2).pdf. 2003;44(11):595–600.

14.       Collins J. Phytotherapeutic Support of Thyroid Function. 2007;(January).