Having an underactive thyroid is so much more common than people realise. In fact, it is estimated that one in eight women will develop a thyroid disorder in their lifetime. Hypothyroidism is approximately ten times more prevalent in women than men. The problem is that so many women are walking around daily, feeling like death, completely unaware that their thyroid is the driving force behind their symptoms. I was one of these women for over five years, I had no idea. I was diagnosed with Fibromyalgia and yet, I knew there was something else going on. The problem was that my routine thyroid blood markers (TSH and T4) were always ‘normal’ and still are!
What is Hypothyroidism?
Hypothyroidism is a common endocrine condition where the thyroid is either not producing adequate levels of thyroid hormone or thyroid hormone is not reaching the target tissue in the body. Most cells in the body have thyroid receptors, so when thyroid hormone becomes scarce, the implications can be far reaching.
Hypothyroidism can either be primary or the result of secondary causes.
- Autoimmune thyroiditis, known as Hashimoto’s
- Severe iodine deficiency or mild to severe excess
- As a result of thyroid ablation or surgery, usually to treat hyperthyroidism, goitre or thyroid cancer
- Drug induced – medication like lithium, sodium valproate (anti-epileptic) and more
- Transient thyroiditis in infants post birth
- Thyroid cancer
- Other autoimmune conditions, such as Sarcoidosis and Lupus
- Hypothalamic failure or dysfunction
- Pituitary disfunction
- Drug induced, such as dopamine or somastatins
It is estimated that iodine deficiency and autoimmune thyroiditis, known as Hashimoto’s thyroiditis, account for the vast majority of cases of primary hypothyroidism. Changes in agriculture in the 1950s have led to re-emergence of iodine deficiency. A third of the world’s population live in iodine-deficient areas. Iodine deficiency can have devastating consequences during pregnancy and cognitive development in neonates.
It is estimated that 44% of school-age children still have insufficient iodine intake in Europe. In iodine-sufficient countries, it appears that the prevalence of hypothyroidism ranges from 1-2%, but then only increases to 7% between the ages of 85-89. The body’s ability to convert T4 to T3 reduces with age, which can lead to increased susceptibility with age.
How does your thyroid work?
Every cell in your body depends on thyroid hormone to help regulate metabolism. Thyroid hormone directly impact digestion, the heart, muscles, brain and bone development and function.
The thyroid is under the control of the pituitary, a small gland about the size of a pea, located at the base of the brain. When levels of thyroid hormone (T4 and T3) drop too low, the hypothalamus produce Thyroid Releasing Hormone (TRH), which in turn prompts the anterior pituitary to produce Thyroid Stimulating Hormone (TSH) and prolactin. The TSH then stimulates the thyroid to produce thyroxin (T4) and triiodothyronine (T3) thereby raising blood levels of thyroid hormone.
If you think of your thyroid gland as a furnace and the pituitary gland as the thermostat. Thyroid hormones are like heat and when the heat gets back to the thermostat it turns the thermostat off. As soon as the room cools, the thyroid levels drop and then the thermostat turns back on again and TSH increases, and the furnace (thyroid) produces more heat (T4 and T3).
How does your thyroid make T4 & T3?
The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormone (T4 & T3). When the body doesn’t have sufficient levels of iodine, it can lead to decreased production of T3 and T4. In fact, it is the reduction in iodine in our food globally and especially in specific regions that has led to increased prevalence of hypothyroidism. Hence the reason why iodised salt became essential. It is really important to note that iodine can also be quite problematic for people with Hashimoto’s, so don’t rush out and stock up on iodine, until you know what’s actually going on with your thyroid. I am super sensitive to iodine and even the smallest amount of iodine triggers a reaction in me.
Thyroid cells are the ONLY cells in the body that can absorb iodine. These cells combine iodine and the amino acid, tyrosine, to make T3 and T4, which is then released into the blood stream and transported throughout the body where they control metabolism (converting oxygen and calories to energy).
Your thyroid will produce approximately 80% T4 and only 20% T3, yet it is worth keeping in mind that T3 is about four times as strong as T4 and is your active thyroid hormone.
Most of the thyroid hormone circulating your blood is T4 and your cells therefore rely on the enzyme 5-deiodinases (D1 and D2) to covert T4 to the more powerful and active T3. In order for this process to occur, these 5-deiodinases, which contain selenium, require sufficient selenium stores in the body. So just like your body needs sufficient iodine to make thyroid hormone, your body needs to have sufficient selenium and zinc stores to ensure that you can convert T4 to T3.
Functions of your Thyroid
Thyroid hormones primarily act to regulate the metabolic rate of cells and tissues and thereby are involved in growth, development, reproduction and metabolism. Thyroid hormones also stimulate thermogenesis, thereby helping to regulate temperature.
The function of the thyroid is linked to the central nervous system, cardiovascular system, reproductive system, digestive system, in fact it impacts the entire body.
