Hypothyroid signs and symptoms

Thyroid Disease

What is the thyroid?

The thyroid is a small gland, shaped like a butterfly, that rests in the middle of the lower neck. Its primary function is to control the body’s metabolism (rate at which cells perform duties essential to living). To control metabolism, the thyroid produces hormones, T4 and T3, which tell the body’s cells how much energy to use.

A properly functioning thyroid will maintain the right amount of hormones needed to keep the body’s metabolism functioning at a satisfactory rate. As the hormones are used, the thyroid creates replacements.

The quantity of thyroid hormones in the bloodstream is monitored and controlled by the pituitary gland. When the pituitary gland, which is located in the center of the skull below the brain, senses either a lack of thyroid hormones or a high level of thyroid hormones, it will adjust its own hormone (TSH) and send it to the thyroid to tell it what to do.

What is thyroid disease?

When the thyroid produces too much hormone, the body uses energy faster than it should. This condition is called hyperthyroidism. When the thyroid doesn’t produce enough hormone, the body uses energy slower than it should. This condition is called hypothyroidism. There are many different reasons why either of these conditions might develop.

Who is affected by thyroid disease?

Currently, about 20 million Americans have some form of thyroid disease. People of all ages and races can get thyroid disease. However, women are 5 to 8 times more likely than men to have thyroid problems.

What causes thyroid disease?

There are several different causes of thyroid disease. The following conditions cause hypothyroidism:

  • Thyroiditis is an inflammation of the thyroid gland. This can lower the amount of hormones produced.
  • Hashimoto’s thyroiditis is a painless disease of the immune system that is hereditary.
  • Postpartum thyroiditis occurs in 5% to 9% of women after giving birth. It is usually a temporary condition.
  • Iodine deficiency is a problem affecting approximately 100 million people around the world. Iodine is used by the thyroid to produce hormones. Although prevalent before the 1950s in the United States, iodine deficiency has been virtually wiped out by the use of iodized salt.
  • A non-functioning thyroid gland affects one in 4,000 newborns. If the problem isn’t corrected, the child will be physically and mentally retarded. All newborns are given a screening blood test in the hospital to evaluate thyroid function.

The following conditions cause hyperthyroidism:

  • With Graves’ disease, the entire thyroid gland might be overactive and produce too much hormone. This problem is also called diffuse toxic goiter (enlarged thyroid gland).
  • Nodules might be overactive within the thyroid. A single nodule is called toxic autonomously functioning thyroid nodule, while several nodules are called a toxic multi-nodular goiter.
  • Thyroiditis, a disorder that can be painful or painless, can also release hormones that were stored in the thyroid gland causing hyperthyroidism for a few weeks or months. The painless variety occurs most frequently in women after childbirth.
  • Excessive iodine is found in a number of drugs such as Amiodarone, Lugol’s solution (iodine), and some cough syrups, and might cause the thyroid to produce either too much or too little hormone in some individuals.

What are the symptoms of hypothyroidism and hyperthyroidism?

The following are symptoms for hypothyroidism:

  • Fatigue
  • Frequent, heavy menstrual periods
  • Forgetfulness
  • Weight gain
  • Dry, coarse skin and hair
  • Hoarse voice
  • Intolerance to cold

The following are symptoms for hyperthyroidism:

  • Irritability/nervousness
  • Muscle weakness/tremors
  • Infrequent, scant menstrual periods
  • Weight loss
  • Sleep disturbances
  • Enlarged thyroid gland
  • Vision problems or eye irritation
  • Heat sensitivity

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If there is not enough thyroid hormone in the bloodstream, your body’s metabolism slows down. This condition is called hypothyroidism (also known as underactive thyroid disease). It is a relatively common disease that affects people of all ages and races. However, women, especially older women, are more likely to develop hypothyroidism than men are. Hypothyroidism can affect up to 20% of women over the age of 50.

What is the thyroid gland?

The thyroid is a small butterfly-shaped gland located just below the Adam’s apple. The primary function of the thyroid is to control the body’s metabolism (the rate at which the cells perform duties essential to living).

To control the metabolism, the thyroid produces the hormones T4 and T3, which tell the body’s cells how much energy to use. These hormones act on almost all the tissues and organs of the body. They help control your body temperature, influence your heart rate, and regulate the production of protein.

