In this weeks article I wanted to start writing the first part in a series on the thyroid & go on in future parts to explain the connection to other areas of the endocrine system such as its relationship with the adrenal glands, other hormones & the rest of systems biology from a Functional Medicine Clinician’s perspective & over a decade of clinical experience.
The thyroid gland is one of the family of glands collectively called the endocrine system. Endocrines secrete within themselves complex molecules called hormones (from the Greek “hormon” meaning to stir up, which is just what they do). These hormones pass into the bloodstream, where they act as chemical messengers, targeting other glands or organs or tissues, and telling them what to do. Vital functions of the body are controlled in this way, the endocrine glands responding to the needs of the moment. (To avoid confusion, the other group of hormones, called exocrine glands, passed their secretions straight to the sight of action as for example, the salivary glands.)
If you have a glance at the infographic below you will see where these very special glands are situated and the hormones that they are responsible for secreting. Working from the top downwards, the first is a pea-sized pineal gland. This is deep within our brains covered by the cerebral cortex. The interesting thing is that in primitive animals, like certain reptiles, it’s actually so near the top of the skull that it can respond to light. Eastern mystics, even now, refer to it as the third eye. In us humans, they can still respond to light but by the way of the optic nerves which pass very close to it.
The pineal gland produces mostly the hormone melatonin and has some influence over the hypothalamus (which comes next). It is the Glen controls are bodily circadian rhythms, both short and long term. For example, as the day wears on, and the shadows fall, it produces and secretes melatonin, which shuts down our biological mechanisms so that we can drift off to sleep. There are other rhythms: those controlling, for example, seasonal activity. In some animals, hibernation; in humans, the young man’s fancy in the spring. The longest ‘rhythm’ of all is the ageing process and the timing of when to call a halt to all our conscious trials and tribulations. I will discuss the hormone melatonin in more detail in the future part of the thyroid series as it’s a very important one.
Below the pineal gland in the floor of the brain, is the hypothalamus. This is part brain and part endocrine gland. It is the interface between our endocrine system and what is going on in the outside world, as passed to it from the input of our senses via the brain. Hence we can control to a degree, albeit largely unconsciously, at endocrine system.
To exert this control over the endocrine system as a whole, the hypothalamus wraps out its instructions to the pituitary gland attached by stalk just below it. These instructions come as ‘release’ hormones, which the pituitary must obey; and it responds by producing hormones of its own, the ‘trophic’ hormones, which are passed through the bloodstream to other endocrine glands, or tissues. The endocrine system can be like into an orchestra; with the pituitary is the conductor and the hypothalamus as the composer of the wonderful symphony of life. In the stalls sits the director, the pineal, hissing out instructions and criticism… and finally, perhaps ordering the fall of the curtain, when the functional event or performance is over.
So let us now look at the conductor, the pituitary gland if you look at the list I have prepared below you will see that it has a front (anterior) half and a back (posterior) half. The front is really quite busy, and produces many different hormones. Since these don’t all concern us at the moment, I’m not going to go into any detail about them, but I have listed them for those of you that are interested. However, two of them must catch your attention at once: the thyroid-stimulating hormone (TSH), of which a good deal more later, and the adrenocorticotrophic hormone (ACTH), which controls adrenal function. The luteinising hormone (LH) and follicle-stimulating hormone (FSH), control the female hormones and the menstrual cycle in the ladies, and the male hormones and spermatozoa formation in the lads.
- ACTH (adrenocorticotrophic hormone)
- GH (growth hormone)
- HPL (human placental lactogen)
- PL (prolactin)
- LH (luteinising hormone)
- FSH (follicle stimulating hormone)
- MSM (melanocyte stimulating hormone)
- ADH (anti-diuretic hormone) via Vasopressin
To show how all this works let’s take a look at the thyroid gland. Suppose we find that we are cold and miserable. The hypothalamus response to this by making thyrotrophin release hormones (TRH). This is now passed via the bloodstream to the pituitary gland, which then makes the TSH. And this, gets the thyroid going to produce more thyroid hormone, which increases our metabolic activity and helps warm us up.
Since I will be discussing adrenal function in a future part of this thyroid series, I can illustrate how this works in the same way. The adrenal glands can produce many different hormones, but the two we are concerned about here are adrenaline (or epinephrine in the US) and noradrenaline (norepinephrine) – the fight-or-flight (sympathetic) hormones – and cortisol, which enable the body to cope with stress; acute stress for the adrenalins, longer term stress for the cortisones is – for example, illness or severe external stress. The hypothalamus is made aware of the stress situation and produces corticotrophin releasing hormone (CRH), which stimulates the pituitary to produce ACTH and so the adrenals are instructed to produce extra cortisol.