This can make it challenging as symptoms can be far reaching and as a result very often assigned to another ‘disorder’.
Signs that your thyroid could be under-active
- Persistent fatigue
- Unexplained weight gain
- Brain-fog or memory loss
- Muscle and joint aches and pains
- Hair loss
- Low mood
- Slow heart beat
- Difficulty regulating temperature
- Intolerance to cold
- Dry skin
- Internal tremors
- Digestive issues
- Lack of motivation
- Low libido
- Thinning of outer part of eyebrow
- Enlarged thyroid
- Sore throat
How can the doctor tell if your thyroid in under-active?
The only two markers currently being tested within conventional health care is TSH and T4. Whilst these markers are important and should be tested, they most certainly don’t provide a comprehensive overview of your thyroid health.
Despite the fact that the thyroid produces mostly T4, we know that T3 has the most powerful physiological function. This therefore begs the question as to why T3 levels aren’t tested? It is also worth adding thyroid hormone are mostly bound to proteins (99.8%), leaving only a small amount available in their free form.
The important point is that only free T3 and free T4 have biological actions, thereby meaning, that only the free T3 and T4 has the ability to bind to their respective receptors. This explains why free T4 is being tested.
Furthermore, the active thyroid hormone in the body is free T3.The presence of free T3 depends on the conversion from T4 with the help of the enzyme 5-deiodinases (D1 and D2). This function basically allows the different tissue in the body to self-regulate its exposure to free T3. This is important as different tisues require different levels of T3.
Conventional Thyroid Panel
When your doctor test your thyroid function, the following markers and reference ranges are used:
TSH 0.20 – 5.00 mu/L
Free T4 9.00 – 24.00 pmol/L
Sadly, these reference ranges are based on ‘sick’ people and not focussed on identifying early warning signals that the thyroid is becoming dysfunctional or diseased. By the time your TSH is over 5.00 mu/L, your thyroid has already been under-active for a very long time.
Your doctor will diagnose you with an under-active thyroid/hypothyroidism if your TSH concentrations are above and free T4 levels are below the above reference range. Your doctor is likely to prescribe a form of thyroid therapy, such as Levothyroxine or Synthroid, which is a T4 replacement therapy. Whilst thyroid therapy can be life altering for so many women, it doesn’t address the underlying root cause.
Functional Medicine and Thyroid disease
In functional medicine, we believe in understanding the root cause of someone’s health problems. We use the symptoms as a compass to signal where the body is out of balance. In the case of the thyroid, the focus is very much on understanding why the thyroid is struggling or imbalanced.
Having a diagnosis of hypothyroidism or Hashimoto’s disease doesn’t mean you know what is wrong with you. In fact, just like in conventional medicine, you have simply been put in a box with a label. Whilst we try really hard in functional medicine to break away from the ‘disease-label model’, it is still important to ensure that testing is done to understand what’s going on.
Functional testing can add significant value to understanding the severity of the problem, but also to get insight into whether the problem is functional or autoimmune. The way we deal with autoimmune disease is very different, so it is imperative to establish whether someone has Hashimoto’s thyroiditis or just an underactive thyroid. The fact that approximately 80% plus people with hypothyroidism have Hashimoto’s disease, makes it is essential that we test antibodies in all cases of suspected thyroid disorder.
Thyroid functional lab tests are very comprehensive and generally test TSH, T4, free T4, free T3, reverse T3, TPO and TGA (both thyroid antibodies).
Not everyone believes that reverse T3 is important, but I do like to understand the entire profile of my clients’ thyroid health. You often see reverse T3 high when your body is under stress or dealing with significant inflammation, which will further reduce T3 activity. I also like to use this in conjunction with adrenal profile testing, which I believe to be a critical adjunct to thyroid testing.
Understanding the full thyroid profile then enables me to establish how best to support my clients’ symptoms. As mentioned before, this is only the starting point. The hard work lies in trying to establish, why the thyroid is performing in this way.
There are many potential drivers for thyroid imbalance, which I will discuss in a separate post.
How do you know if your thyroid in underactive?
Hopefully you now have a better understanding of some of the key symptoms and test markers to look out for. We need to break away from putting people like myself and potentially you at risk of slipping through the net without an early diagnosis and the right support.
I kept visiting my doctor for years, only to be told that my thyroid was normal. It wasn’t until years later, when I finally paid for a functional test, that I learnt that my diagnosed ‘Fibromyalgia’ symptoms was Hashimoto’s disease all along. At this point, after years of clean eating and living, my TPO antibodies were a whopping 600. I shudder to think what they would have been when I was too ill to function.
If you suspect that your thyroid is not working, then I urge you to get it tested. Fatigue, dry skin, depression, brain fog, brittle nails, hair loss, constipation, decreased sex drive, always being cold, weight gain or difficulty losing weight, thinning at the edges of your eyebrows is not normal, so don’t let these symptoms linger.
If you want more information on testing or need support to get your thyroid health back on track, then get in touch.