A properly functioning thyroid will maintain the right amount of hormones needed to keep your body’s metabolism functioning at a satisfactory rate. As the hormones are used, the thyroid creates replacements. The quantity of the thyroid hormones in the bloodstream is monitored and controlled by the pituitary gland, which is located in the center of the skull below the brain. When the pituitary gland senses either a lack of thyroid hormone or too much, it will adjust its own hormone (thyroid stimulating hormone, or TSH) and send it to the thyroid to tell it what to do.

The most common cause of hypothyroidism is a disorder known as autoimmune thyroiditis (Hashimoto’s disease). The body’s immune system causes the thyroid gland to lower the amount of hormones produced. Hashimoto’s disease can be hereditary, meaning it runs in families.

Thyroiditis (inflammation of the thyroid) can also occur after pregnancy or a viral illness. Treatment with radioactive iodine for hyperthyroidism (overactive thyroid) can result in hypothyroidism. Additionally, several medicines (lithium and amiodarone) can affect thyroid function.

Another potential cause of hypothyroidism is a problem with the pituitary gland. The pituitary might fail to stimulate the thyroid to make enough hormones to meet the body’s needs.

The symptoms of hypothyroidism usually develop slowly over a number of years and include:

  • Fatigue
  • Numbness and tingling in hands
  • Constipation
  • Weight gain
  • Intolerance to cold
  • Dry, coarse skin and hair
  • Decreased sexual interest
  • Frequent, heavy menstrual periods
  • Forgetfulness

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Getting a Diagnosis
and Starting Treatment

It’s quite possible that you have been ill for some time and have visited your General Practitioner (GP) on many occasions regarding some symptom or other.

If you have read our information and if you have a lot of the symptoms of hypothyroidism (Myxoedema/underactive thyroid) or hyperthyroidism (overactive thyroid), think about making an appointment to go back to your GP and discuss some options. Your doctor will need all the information about your health that you can give. Give your doctor copies of anything you have written down so that hthey can read it and put a copy in your record. It’s better to be specific about your symptoms or your doctor may miss something.

For instance, if you have to have the heating up high in your house all the time because you are cold and people make comments about this, tell your doctor. If you find yourself going to bed early, waking up late and sleeping all afternoon because you are so tired, tell your doctor. If you walk around all day in shorts and a t-shirt and have the windows open all the time, even in winter, because you are always very hot, tell your doctor.

Try to be clear and precise when you speak to your doctor. It might be an idea to take someone with you if you can, not only for support but also so that they can remember what has been said. How often have you come out of the doctor’s surgery and forgotten nearly everything that was said to you? This person may also be able to confirm what you are telling the doctor.

Undiagnosed hypothyroidism or hyperthyroidism can cause a great strain on the heart. Hypothyroidism can cause coronary atherosclerosis (furring up of the arteries) due to high cholesterol levels. Dr Rowan Hillson tells us in her book, “Thyroid Disorders”, “Lack of T3 and T4 alters fat metabolism… and this can lead to furring of the coronary arteries (coronary atherosclerosis) and reduction of the blood supply to some of the heart muscle. This causes angina… – pain in the chest on exercising, which is usually relieved by rest. Coronary atherosclerosis can cause angina, a heart attack or coronary thrombosis.”

Hyperthyroidism causes the heart to beat faster and increases the risk of stroke as well as atrial fibrillation (fast and irregular heartbeat).

It is therefore very important not to miss a diagnosis of hypothyroidism or hyperthyroidism.

Thyroid UK suggest a step by step approach:

Before you make the appointment:

  • Find out whether you have had any previous thyroid tests done. If you have, find out exactly which tests you have had done and make a note of them. The most common thyroid tests are Thyroid Stimulating Hormone (TSH), Free T4 (FT4) and Free T3 (FT3). Sometimes the thyroid antibody tests will be done – Thyroid Peroxidase (TPO) and Thyroglobulin (TgAb) – but not often. Sometimes the receptionist will give them to you over the phone but you will probably need to go into the surgery and ask for your test results.
    You have a right to see your medical records under the Data Protection Act 1998. Guidance on The Data Protection Act 1998 can be found at: https://ico.org.uk/for-the-public/personal-information/
  • Do not just accept “normal”. You should always ask for the actual figures of your test results – your level as well as the ranges. Be aware that different areas in the country use different test ranges so one TSH test range might be 0.5 – 5.0 but in another area the TSH range might be 0.4 – 4.0. You could be “borderline” (near the bottom or top of the range) or have “subclinical hypothyroidism” (high TSH and normal FT4) or “subclinical hyperthyroidism” (low TSH and normal FT4) and not be aware of this because you have not been given the ranges of the tests. Subclinical thyroid disease is not usually treated although treatment may be useful.
    The 2006 Thyroid Function Test Guidelines state, “There is no evidence to support the benefit of routine early treatment with thyroxine in non-pregnant patients with a serum TSH above the reference range but <10mU/L.” which in layman’s terms means that patients who have a TSH of less than 10 need not be treated because it doesn’t help. However, they also state that, “Physicians may wish to consider the suitability of a therapeutic trial of thyroxine on an individual patient basis.”
    If your TSH test is above the range but less than 10, it might be an idea to discuss these Guidelines with your doctor as it may persuade them to give you a trial of thyroxine. In our experience, patients with signs and symptoms of hypothyroidism who have a normal TSH and low normal FT4 also benefit from a trial of thyroxine.
    Your FT4 could be nearer the top of the range usually and therefore with a low normal level, you feel quite ill. As you probably did not have your thyroid tested when you were well, you will never know if this is the case. Discuss the possibility of a trial of thyroxine with your doctor if you have low normal FT4 levels.
  • TSH has a circadian rhythm (24 hour cycle) and levels peak between midnight and 6am. T3 has a similar circadian rhythm. It is therefore a good idea to have your thyroid tests done at the same time of day each time as your levels may differ at different times of the day.
  • Start to keep a diary and include your thyroid test dates, thyroid test results and their ranges, any other tests such as B12, folate, ferritin, cholesterol etc that you have had done recently, pulse rate and weight. Your diary will soon start to show a picture of your health and whether things change or not.
  • Tick off all the symptoms you have on our Hypothyroidism or Hyperthyroidism Symptom List, adding any symptoms you have that are not listed and rate them on a 1-10 scale with 10 being the worst. Do this at regular intervals – at the same time as you have tests done is a good idea and then you can see how you are feeling and tie this in with test results. This will also help you know at which level you feel best for future reference.
  • Find out as much as you can about the thyroid before your appointment so that your doctor can see you are well informed. Copy information from our Information Pack or from thyroid books and highlight the relevant areas so that you can show these to your doctor.
  • Make a list of questions you want to ask your doctor. Make sure you have space for your answers. Add to the list as you remember things.

At the appointment:

  • Give your doctor a copy of your diary and list of symptoms and explain some of them if necessary. Explain exactly how your symptoms are affecting your quality of life and your work – explain the things you used to be able to do but can’t now. “Before” and “after” photos sometimes help too.
  • Ask your doctor if you can have all the thyroid tests available if you have not had these done. Many doctors only do the TSH test. However, some doctors believe that all the tests need to be done i.e. TSH, FT4, FT3, TPO and TgAb. This will ensure that other thyroid problems are not missed such as non-conversion of T4 into T3, Hashimoto’s disease, central (secondary) hypothyroidism or Graves’ disease. Be aware, though, that your GP may ask for FT3 to be done but the lab that the test form goes to may refuse to do it. You could try asking if your GP will add something to the test form to say “Thyroid function test including FT3 & FT4, regardless of the TSH reading.” as this may help.
    There is a paper discussing the fact that early treatment of euthyroid (normal thyroid hormone levels) Hashimoto’s Thyroiditis with thyroxine may slow down the disease process. There is also evidence that shows that anti-thyroid antibodies can cause infertility and miscarriage. It is therefore a good idea to find out if you have high thyroid antibodies and discuss treatment with thyroxine with your doctor.
    If your doctor is not able to do some of the tests on the NHS ask if you could have the blood drawn at the surgery in order to have private tests done by a diagnostic lab such as Genova Diagnostics (see Genova Diagnostics leaflet). Sometimes the NHS lab will do private tests if asked.