So in essence, we have an elegant negative feedback system to control the target endocrine glands. A negative feedback is much the same as your central heating at home. As the water in your radiators gets hotter, eventually a sensor shuts off the gas. The feedback works because the hypothalamus is monitoring the blood levels of the hormones concerned as well as external inputs or signals; in the case of the thyroid hormone when blood levels are optimum the release of hormone production shutdown, and violet pituitary, the target line production is also shut down. The adrenal control is clearly the same.
There are a few people who don’t know the thyroid gland is located in the base of the neck, developing very early in fetal life. He has two lobes, which meet across the windpipe at about the level of the Adams apple, and is three or 4 inches across. Usually these lobes are not really visible, although they can be felt; but in some thyroid conditions they in large, sometimes very much, and are much easily seen. This is known as a goitre. They can also become inflamed, when they are painful to touch. Cysts & growths may from time to time occur and they too may be seen and felt. Abnormally large fibroids may be quite uncomfortable and interfere with swallowing and speech.
The function of the thyroid, in us and all mammals, is to regulate all the processes of energy released within individual cells in the body as a whole. The thyroid hormones also actors growth hormones control in tissue growth and development in early life. This is what we mean when we talk about metabolism. Metabolism is the rate at which we produce and use energy in the body. The release of energy from life processes in its simplest terms is the combination of oxygen from the air we breathe, with hydrocarbons for my food. These are molecules made up of chains of carbon and hydrogen atoms. One of the simplest is of course sugar and all the carbohydrates we are turned into the sugar glucose. by complex processes, fats and proteins can also be turned into glucose when required. All this happens within each individual cell using complex enzymes operating within a miniature energy generating Station called her mitochondrion. I’ve written about mitochondria in previous articles which you may want to revisit. Paragraph it is here the magic occurs; the carbon and hydrogen atoms are released to combine with the oxygen, forming carbon dioxide (C02) and water (H to O). This process releases chemical energy, which is what the cells live on and is known as ATP.
Never thyroid hormone works on this process into principal ways. First, assist the enzyme systems that enable these nutrients, and also electrolytes like sodium, potassium and other chemicals, to pass into the cell itself through its protective membrane. He also works in the reverse manner to allow the waste products to diffuse out. But it’s cheap importance lies in the facilitating the processes of energy production in the mitochondria cell. So any lack of thyroid hormone reduces overall energy production. Of course, too much can increase energy production above normal which is the other extreme end of the spectrum known as hyperthyroidism where the cellular engine is running too rich and burning too much fuel where it’s optimal efficiency goes out the window. These effects are readily seen and complained of by the patient.
So now we need to have a look at this magical chemical, the thyroid hormone. Actually, there are four thyroid hormones produced by the thyroid gland itself; but most of the work is done by one of them, the one called tri-iodothyronine or (T3) the biologically active form of the hormone, which I’ll go on to explain more about. The process is this… Within the colloid spaces of the thyroid – divided up into 10 or 12 compartments – the thyroid hormones are made. In the presence of the thyroid-stimulating hormone (TSH) and the thyroid peroxidase (TPO) enzyme, and the elements selenium, the ring amino acid tyrosine has one or two Eidyn atoms added to it. This is called iodination. One, or two, iodine atoms make the new compounds mono-iodotyrosine (MIT) or di-iodotyrosine (DIT). The cunning bit is that now these compounds join us, actually on top of one another. Joined up like this, they have become thyronine compounds, and may then have no I don’t atoms in the structure, or one, or two, or three, or four, depending on how many I don’t atoms were on each tyrosine ring – none, one, or two. About 80% of the thyroid output into the bloodstream is in the T4 version; about 16% as T3 and the remaining 4% made up of T2 & T1.
What is interesting, he’s had a very similar molecules are; unless you knew, you would have to look hard to see these differences, and yet they have totally different effects in the body. It all depends on how many iodine atoms there are, and where they go. So let’s have a look at them and see what they do.
First, the thyroxine or T4. Although the thyroid gland makes more of this than the others, it actually has a low biological activity and, as it stands its affect is minimal. The T4 gets attached to a protein transport compound and his world around the body in the bloodstream in temporary storage, awaiting as it were, the call of duty. In this form it is only slowly used up and has a half life of about eight days. This means that after eight days there is half the amount left; and eight further days later, half of that and so on. So if the body is not continuing to produce the correct amount, there is still some left after 4 to 6 weeks, but not very much.
As I’ve already stated, the thyroid hormone that does all the work is T3. It works like this… If we suppose that there is a need for increased energy production (say we’ve gone out into the cold without a coat I need to heat up, then the thyroid gland will soon produce more T4 and Morty three. T3 is used by the tissues for increased energy production at once; but as it gets used up, the T4 is now called upon and one of the 3 5’-deiodinase enzymes rapidly removes one of the four iodine molecules from the inactive T4 converts it to the active T3 form, which can then get to work increasing energy production (and hence ‘heat’) from the tissues – most of the conversion takes place in the liver. But what can also happen is that one of these enzymes can remove different I die and atom which then goes on to form what is known as reverse T3 (rT3), which are right about in more detail in the future part of the series. For now all I need to say is that reverse T3 has zero biological activity in the control of metabolism and can be likened to a blank rounds of ammunition and gun that makes the bang but no projectile bullet leaves the gun rendering it functionally useless.
