Thyroid Function – A Multi-Layered Phenomenon Within The Body
Thyroid function is not independent of other glands within the endocrine system, such as the pituitary gland, hypothalamus or adrenals. It needs to be understood that each of these gland, as well as organs such as the liver and kidney play a major role in determining how optimally your thyroid will operate.
The pituitary and hypothalamus, two tiny but very important glands found in the brain, act like a control system to regulate thyroidal performance, much like the brakes and accelerator in a car help control the speed at which that car is going.
Out of all the possible thyroid disorders, hypothyroidism – or an underactive thyroid – is the most common. A strong familial tendency can also exist for this form of thyroid disease.
What Are The Risks Of Developing Hypothyroidism?
It has been found that more women are at risk of developing hypothyroidism than men. Increasing age does increase the risk of developing an underactive thyroid too.
Recent studies in the USA indicate that for those over the age of 60, males came in at an estimated 8% incidence of subclinical hypothyroidism, while women in this age bracket came in at about 15%.
This is significant, because central to the discussion here is the recognition of how crucial a healthy thyroid is to the health of every other organ and gland in the entire body. This is one reason why an underactive thyroid can present with so many different symptoms - or symptoms inadvertently ascribed to a variety of other organ and glandular systems, aside from the thyroid.
Want To Skip Ahead In This 'Thyroid Function' Overview?
The following discussion will obviously flow more logically if you read it as it unfolds below, however, if you're in a hurry and wish to focus on one specific point initially, then simply click on any of these links in order to jump ahead.
Exploring The Thyroid Gland Itself
The thyroid gland is a bi-lobed piece of tissue situated just below the Adam's Apple, at the front of our throat. It secretes two primary hormones called T4 (thyroxine, or tetraiodothyronine) and T3 (triiodothyronine).
Thyroid hormone function is responsible for activating just about every metabolic system in the body, thereby creating energy production, warmth and growth of tissue.
An underactive thyroid, or hypothyroidism occurs if either the thyroid gland itself is unable to produce enough hormone, or - more to the point – if those thyroid hormones aren't able to be used in more peripheral aspects of body function.
On a biochemical level, hormones produced by the thyroid are made up of one tyrosine molecule combined with either 4 or 3 iodine molecules respectively – hence the T4/T3 label. Thyroxine is in fact made up of about 65% iodine.
But this also means that the thyroid gland can't create adequate amounts of these hormones if it doesn't have access to sufficient quantities of both tyrosine (an amino-acid) and iodine (a mineral) – as well as a vast range of co-factors, soon to be explored in greater detail, below and elsewhere on this site.
Most Of The Hormone Produced By The Thyroid Is Inactive
Under conditions of normal thyroid gland function, the thyroid gland produces far more T4 than T3, but for this gland to have any biological effect within the rest of the body's organs, cells and glands, the T4 needs to be broken down to the more active T3 format.
This is because T4 is much less
biologically active than the T3; a crucial point in this discussion.
The conversion of T4 to T3 is achieved by removing one of the iodine molecules from the T4, and accomplished via enzymatic action.
Hence, about 85% of the body's total T3 – the far more active
form of the thyroid hormone - is derived from such conversion, primarily within the liver, kidneys and fat tissues, while only 15% or so of T3 is produced directly
within the thyroid gland itself.
Optimal Thyroid Performance Needs Healthy Kidney Function
The healthy function of the thyroid is also dependent on a well coordinated thyroid and kidney function, way beyond the more simplistic thyroid and iodine connection so often touted.
This is something that far too many doctors don't take into account when they are thinking of testing thyroid function. Chronic kidney disease, like nephritic syndrome, can have a significant, negative impact on overall thyroid function. Similarly, liver problems can impact on how efficiently
the overal thyroid system can operate.
In other words, the reality is that the degree to which thyroid hormone function is adequate within the body is primarily
determined – not necessarily by how much hormone the thyroid gland
produces – but by how much of this hormone is subsequently converted to the active form elsewhere
in the body!
This is a completely separate phenomenon, often not fully grasped by those in medicine, nor tested for via the routine 'thyroid function lab tests', such as the T3 thyroid function or TSH thyroid test. Click here
to further explore the subject of hypothyroidism tests.
However, Converting T4 to T3 Needs Co-factors
This conversion of T4 to T3 is done by the enzyme 5'-deiodinase, but the process is very much dependent on the presence of certain co-factors, such as selenium, zinc, as well as the vitamins A, C, D, B2 and B3. If these nutrients are not available in adequate amounts, then this enzymatic process is impaired, as is the function of the thyroid.