  • Ask your doctor to check your B12, folate, ferritin and Vitamin D levels as deficiencies of any one of these could be a reason for your ill health. The symptoms for Pernicious Anaemia are very similar to those of hypothyroidism. The range for B12 is quite wide and some patients feel much better at the upper end of the range. The BBC produced a programme regarding this – “Inside Out 30 Oct 2006 – Vitamin B12 Deficiency” – which you may be able to watch online.
    You can find more information on the website of the Pernicious Anaemia Society –
  • There has been a lot of research recently, showing that the serum B12 test is inadequate and a new test has now been developed to test for holotranscobalamin only. This is not available generally on the NHS. However, the Nutristasis Unit at St Thomas’ Hospital now provides this test. It is slightly more expensive than a standard serum B12 test. To obtain this test you need to get a signed letter from your GP requesting the test and you must attend the phlebotomy department at St Thomas’ Hospital.
    For more information on the Active B12 (holotranscobalamin) test at St Thomas’ Hospital please go to:

    or email the Nutristasis Unit at [email protected]
    or phone Denise Oblein on 020 7188 7188.
    Or you can visit the Axis-Shield website: www.active-b12.co.uk Registration Forms are available from the Nutristasis Unit or Denise Oblein.

  • The Active B12 test is also now available as a private home test kit through the private testing company Blue Horizon Medicals. For more info about Blue Horizon, and to download the Thyroid UK list of discounted Blue Horizon tests, go to the Home Blood Test Kit section
  • If your doctor suggests seeing a consultant in a different field to endocrinology, perhaps a rheumatologist, it might be a good idea to do this. It will either show up another health problem or it will rule it out completely. This often happens when patients are referred to psychiatrists.

If you are diagnosed:

  • Once you have been diagnosed, try to see the same GP/endocrinologist every time you make an appointment. It makes it much easier to discuss your progress.
  • Be aware that if you are diagnosed with hypothyroidism (myxoedema), you are entitled to free prescriptions. Ask your GP or NHS hospital for an FP92A application form. The form tells you what to do. A certificate/card will be sent to you upon receipt of a properly completed application form.
  • If your doctor diagnoses you with thyroid disease, they will probably start you on treatment. Information on the different treatments is found in our leaflets, Hypothyroidism and Hyperthyroidism. Treatment is usually started with small dosages. You will probably be told to be tested in two or three months and then make another appointment. Your doctor will then look at your test results, discuss your symptoms with you again, especially any improvement, and then make a decision as to whether or not to increase or decrease your dosage.
    Your doctor will decide when to keep you on a particular dosage. This is usually decided by looking at the blood tests. However, some people still remain ill at this point. If this happens, we suggest the following:


