Thyroid 101: The Ins & Outs of Thyroid Function

Recent studies suggest that 1 in 10 Canadians suffer from some kind of thyroid disease, of which 50% are undiagnosed! One in eight women will develop a thyroid disorder in her lifetime, with the number of affected people continuing to rise each year. Until this gland goes awry, very little attention is given to its small, butterfly shaped presence at the base of the neck – yet the hormones it secretes are essential to all growth and metabolism.

Every cell in the body has receptors for thyroid hormone – that means that every cell is affected when there is inadequate thyroid hormone circulating. Every aspect of body function and every organ system is affected – neurological function, digestion, circulation, bone metabolism, immune function, gallbladder and liver function, hormone production, glucose metabolism, lipid and cholesterol metabolism, protein metabolism and body temperature regulation. That is just for starters.

You can think of the thyroid as the central gear in a sophisticated engine. If that gear breaks, the entire engine goes down with it. Not only is it absolutely necessary for the engine to function, it also dictates the rate at which every biochemical reaction takes place in the body. If the food you eat is the fuel, thyroid hormone is the fire that burns it.

The thyroid gland releases primarily Thyroxine (T4) but does release a small amount of Triiodothyronine (T3). T4 has minimal physiologic effect and is converted to the much more metabolically active T3. The hypothalamus, located in the brain, detects the amount of T4 circulating in the body and increases or decreases the amount of Thyroid Releasing Hormone (TRH) that is sent to the pituitary gland. The pituitary gland responds to the amount of TRH by releasing more or less Thyroid Stimulating Hormone (TSH).

When T4 levels are detected as low, the pituitary sends more TSH to the thyroid to try to increase the amount of T4 released. Conversely, when T4 is elevated, the pituitary reduces the TSH release so that T4 release will also decrease. Therefore, the brain & pituitary gland are critical to the regulation of T4.

Thyroid hormone released from the thyroid is transported on proteins in the blood. Most of this is Thyroid Binding Globulin (TBG). Hormones attached to proteins in the blood are in a constant state of flux meaning that they are constantly attaching and detaching. This is a good thing since only free hormone (unattached) is available for biologic activity. Therefore, the greater the quantity of TBG the less hormone is free. This means that increased levels of TBG can result in hypothyroid symptoms since less free hormone is able to interact with the thyroid receptors.

As stated above, T4 has minimal metabolic activity and must be converted to T3. T3 binds to its receptor and exerts its metabolic effects. T4 has to be converted. The process of this conversion is imperfect and T4 can be converted to either T3 or Reverse T3 (RT3). The problem here is that RT3 is not only ineffective but also blocks the T3 receptor and prevents T3 from having its effect.

Patterns of Thyroid Dysfunction:

There are several ‘patterns’ of thyroid dysfunction. Unfortunately, most of the time, despite the cause of dysfunction, the standard treatment is to offer a prescription of synthetic T4 (Synthroid). Optimal treatment would include addressing the cause – whether it be an issue of environmental toxicity, nutritional deficiency, hormonal imbalance or improper immune function – to restore optimal thyroid production, without the lifelong dependence on thyroid hormone replacement.

Primary Hypothyroidism:

This is a problem of the thyroid gland simply not producing enough T4. In this circumstance, a prescription of Synthroid is the most appropriate treatment short term until the root cause for T4 underproduction is addressed.

Hypothyroidism is one of the most common thyroid disorders, with up to 10% of women over 60 having clinical or subclinical hypothyroidism. Symptoms include: slow mental/cognitive function, depression, easy weight gain, constipation, dry skin, hair loss, cold intolerance, irregular menstruation, elevated cholesterol, infertility, muscle stiffness and pain, and compromised immune function.

The most common cause of Primary Hypothyroidism is Hashimoto’s Thyroiditis. This is an autoimmune condition where the body attacks itself causing decreased T4 release. The very first thing to do is to change to a completely gluten-free diet. Once there is one autoimmune disease, the likelihood of developing another autoimmune condition is one in three, so it is important to correct the causes leading to the auto-immunity, under the guidance of a qualified healthcare practitioner, to prevent the development of further chronic disease.

Hypopituitary Hypothyroidism:

The pituitary isn’t working right for any number of reasons and isn’t sending TSH to stimulate the thyroid gland. This is often associated with adrenal issues from chronic stress and fatigue.

Thyroid Underconversion:

T4 has to be converted to T3 but the process is disrupted for any number of reasons (see below).

Thyroid Overconversion & Decreased TBG:

Elevated testosterone causes an increase in T4-T3 conversion. It also decreases TBG levels. This results in excess Free T3 stimulating the cells. Over time, this results in a resistance to T3 and hypothyroid symptoms due to this resistance.

Elevated TBG:

Increased estrogens cause an elevation of TBG. The more TBG, the less free hormone. The less free hormone, the less effect. Therefore, increased TBG causes hypothyroid symptoms. The treatment is centered around normalizing estrogen levels.

Thyroid Resistance:

Thyroid resistance occurs when the all of the appropriate labs have been obtained but the levels are normal. However, the patient STILL has the symptoms of hypothyroidism. Typically, this is due to increased stress which elevates cortisol levels. Elevated cortisol can make the cells resistant to the thyroid hormones.

More on thyroid conversion:

There are numerous factors that can alter the conversion of T4 to T3.

List of things that can cause problems with T4-T3 conversion:

The problem with conversion of T4 to RT3 is twofold. First, it consumes too much of the T4 and makes a substance that has no thyroid effect (RT3). Second, the RT3 blocks the thyroid receptor as previously stated.

Since the problem here is that we are making too much RT3 from T4, giving more T4 can actually make the problem worse! I usually recommend stopping all T4 supplementation (including Armour thyroid) and then start working on why RT3 is being over produced.

There may be a problem with TSH &/or T4 on labs but they may be normal. You have have symptoms of thyroid problems and go to your doctor to have a ‘thyroid’ test performed. If your TSH is high, you will undoubtedly be started on Synthroid or equivalent. You may even have your labs return to normal but we certainly haven’t ‘fixed’ the problem!

That means you probably won’t feel normal!

Remember, the key to addressing the problem is to identify the problem and customize the treatment for each patient based on what is wrong.

Synthetic T4 is an appropriate medication in some cases, no question. My experience has been that thyroid problems have been inadequately worked up and so the appropriate diagnosis cannot be made. Without an accurate diagnosis, the correct treatment cannot be instituted. Without correct treatment you will probably never feel normal.

I hope this information helps you to understand the issues with the thyroid gland and HOW it can malfunction. If you feel like you need help with healing your thyroid, then please contact us, and let’s get started!

References:

1. http://www.altsupportthyroid.org/t3/t3medrefs2.php
2. http://en.wikipedia.org/wiki/Thyroid_hormone
3. http://en.wikipedia.org/wiki/Hypothalamic%E2%80%93pituitary%E2%80%93thyroid_axis
4. http://www.lowcarbfriends.com/bbs/thyroid/657835-things-inhibit-t4-t3-conversion-some-useful-thyroid-tips.html
5. http://www.stopthethyroidmadness.com/
6. http://www.thyroidbook.com/
7. http://www.apothecarytulsa.com/thyroid_hormones.asp
8. http://www.ncbi.nlm.nih.gov/pubmed/11929079?dopt=Abstract
9. http://www.ncbi.nlm.nih.gov/pubmed/9971866?dopt=Abstract