So far as clinical medicine goes it is T3 and T4 that mostly concern us. T2 has received increasing attention from research workers of late. Previously thought to have only a role in passing, as part of the upward pathway from T1 to T3 and T4 or part of the degradation process to recycle iodine, it now seems that T2 actually has a number of important supplementary roles to play.
First of all, it has recently been found that T2 has a city military effect on the activity of the 5’-deiodinase enzyme, encouraging the the production of T3. As T3 is produced exerts an inhibitory effect on the production of TSH by the pituitary; and example of a negative feedback loop. It turns out that this inhibitory effect is much reduced where T2 is concerned, which may have metabolic advantages.
It was shown that teacher alone is effective in increasing liver metabolism and also that of heart, muscle tissue and brown adipose tissue. This is brown fat, where surplus calories are burned away rather than being deposited into fat stores. It is as good as or even better than, T3 in liver and lipid metabolism. I think that it is more than likely that he too will be shown to have a significantly greater effect than has been hitherto been thought. T2 is not prescribed by any doctors in the UK; but it is of course part of the natural desiccated thyroid supplements which I’ll go on to talk about in the future part of the series. This is perhaps why I have found they work so much better than T4 or T3 on their own.
The production of thyroid hormones, and their transport around the system in the bloodstream, all depend on a proper balance of raw materials, and enzymes controlling they use enzymes are complex substances that mediate allsorts of chemical processes; like the hormones themselves, they also require various raw materials to make them and to help the work. For the manufacture of thyroid hormones are healthy, varied and where ever possible high-quality/organic diet is beneficial. There are certain things you should eat and certain things that you should do your best to avoid or limit.
Anyone with potential thyroid issues should stay clear or limit goitregenic foods such as the brassicas, cabbage, brussel sprouts, kale etc – especially if raw or undercooked – so forget things like raw kale in smoothies as they are potentially harming thyroid function. The reason for this is that these contain thiouracil, which inhibits the actual manufacture of thyroid hormone within the gland itself. Others are, turnips, cassava, pinenuts, mustard, peanuts and millet. However, good English cooking tends to destroy these goitregens. Soya beans have high levels of phytoestrogens, which can reduce the amount of thyroid hormone available from its transport protein. Another common compound is fluoride, which is often present in conventional drinking water which has a damaging effect on thyroid manufacture and tissue uptake. Needed, or proteins which contain amino acid phenylalanine that converts to tyrosine the ‘T’ in thyroid hormone.
There also has to be sufficient iodine to join up with the tyrosine. This is represented by the number after the ‘T’ which represents the number of iodine molecules attached. Although just enough Eidyn makes the thyroid hormone actually do the work to control metabolism, too much will cause thyroid suppression. I see many people randomly supplementing with large amounts of iodine which may be doing more harm than good. The body only needs the head of a pin’s worth of iodine to carry out its functions, and everyone’s needs are highly individual and should a iodine loading test, a full thyroid panel including antibodies, as well as other functional testing should be carried out before concentrated iodine should be suggested and dosages be decided. This is not to say that a large number of people may be deficient or in need of iodine, but at the same time there are equally as many people out there that do not require therapeutic doses of supplemental highly concentrated iodine. Foods containing iodine are required in moderation: having said that, the amount of iodine depends on the iodine levels of the soil in which these particular foods are grown.
In addition to either time, there has to be enough of the metal selenium to help in the joining up process. It is also the basis of the 5’-deiodinase enzymes, which regulate the manufacture of the active T3 from the inactive T4. Without these, the thyroid cannot mate, and we cannot use, thyroid hormones. It is essential an antioxidant and in the proper working with the immune system.
But it doesn’t end there. The enzymes cannot do their job without a number of other chemical substances that must be present. These are called cofactors are required in the manufacture of the hormones & the metabolic processes that are involved in thyroid function. Just a few of these are minerals such as magnesium, manganese, zinc, chromium, iron, copper and calcium. We do not need a lot, but they must be there. Secondly, there are a number of vitamins including B’s, A, E & C.
Hopefully by now you have a greater understanding and a working knowledge of the thyroid gland, its hormones and what they do. Stay tuned for next week’s article in which I’ll talk about when things go wrong and when the thyroid becomes overactive.
Thank you for your attention.
By Steve Hawes
If you are suffering with with any of the issues I’ve discussed in this article or any other health challenges that you would like to tackle with a Functional Medicine/Naturopathic approach then feel free to book a free 30 minute consult with me to discuss your challenges & see if we are the right fit to work together.