  • You will need to be patient as it can take a long time to improve. It takes about 7-10 days for the levothyroxine to enter the body’s cells properly so don’t expect any improvement before then. Some people do see improvement in two weeks but for many it can take several weeks and even then, only some of the symptoms will improve in the beginning. If you have been ill for a very long time, it can take many months before you are back to normal.
    You may find that you have some good days and then some bad days again. You need to be careful not to overdo it until you have found the right level for you (your set point).
  • Ensure that you are taking your levothyroxine with water, on an empty stomach. Wait for at least 30 minutes before you eat.
  • Ensure that you do not take calcium carbonate (found in calcium and other supplements and antacids) within four hours of your levothyroxine as this affects absorption.
  • Ensure that you do not take iron supplements within two hours of your levothyroxine.
  • Other drugs that have been reported to reduce levothyroxine absorption include ciprofloxacin (Cipro), raloxifene (Evista) and Orlistat/Alli (Xenical) so be aware that it may be better to take these drugs away from your levothyroxine.
  • Proton pump inhibitors, statins and oestrogens may reduce the effectiveness of levothyroxine.
  • Coffee can also interfere with absorption of T4 so do not take your levothyroxine at the same time as drinking a cup of coffee – it’s probably best to wait at least an hour before you drink coffee.
  • Try taking your levothyroxine at bedtime as there was a small study that showed this benefited some patients.
  • If you still feel ill it could be for various reasons. Some people do not feel well on a particular brand of levothyroxine. The main brand in the UK used to be Eltroxin and some people felt better on this. However, this is no longer produced. The other brands are all called generics (copies). Some people feel better on one generic than they do on another. Try to work out if you feel better on a particular generic and ensure that this is the brand given to you by the pharmacy. If one particular pharmacy does not have it in stock, try another pharmacy. Pharmacies may be purchasing whatever is cheapest at the time of ordering so you may need to insist on health grounds.
  • Some people have a lactose intolerance. Levothyroxine contains lactose. There are brands of lactose free thyroxine available on a “named patient basis” – see our “Named Patient Basis” leaflet.
    Discuss with your doctor the possibility of being prescribed lactose free thyroxine instead. Contact us for details of these medications.
  • You may not actually be on enough levothyroxine. Dr A Toft writes in the BMA book “Understanding Thyroid Disorders”, “The consensus is that enough should be given to ensure that levels of T4 in the blood are at the upper limit of normal or slightly elevated and those of TSH at the lower limit of normal, or in some patients undetectable.” He also states, “Although, by taking excessive thyroxine, a sense of well-being, increased energy and even weight loss may be achieved in the short term, there are long-term dangers to the heart and a possibility of increasing the rate of bone thinning and therefore encouraging the development of osteoporosis.
    This book is available from pharmacies, bookshops and www.amazon.co.uk
    However, there has been recent evidence to show that it may be safe for patients taking long-term thyroxine replacement therapy to have a low but not suppressed TSH level. The patients who took part in the study who had very high (more than 4.0mU/l) or suppressed (less than 0.03mU/l) TSH levels more frequently suffered from heart disease, abnormal heartbeat patterns and bone fractures compared to patients with TSH levels in the normal range (0.4-4.0). Patients who had a slightly low TSH level (0.04 – 0.4mU/l) did not have an increased risk of contracting any of these conditions.
    Take the booklet and details of the above study to your next appointment with your doctor and discuss the possibility of a further increase of levothyroxine. If you experience signs of over-replacement such as feeling very hot and sweaty, have a tremor and fast heartbeat, you should contact your doctor as soon as possible to discuss going back to your previous dosage.
  • Some people do not convert their thyroxine adequately into T3. This could be due to lack of certain vitamins and minerals or possibly due to a faulty gene. The DIO2 gene was researched in 2009 and the results were published in the paper entitled, “Common Variation in the DIO2 Gene Predicts Baseline Psychological Well-Being and Response to Combination Thyroxine Plus Triiodothyronine Therapy in Hypothyroid Patients” by V Panicker, P Saravanan, B Vaidya, J Evans, A Hattersley, T Frayling & C Dayan – jcem.endojournals.org/content/94/5/1623.full.pdf+html
    The researchers found that patients on levothyroxine (T4) alone felt worse if the faulty DIO2 gene was inherited through one parent and worse still if they inherited the faulty gene from both parents.
    The patients on this study were given T4 only for a set period and then combination treatment of both T4 and T3. The patients who had normal genes did not feel any different on combination treatment. However, those who had one faulty gene felt better on the combination treatment and those with both faulty genes felt better still.
    This means that there is a possibility that patients who are on levothyroxine alone and still have symptoms may improve with the addition of T3.
    Because this faulty gene causes a deficiency of T3 within the cells, the usual thyroid hormone function tests will not show up a problem. This means that your TSH, FT4 and FT3 blood tests will look normal.
    The researchers concluded, “Our results require replication but suggest that commonly inherited variation in the DIO2 gene is associated both with impaired baseline psychological well-being on T4 and enhanced response to combination T4/T3 therapy, but did not affect serum thyroid hormone levels.” This means that some people do not convert but this doesn’t show in their blood tests.
    Thyroid UK is now working with a laboratory that does this test – Regenerus Laboratories Ltd. For more information on the DIO2 test and how to get tested click here
  • Some people feel better taking natural desiccated thyroid (NDT). This is what was used before synthetic levothyroxine came on the market. It is available on the NHS on a normal prescription on a “named patient basis” but some medical bodies do not like patients being prescribed this even though patients may feel better on it.
    On 19th November 2008 The Royal College of Physicians, in particular its Patient and Carer Network and the Joint Specialty Committee for Endocrinology & Diabetes; The Association for Clinical Biochemistry; The Society for Endocrinology; The British Thyroid Association; The British Thyroid Foundation Patient Support Group and The British Society of Paediatric Endocrinology and Diabetes issued a statement, endorsed by the Royal College of General Practitioners, entitled “The Diagnosis and Management of Primary Hypothyroidism”. This statement was also mentioned in the BMJ Editorial entitled, “Diagnosis and treatment of primary hypothyroidism – New guidance highlights how to do it in primary care”.
    This Statement includes a statement in the “Conclusion”, “The College does not support the use of thyroid extracts or thyroxine and T3 combinations without further validated research published in peer-reviewed journals. Therefore, the inclusion of T3 in the treatment of hypothyroidism should be reserved for use by accredited endocrinologists in individual patients.”
    Dr John Lowe published a rebuttal to this Statement where he discusses various papers in respect of direct comparisons of levothyroxine and natural desiccated thyroid and which showed that the effects were similar on hypothyroid patients. One of them states, “a daily dose of 100mcg of T4 was on average equal in biologic activity to 101mg of desiccated thyroid; 60mg of desiccated thyroid was equal to 60μg of T4.”
    The article does state, “If no obvious cause is found the patient should be referred to an accredited hospital endocrinologist or general physician.” However, many doctors are unwilling to refer patients to endocrinologists for hypothyroidism.
    Thyroid UK has often heard that doctors state that “There are no studies comparing natural desiccated thyroid (NDT) with levothyroxine.” If your doctor states this, give them a copy of Dr John Lowe’s paper –
    ‘Stability, Effectiveness, and Safety of Desiccated Thyroid vs Levothyroxine’
    Thyroid UK has also often heard that doctors tell their patients, “You never know how much of each hormone is in the tablets.” This is untrue. NDT goes through the same process that levothyroxine goes through and is tested to ensure that the correct amount of T4 and T3 is in each tablet. United States Pharmacopeia (USP) is the official public standards–setting authority for all prescription and over–the–counter medicines and other healthcare products manufactured or sold in the United States. Thyroid USP state that thyroid tablets should contain not less than 90% and not more than 110% of the labelled amounts of levothyroxine and liothyronine, the labelled amounts being 38ug of levothyroxine and 9ug of liothyronine for each 65mg of the labelled content of thyroid.
    The American Food and Drug Administration (FDA) have had concerns about potency and stability in brands of levothyroxine. In October 2007, the FDA announced that it is tightening its potency specifications for all levothyroxine (sodium) to ensure the drug retains its potency over its entire shelf life. Thyroid UK wonders if this could be a problem in the UK too but it is very difficult to obtain this information.


