Symptoms of Hypothyroidism

I thought I would put this simple blog post on my website. It goes a long way to explain why people with hypothyroidism have such a large range of symptoms and why everyone might experience hypothyroidism in a different way.

The thyroid gland is a small, butterfly-shaped gland that sits in your neck. It is part of your endocrine system.

The simplest definition of hypothyroidism is that the thyroid gland is not able to produce enough thyroid hormones. It is also sometimes called underactive thyroid or simply low thyroid.

The main purpose of thyroid hormone is to keep your metabolism running at a healthy rate. So, it should be no surprise to learn that people with this condition will have symptoms associated with a slow metabolism.

Hypothyroidism is more common than you would believe, and millions of people are hypothyroid and are often not aware of it.

Common causes of hypothyroidism

There are two fairly common causes of hypothyroidism.

The first is caused by inflammation of the thyroid gland, which leaves a large amount of the thyroid damaged (or dead) and incapable of producing sufficient hormone. This is often as a result of autoimmune thyroiditis (also called Hashimoto’s thyroiditis). Hashimoto’s is a form of thyroid inflammation due to the patient’s own immune system attacking the gland.

The second major cause is due to treatments involving the surgical removal or destruction of a portion or all of the thyroid gland. If the amount of thyroid tissue left is not enough to meet the needs of the body, the patient will develop hypothyroidism.  These treatments might be necessary due to thyroid cancer or to remove a risky nodule. It might leave half of the thyroid or it might involve a total thyroidectomy.  If there is some thyroid gland left it may or may not be sufficient to produce enough thyroid hormone.

Goitres and some other thyroid conditions can be treated with radioactive iodine therapy (RAI). The aim of the RAI is to destroy a portion of the thyroid to prevent goitres from growing larger or producing too much hormone (hyperthyroidism). Sometimes RAI can leave a patient without enough thyroid gland and this also results in hypothyroidism.

There are other causes of hypothyroidism beyond the basics above.

Medical categories of hypothyroidism

Hypothyroidism has been classified historically by the medical profession into several categories:

  • Primary hypothyroidism – this is where the thyroid gland fails to produce enough T4 and T3. It is the most common type of hypothyroidism and the patient is said to have an under-active thyroid. It is usually diagnosed through finding high Thyroid Stimulating Hormone (TSH) and low Free T4 (FT4) and low Free T3 (FT3).  If this is caused by Hashimoto’s thyroiditis the thyroid peroxidase autoantibodies (TPOAb) and/or thyroglobulin autoantibodies (TGAb) may be raised.
  • Secondary hypothyroidism – this is less common and occurs if the pituitary gland fails to produce enough TSH.
  • Tertiary hypothyroidism  – occurs due to a fault within the hypothalamus gland, which in turn fails to stimulate the pituitary gland.
  • Secondary and tertiary hypothyroidism may be collectively referred to as central hypothyroidism.
  • Sub-clinical hypothyroidism – is also defined to denote raised TSH above the top of the reference range but with in-range FT4 and FT3.  However, we now know from research that simply having an FT4 and FT3 somewhere in the reference range does not mean you are well (see The Thyroid Patient’s Manual book for more details).

My definition of hypothyroidism

The two main thyroid hormones produced by the thyroid gland are Thyroxine (T4) and Triiodothyronine (T3). It is a scientific fact that T4 only has very weak effects, whilst it is the biologically active T3 that makes our cells work correctly. T4’s main function is to be converted into the active hormone T3. Therefore T4 is often referred to as a pro-hormone, i.e. something that is not really an active hormone unless the body is able to convert it into T3.

If for any reason the action of the thyroid hormone T3 is inadequate to regulate metabolism, this is still hypothyroidism (this broadens the definition to include syndromes like thyroid hormone resistance).

So, therefore, if for any reason an individual does not have sufficient T3 hormone converted from T4, or there are any issues within the cells making T3 hormone less effective, this will still result in symptoms of hypothyroidism.

I use an improved and far clearer definition of hypothyroidism: 

Hypothyroidism is due to the sub-optimal effect of the biologically active T3 within some or all of the cells. In some cases, this is due to too few thyroid hormones, but in every case, it is down to too little effect from T3 within the cells. Many things can cause this. Some examples are:

  • Low cortisol, or more properly, hypocortisolism, as cortisol and T3 work together.
  • Total thyroidectomy or Hashimoto’s thyroiditis (causing thyroid gland damage) – both result in too little T3 (including the loss of T3 converted from T4 by the thyroid gland).
  • Poor conversion of T4 to T3.
  • Some form of thyroid hormone resistance.
  • Central hypothyroidism, resulting in insufficient TSH, and therefore, low T4 and T3.
  • Reduced thyroid gland production of hormones or atrophy.
  • Any other reason that can result in the sub-optimal effect of T3 within some or all of the tissues that cause the symptoms associated with hypothyroidism.