Keep in mind that Australian soils, for instance, like many others in the world are notoriously deficient in selenium. Later on in this site, we'll also explore why, generally speaking, our foods are significantly deficient in many other essential nutrients as well, and why the usual assumption that people in the West attain adequate levels of nutrition may not be quite so true after all.
Indeed, if we aren't getting adequate amounts of these nutrients from our diet, then the resultant suboptimal functioning of the 5'-deiodinase enzyme will have two vital consequences.
Firstly, it will impact on the body's capacity to break down the mostly inactive T4 to the more active T3, resulting in disorders of thyroid function.
Secondly, it will equally impact another crucial process, which is to slow down the decomposition of rT3 (reverse T3), thus causing too high levels of this substance to remain within our system. Unfortunately, this is an aspect to thyroid function seldom understood, let alone discussed or tested for by most doctors dealing with hypothyroidism.
What Is Reverse T3 – Or rT3?
Such increased levels of rT3 can create a significant problem, as reverse T3 is a mirror image molecule of T3 - but inactive
- and thus has a great capacity to compete with, or sabotage the effectiveness of any normal T3 within our system.
The problem is that such reverse T3 – inactive as it may be - is nevertheless able to have a negative feedback loop effect on TSH (thyroid stimulating hormone), with all the associated consequences this entails. But more on the crucial role this inactive rT3 molecule plays within hypothyroidism, elsewhere in this discussion.
How Nutrient Deficiencies Can Play Such A Critical Role In Thyroid Performance
So, if our bodies can't access adequate amounts of these critical nutritional co-factors – unfortunately, an issue mostly ignored by medicine – then we get a dual effect whereby there is too little conversion of the largely inactive T4 levels into the far more active T3, while at the same time increasing amounts of this 'dud' reverse T3 molecule builds up, 'jamming' the system.
Both phenomena therefore cause a decrease
in thyroid function
. Several other factors, such as stress, low calorie diets and liver and kidney disease can also increase this diversion of T4 levels into reverse T3, so this rogue molecule causes considerable repercussions on overall thyroid function.
There is an urgent need for medicine to catch up in regard to the critical role this reverse T3 molecule can play in sabotaging how optimally a thyroid gland will function.
Many Layers To How A Healthy Thyroid Operates
It's really important to bring to your attention the reality that overall thyroid function is so much more than just how much thyroid hormone (as measured by the 'usual' blood tests) the thyroid gland produces. This can't be stated often enough!
There are a range of other critical factors that need to be taken into consideration when it comes to truly understanding how functional,
or effective the thyroid gland and its hormone secretions are.
The Role Of Cell Membranes In Healthy Thyroid Functioning
For instance, T3 - the most active form of thyroid hormone - is a large molecule, and has problems getting across cell membranes. It needs carrier molecules for this, as well as healthy, functional cell membranes.
However, a classic 'fast-food', Western diet inevitably results in a high intake of the wrong type of fatty acids, causing cell walls and membranes to become too 'stiff', which in turn inhibits proper diffusion of substances into and out of cells.
Hence, if these carrier molecules are low in number, or faulty in function, or the cell membranes have permeability issues, then a situation occurs where there may be adequate to high levels of T3 in the blood
, but low levels inside the cell
So, the TSH and T3 levels may indeed be 'normal' according to a thyroid blood test, yet the cells
are starving for T3!
By the same token, it also needs to be realized that even when T4 (the more in
active form of thyroid hormone) gets inside the cells, there is yet another step that needs to be achieved before it will work.
In other words, there is still a need for this T4 - (especially when delivered into the body via the synthetic, drug version, like Oroxine, Thyroxine, etc.) - to be broken down to the more active T3 format, before migrating to the cell nucleus where it then initiates mitochondrial ATP production – the generation of cellular energy, which keeps us alive!
Healthy Thyroid Performance Depends On Healthy Adrenal Function
Another aspect of optimal thyroid function is the concurrent need for healthy adrenal function. To ensure efficient secretion of thyroid hormones, a healthy sympathetic nervous system response (the ability to handle stress) is required as well.
However, for those people with exhausted adrenals, they lack the ability to mount an adequate response to stress, thus further undermining thyroid function.