  • The usual first treatment for hyperthyroidism is Carbimazole but some patients do not feel very well on this. Itching can be a side effect that is unbearable. If this happens to you, discuss with your doctor the possibility of trying a different drug. Propylthiouracil (PTU) is an alternative that some people find much better.
    Patients are usually kept on Carbimazole or PTU for up to 18 months before other treatment such as Radio-active Iodine (RAI) or surgery is offered. Some doctors feel that patients can actually stay on these drugs for longer than that. If you decide that you would like to wait before RAI or surgery discuss the possibility of staying on the tablets for a while longer.
  • Try to work with your doctor. Getting cross or abusive with your doctor is not helpful. If your doctor is not willing to discuss these issues with you, then perhaps it’s time to find another NHS doctor. If you cannot find an NHS doctor that will work with you and you are still ill, it might be worth visiting a private doctor (see our Private Doctors and Practitioners leaflet).

Signs Your Thyroid is Out of Whack, and How to Heal It

  • If you’re having symptoms and you think something’s up with your thyroid, or if you had some thyroid testing done and you want to understand the results, you might be confused on where to go from here.
  • Hypothyroidism symptoms include fatigue, loss of libido, hair loss, and more.
  • Hyperthyroidism symptoms include anxiety, heart palpitations, feeling hot all the time, and more.
  • Typical doctors don’t run the right tests. Find out why the testing can get confusing and what to request from your doctor.
  • Traditional thyroid treatment includes thyroid medication, surgery, or radiation. You might have some natural alternatives to explore.
  • Read on to find out what to test, how to approach treatment, and what it all means.

Until my mid-twenties, I felt like my gas pedal was all the way to the floor, and I was going slower, not faster. I was tired all the time, and doing everyday things felt like wading through a big tub of sludge.