So, when I use the term hypothyroidism I mean the sub-optimal effect of T3 thyroid hormone within some or all of the cells of the body.

This definition includes everything that stops T3 from working well within the cells. It is a more precise definition, and is far less ambiguous than just low thyroid hormones, because sometimes the thyroid hormones may not appear to be low – they just are not working correctly.

Note: some of the issues that result in hypothyroidism may not be visible on any current medical test. This can be the case even though the individual clearly appears to have many of the main symptoms of hypothyroidism.

Why is there such a wide range of symptoms in hypothyroidism?

This is because the active thyroid hormone T3 needs to be at good levels inside all of our cells in order to make them work to their full potential. When T3 is not working optimally in the body, each collection of cells that form glands, organs or tissues may not work at the right metabolic rate and this is when symptoms begin to show up.

Let me provide some examples.

  • If the brain has low or ineffective T3, the person experiencing this may have memory problems, brain fog, fuzzy thinking or poor concentration.
  • If T3 is not sufficient or effective in the gut, the individual may have digestive symptom issues like poor absorption of vitamins and minerals, bloating or indigestion. They may be more likely to develop leaky gut syndrome or be susceptible to infections, candida, bacterial overgrowth or other imbalances.
  • If T3 is low in the body, the liver can be less effective at managing a person’s cholesterol and high cholesterol can be a result.
  • The heart and cardiovascular system also need good levels of T3 thyroid hormone. A variety of cardiovascular problems including high heart rate, low heart rate, heart palpitations, atrial fibrillation, and heart disease may all result if T3 is not at good levels and working effectively within these important cells.
  • Low T3 can also cause bone loss and lead to osteoporosis if the hypothyroidism is not addressed.

In general, the metabolism of an individual person is likely to be low when active thyroid hormone T3 is too low within their cells. The net result for many thyroid patients can be weight gain, fatigue, and low energy, feeling cold and low body temperature.

Therefore, it is not going to be a surprise at all to see that the list of possible symptoms of hypothyroidism is vast.

Symptoms of hypothyroidism (this may not be complete)

  • Abnormal or painful menstrual cycles.
  • Acne and skin infections.
  • Allergies.
  • Anaemia.
  • Anxiety, tension and low stress tolerance.
  • Appetite low.
  • Blood pressure high.
  • Blood pressure low.
  • Blood sugar low (hypoglycaemia) – can cause dizziness, hunger.
  • Bone loss (osteoporosis, osteopenia).
  • Brain fog (see Cognitive Impairment).
  • Changes in voice (slower, rougher).
  • Cholesterol high.
  • Cognitive impairment (brain fog, not thinking clearly).
  • Cold hands or feet.
  • Concentration poor.
  • Constipation.
  • Decreased libido.
  • Depression.
  • Digestive system issues, e.g. absorption of nutrients, bloating, IBS.
  • Eyebrows – loss of outer eyebrows.
  • Fatigue, tiredness- can be severe.
  • Feeling cold, cold intolerance.
  • Feeling hot, heat intolerance.
  • Fingernails – thin, brittle or cracked.
  • Hair – dry or coarse.
  • Hair loss – body, head, legs etc.
  • Headaches or migraines.
  • Heart disease.
  • Heart palpitations.
  • Heart rate high.
  • Heart rate low.
  • Insomnia.
  • Irritability, mood swings.
  • Joint pain or muscle pain or fibromyalgia.
  • Memory poor.
  • Miscarriages (and difficulty in becoming pregnant).
  • Muscles weak or cramping.
  • Myxoedema (swollen skin especially on the face, eyelids, upper arms and hands) – see note below.
  • Pain – or aches, in muscles, joints, fibromyalgia.
  • Reflex responses poor.
  • Relaxing is difficult.
  • Shortness of breath, laboured breathing.
  • Skin dry, rough or pale, itchy.
  • Sleeping a lot.
  • Slow movement.
  • Sore throat.
  • Swallowing problems.
  • Sweating reduced.
  • Temperature low.
  • Tinnitus.
  • Tongue swollen.
  • Vertigo.
  • Voice slower or rougher.
  • Water retention.
  • Weight gain
  • … and I expect some of you will know of other symptoms.