In addition, cortisol – produced by the adrenals – regulates the number
of T3 receptors (docking stations) inside
the cell, as well as their activity
The problem is that if a person is adrenally depleted - a widespread phenomenon in our high-stress modern lives – this can eventually result in not enough cortisol production by the adrenal glands.
Subsequently, the number and function of T3 receptor sites inside the cell nucleus will also be decreased, which in turn means too little initiation of mitochondrial energy production
This means that the overall function
of thyroid hormones is therefore impaired, often resulting in subclinical hypothyroidism; in other words, an underactive thyroid not picked up by 'regular thryoid blood tests.
Too Little Or Too Much Cortisol Affects Optimal Thyroid Operation
Therefore, it's really important to understand that too high or too low cortisol levels will negatively affect receptor
activity, and hence thyroid function
The former usually occurs due to medically prescribed cortisone therapy, while the latter more due to insufficient cortisol production found in adrenal depletion.
Within medicine, cortisone therapy is known to decrease adrenal function, but what is not adequately taken into consideration is that such therapy can equally, although indirectly decrease thyroid function too
The importance of an adrenal link to poor thyroid function will be delved into more fully in the 'Treatment' section of this site.
Limitations Of Thyroid Blood Tests For Diagnosing Subclinical Hypothyroidism
When we explore various thyroid blood tests, elsewhere
on this site, you'll see that solely depending on the use of the TSH thyroid test (thyroid stimulating hormone), T3 thyroid function, or T4 levels for diagnosing a subclinical
level of hypothyroidism is completely inadequate.
This reality is exacerbated when a patient is simultaneously dealing with an iodine deficiency. A seemingly weird thing happens when the body is experiencing such a deficiency.
Why An Iodine Deficiency Can Have Such Major Repercussions
If our bodies are not getting adequate iodine from our diet, then the deiodinase enzymes present inside cells will grab T3 (remember, the active
form of thyroid hormone!) as it goes into a cell, in order to scavenge iodine from it
In hypothyroidism this means that whatever little active
thyroid hormone is floating around the body is now compromised even more, resulting in further reduced thyroid function!
On one level this may not make biological sense, but nevertheless this is what can happen when the body is deficient in iodine.
The result of this phenomenon is that although thyroid function blood tests will show adequate T3 in the blood
, such scavenging for iodine - if a person is in iodine deficiency - will result in the destruction of T3 hormone within the cell
. This aspect remains 'invisible' if only 'routine' thyroid blood tests are used.
This subsequently produces a decreased level of available, active
T3 through which to trigger cellular activity, a key function of thyroid hormones. This in turn causes a lowered metabolic rate
, and hence low body temperature – a major characteristic of hypothyroidism.
But the most crucial point to take home is that such decreased thyroid function is occurring despite adequate levels of T3 in the blood
Levels Of Hormone Found In the Blood May Not Automatically Be The Same In The Cell
It is also important to realize that the cells of the body, and the blood flowing within the body, need to be seen as two separate, but interacting compartments. Each affects the other, but they are not inherently the same.
Hence, one cannot automatically assume that what is found in one compartment, for example, the blood – via various thyroid tests - will exist in equal amounts within
the cells of the body.
This is where the medical model and understanding of hypothyroidism, or a so called underactive thyroid, fails miserably.
The sad reality is that this also means many people with genuine thyroid symptoms due to genuine thyroid function problems go undiagnosed – if a thyroid blood tests is the sole yardstick from which to make a medical diagnosis of subclinical hypothyroidism as a health issue.
I hope this discussion has been useful for you in better understanding the multitude of layers associated with hypothyroidism, and why – despite suffering many of the symptoms of an underactive thyroid – your doctor keeps dismissing this option, because your tests keep coming back as 'normal'.
With the self-empowering information you've just accessed, as well as via the many links provided above and elsewhere on this site: www.Holistic-Hypothyroidism-Solutions.com , you'll find yourself in a much more empowered position from which to finally get a more definitive diagnosis of hypothyroidism, plus a better understanding of the many ways in which this health condition can definitely be successfully treated.
Some Final Factors Affecting Thyroid Peformance To Think About
You can explore other factors affecting thyroid function in various different parts of this site. Below, is a brief listing of those factors, with links to their appropriate pages.
(Please note that this is a recently launched site (May 2012), with much more information to be added over the coming months.