I knew I wasn’t thinking as clearly and getting as much done as I could be. It made me feel like a failure. I wondered what was wrong with me, like I didn’t want it enough or that I should only try harder.

When I was 26, I went to an anti-aging doctor who ran a head-to-toe workup on me, which included a full thyroid panel. The tests clearly showed why I felt like crap. I didn’t have nearly enough thyroid hormone. Without it, your mitochondria, the microscopic power plants in your cells, can’t make energy. I went home with a prescription for thyroid medication.

Literally, the next day, I got my mojo back. Everything in my life felt like it took less work. I moved more quickly, I could think more clearly. The difference was like falling asleep in Kansas and waking up in technicolor Oz.

Here’s the kicker — a normal doctor would have told me my thyroid was fine. My TSH numbers were normal, and typical doctors don’t go any further than that. So, I wanted to write the guide I wish I’d had when I was falling asleep in my 12th cup of coffee of the day.

If you’re having thyroid symptoms and you think something’s up with your thyroid, or if you had some thyroid testing done and you want to understand the results, keep reading to understand where to go from here.

What does your thyroid do?

The easier question to answer is, what doesn’t the thyroid do? Your thyroid secretes hormones that regulate pretty much everything your body does, like:

  • Menstrual cycles
  • Heart function
  • Digestion
  • Mood
  • Bone density
  • Brain function
  • Metabolism

Those are only a few of them. A complete list of everything the thyroid does would have you scrolling for days. That’s why it’s so crucial that it works, and why it can ruin your life if it doesn’t. Too little thyroid hormone and it feels like your whole body is asleep and you’re carrying a sack of rocks on your back. Too much, and you feel panicky and turbocharged, not in a good way.

Thyroid symptoms

In general, you have a thyroid disorder if your thyroid makes too much or too little hormone.

Hyperthyroidism symptoms

Hyperthyroid is an overactive thyroid, when you make too much thyroid hormone. Hyperthyroid symptoms include:

  • Anxiety
  • Irritability
  • Dizziness, vertigo
  • Mental problems
  • Heart palpitations
  • Tremors
  • Feeling too hot
  • Excess sweat
  • Scant or missed periods in women
  • Infertility
  • Blurred vision
  • Weight changes (usually loss)
  • Thinning of hair
  • Itching
  • Rashes
  • Possible increase in blood sugar
  • Fatigue

Thyroid disorders that cause hyperthyroid

Your thyroid can work overtime for various reasons.

Graves’ disease. Graves’ disease is an autoimmune condition where your immune system attacks the thyroid. Instead of destroying the tissue, it binds to thyroid receptors which activates hormone production. Then, it floods your body with too much hormone.

Subacute thyroiditis. When your thyroid gland is inflamed, thyroid hormone can seep out. This form of hypothyroidism is temporary — usually, it lasts only a few weeks.

Hypothalamus and pituitary miscommunications. When the hypothalamus detects low thyroid hormone levels, it releases thyrotropin-releasing hormone (TRH), which tells the pituitary gland to release thyroid stimulating hormone (TSH). TSH then tells the thyroid to ramp up thyroid hormone production. When one of these misfires, you don’t make the right amount of thyroid hormone.

Adenomas, or nodules. When bumps develop on the thyroid, they can become active and secrete thyroid hormone. Nodules can be benign or cancerous, so if you have them, get them checked out by your functional medicine doctor.

Thyroid cancer. Thyroid cancer can cause hyperthyroidism, or it can decrease thyroid function and cause hypothyroid symptoms.

Hypothyroid is the opposite of hyperthyroid — your thyroid doesn’t make enough hormone. Hypothyroid symptoms include:

  • Weight gain
  • Hair loss
  • Dry skin
  • Dry hair that’s prone to breakage
  • Pale skin
  • Cold intolerance
  • Fatigue
  • Weakness
  • Constipation
  • Depression
  • Irritability
  • Memory problems
  • Heavy or erratic periods
  • Decreased libido

One lesser known but common symptom is that you lose the outer third of your eyebrows. I probably had thyroid problems as a kid, because I still have thin outer eyebrows.

More Articles From Dave Asprey

  • 4 Ways to Treat Hypothyroidism Naturally

Thyroid disorders that cause hypothyroid

There are several reasons why you don’t get enough thyroid hormone.