Note: Myxoedema is common in severely hypothyroid patients and it is caused by mucin, which glue-like substance that fills parts of the skin. If myxoedema is present, it is often difficult to slightly lift up areas of the skin, using the thumb and forefinger. The presence of this particular clinical feature, combined with low body temperature and any of the other more common symptoms listed above, used to be the main method of diagnosing hypothyroidism prior to the advent of thyroid blood tests.

If extreme iodine deficiency is a cause of the hypothyroidism, the thyroid can become very large and is then called a goitre. This problem used to be less common, as people used to buy iodized salt. However, the use of less salt or sea salt (which usually does not have added iodine) has resulted in a higher level of iodine deficiency.

Potential dangers of having improperly treated hypothyroidism

Undiagnosed, untreated or improperly treated hypothyroidism is highly detrimental to your health.

In some cases, this can leave the individual with on-going debilitating symptoms that make work or home life very difficult. In the worst cases, it can lead to other health conditions like heart disease, high cholesterol, heart failure, osteoporosis or severe depression. Severe untreated hypothyroidism can even result in coma and death in extreme circumstances.

In many cases, if hypothyroidism is not properly treated the poor patient can continue to struggle with their health for months, years or even decades. It can make having a career or job almost impossible. It can impact relationships and home life. I have worked with so many thyroid patients over the years and the collateral damage improperly treated hypothyroidism can cause is heartbreaking. This is especially sad because hypothyroidism is such a treatable condition.

Note: In this section, I am carefully using the term ‘improperly treated’ because there are a large number of thyroid patients who have been given the most common form of treatment with T4 medication (Levothyroxine/Synthroid) and for various reasons, they are still severely symptomatic and struggle with their health.

A few comments on the diagnosis and treatment of hypothyroidism

Hypothyroidism can often be diagnosed with a simple blood test of all the important hormones including:

  • TSH – the signal from the pituitary gland to request the thyroid gland to make hormones.
  • FT4 – the inactive form of thyroid hormone that in healthy people is converted subsequently to T3.
  • FT3 – the active form of thyroid hormone and one of the most important tests to run.

In some people, diagnosis of a thyroid problem by blood tests alone is not clear-cut and more account needs to be taken of clinical history. It might even require a trial of thyroid hormone as the ultimate diagnostic test.

Hypothyroidism is completely treatable in most patients. However, this is a simplified statement, and it is not always easy. There are several types of thyroid hormone preparations and one type of medicine will not be the best therapy for all patients. In particular, the standard treatment with T4 (Levothyroxine/Synthroid) can leave some patients with on-goings symptoms of hypothyroidism. In which case, one of the other treatments should be considered, e.g. T4/T3, NDT or T3-Only. Unfortunately, in some countries, it is getting more difficult to find doctors willing to explore the use of other thyroid medications.

Many factors must be considered in establishing a sound plan for the treatment of hypothyroidism and it has to be different for every patient. Again, many health systems appear to be moving in the direction of trying to assume that every patient is the same.  This latter trend usually means focus on thyroid laboratory test results as the primary means of assessing whether a thyroid patient is correctly treated or not. Recent research findings have shown the flaws in this latter approach. Research has also shown that the symptoms and signs of the patient ought to be the most important means of assessing treatment success.

Final comments on the symptoms of hypothyroidism

Each individual patient may have any number of the symptoms of hypothyroidism, and they will vary with the severity of the thyroid hormone deficiency and the length of time the body has been deprived of the proper amount of hormone.

You may have one of these symptoms as your main complaint, while someone else will not have that problem at all and will be suffering from an entirely different symptom.

Most people will have a combination of some of these symptoms.

Very occasionally, some patients with hypothyroidism have no symptoms at all, or they are just so subtle that they go unnoticed.

If you have some of these symptoms, you need to discuss them with your doctor.

I do recommend getting enough knowledge so that you can tell if the diagnosis and treatment you are being given appears to be correct for you.

The Thyroid Patient’s Manual book as a resource

The Thyroid Patient’s Manual book is an excellent resource for any thyroid patient learning about hypothyroidism and how to recover from it. It is aimed at patients who suspect they have hypothyroidism, those who have just been diagnosed and are beginning treatment and those who are on thyroid treatment already but are still feeling ill.

The Thyroid Patient’s Manual provides a solid foundation of knowledge about hypothyroidism and treatment. The book includes information on thyroid and adrenal hormones, diagnosis of hypothyroidism and selecting the right treatment. It covers treatment with medications like T4, T4/T3, natural desiccated thyroid (natural thyroid) and T3-Only. It also covers many other problems that might get in the way of your treatment working successfully, and how to deal with them.

Everyone deserves good health!

See also this blog post on the symptoms of high and low cortisol:

Best wishes,


Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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