If some of the links haven't yet been activated, but you're interested in a particular topic, and would like to be advised when that information is uploaded, then do fill out the 'Contact Form' below, and you'll be advised of each new update to this site's ever-increasing amount of self-empowering information)
Thyroid Resistance As An Important Phenomenon Driving Hypothyroidism
Thyroid resistance occurs when the hormones produced by the thyroid gland don't work effectively in peripheral areas of body function.
In other words, one scenario is where such hormones are themselves dysfunctional and incapable of docking onto various cellular receptor sites, through which to activate cellular metabolism.
Another possibility is that the receptor sites are faulty, thus preventing proper activation of cellular metabolic function, despite plenty of functional thyroid hormone being available.
One other option to consider is that the mainly inactive T4 thyroid hormone is not adequately converted within the liver, kidneys or fat tissues to the far more active T3 format. Click here to read more
Thyroid function & Dietary Factors Such As Soy Or Cruciferous Vegetables
Certain foods have been found to have an anti-thyroid function effect, and if ingested on a regular basis can have serious repercussions on how well the thyroid gland is able to function. This factor will be explored in greater detail in the: 'Hypothyroidism & Nutrition'
part of this website. [this link still needs to be activated]
Thyroid Function & Autoimmunity
Hashimoto thyroiditis, one of the autoimmune diseases affecting the thyroid gland, is a significant cause of hypothyroidism in the USA.
Sometimes pregnancy can set off an autoimmune reaction towards the thyroid gland, with about 2% of pregnant women in America manifesting poor thyroid function during this very significant time, with serious ramifications for the fetus.
Other than harsh, immunosuppressive therapies, or regular monitoring, modern medicine often states that there is little they can do to truly cure autoimmune thyroid disorders.
Yet from a naturopathic perspective, there is so much that can be done to not just stabilize, but even reverse various autoimmune diseases of the thyroid!
This will be explored in greater detail in: 'Autoimmune Diseases'
. [this link still needs to be activated]
Thyroid Function & Artificial Sweetners
Clinical experience shows that various artificial sweeteners, such as aspartame, can precipitate an over
active thyroid gland.
It has also been suggested that aspartame interferes with the production of serotonin, which is a hormone known to affect pituitary control of the thyroid gland.
Although this site is primarily about hypo
active thyroid), it is important to bring up this connection between artificial sweeteners and an over
active thyroid, or Graves Disease.
The simple reason is that a common medical treatment for this condition is to use radioactive iodine – or surgery – to partially destroy the thyroid gland; an irreversible situation with critical repercussions on overall health. This is a major medical
cause of an underactive thyroid.
This aspect will be further discussed in this site's section on: 'Hypothyroidism & Nutrition'.
[this link still needs to be activated]
Vitamin D & Thyroid Function
Vitamin D deficiency can be another important factor in determining the level of efficient thyroid function. Much research exists connecting deficient vitamin D levels with a tendency to autoimmunity, as well as insulin resistance... which in turn affects thyroid function. All this and more will be further delved into, in the section on: 'Hypothyroidism & Nutrition'.
[this link still needs to be activated]
Medical Drugs & Thyroid function
Beta blockers decrease thyroid function, as does a heart drug called Amiodarone. Quite a number of medical drugs, like antiepileptic drugs, cortisone, propylthiouricil, or lithium can be associated with poor thyroid function.
It's worth repeating that radioactive iodine, often used to treat an over
active thyroid – called hyper
thyroidism, or Graves Disease – can cause so much damage as to generate a subsequently underactive thyroid function.
The way in which medical drugs affect thyroid function will be explored in greater detail in: 'Hypothyroidism Causes.'
[this link still needs to be activated]
Thyroid Function & Nutrition
On a global level, the primary cause of hypothyroidism is an iodine deficiency. However, a wide range of other nutrient deficiencies can also play a significant role in creating an underactive thyroid. Find out more at: 'Hypothyroidism & Nutrition'.
[this link still needs to be activated]
Thyroid Function And the Halogens – Fluoride, Chlorine and Bromine
Fluoride, chlorine and bromine play an especially noxious role in hypothyroidism, strongly affecting thyroid function from several different aspects.
This is an important factor to consider for many in the West whose drinking water has been 'medicated' with both fluoride and chlorine, let alone the amount of bromine found as a contaminant in many of our household goods.
By having a better understanding of why these substances are so toxic to the thyroid will also help you make more empowering choices in your daily life. Read more at: 'Hypothyroidism & Environmental Factors'.
[this link still needs to be activated]
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