Toxic load. If your body’s detox systems like the liver and kidneys have too much to deal with, you might not be getting rid of all of the toxins you come into contact with on a daily basis. That’s when autoimmune disease develops, and sometimes, the thyroid is the target. Which brings us to…

Hashimoto’s thyroiditis. Hashimoto’s, aka lymphocytic thyroiditis, is an autoimmune disease of the thyroid, which means the immune system somehow marked the thyroid as an invader and attacks it. Tissues get damaged, and it doesn’t produce enough thyroid hormone.

Certain prescriptions. Some medications slow thyroid function. Ask your doctor or pharmacist if any medicines you take are concerning.

You no longer have a thyroid gland. If you’ve had surgery to remove the thyroid or part of it, or if your doctor killed off your thyroid with radiation because you made too much hormone, you might not make sufficient thyroid hormone or any at all.

Radiation. If you’ve had radiation treatments on or near the neck for cancer, your thyroid might have been damaged in the crossfire. That would affect how much hormone your thyroid makes.

Iodine deficiency. Your thyroid needs iodine to work properly, and you have to get it through your diet. Your doctor might tell you that iodine deficiency is rare in the US, but that’s not a reason to skip a test. Food manufacturers add iodine to things like bread, milk, packaged foods, and table salt. If you’ve adopted a diet that keeps inflammation down, you’re not eating any of those things, so you’re not getting added iodine. That’s not a reason to reach for a loaf of sandwich bread. You can get a well-sourced supplement iodine if you’re deficient and keep eating real food.

Pregnancy and postpartum. Some women experience postpartum thyroiditis, inflammation in the thyroid sometime in the first year after having a baby. Thyroid hormone production increases, then drops, causing symptoms. It’s usually temporary, but have your doc keep an eye on it.

Congenital hypothyroidism. Some people are born with a bum thyroid. Congenital hypothyroidism is when the thyroid didn’t develop properly. Most hospitals screen for it at birth.

Hypothalamus or pituitary abnormalities. Your hypothalamus releases thyrotropin-releasing hormone (TRH), which tells the pituitary gland to release thyroid stimulating hormone (TSH). When the hypothalamus doesn’t make enough TRH, your pituitary gland doesn’t release enough TSH and your thyroid doesn’t get the message to produce hormone. Or, the hangup can happen at the pituitary level, and it doesn’t release enough TSH. Either way, you need enough of both to keep everything communicating and functioning.

Thyroid tests and thyroid optimal ranges — what to expect at the doctor

Chances are, you’ve landed here and you’re reading this because you’re having a heck of a time navigating thyroid testing and diagnosis. Maybe you know something’s up, but your tests are coming back normal, or you feel like you’re not getting the full picture.

You’re not alone. If you’re going to a western medicine doctor for thyroid symptoms, you might have some back and forth, even some second or third opinions before you get the information you need.

Functional medicine and naturopathic doctors are simply better at diagnosing and treating the thyroid. The difference lies in the tests ordered and what’s considered “normal.” There are exceptions — doctors are out there who fully understand how hormone levels, blood tests, medications, and individual differences between patients all work. But, you’ll need to do some digging to find “Dr. Right,” as Bulletproof Radio podcast guest Izabella Wentz (The Thyroid Pharmacist) calls them. (iTunes)

When they’re licensed in your state, functional medicine and naturopathic doctors can order all of the blood tests and prescriptions you might need, and they’re likely to incorporate non-medical interventions as well.

A lot of docs will use TSH only as in the indicator of your thyroid function. If that’s the case, you might want to go doctor shopping.

Here are the thyroid tests that will give you the full picture of how everything’s working:

  • TSH
  • Free T4
  • Free T3
  • Reverse T3
  • Thyroid Peroxidase Antibodies (TPOAb)
  • Thyroglobulin Antibodies (TgAb)

More Articles From Dave Asprey

  • 4 Ways to Treat Hypothyroidism Naturally

TSH – Thyroid Stimulating Hormone

TSH is the hormone that tells your thyroid to make more thyroid hormone. Here’s how it works.

Your hypothalamus is like the thermostat for thyroid hormone — it keeps watch on how much thyroid hormone is in your bloodstream, and it responds when you need more. When your level drops too low, it releases TRH, thyroid releasing hormone. Your pituitary gland picks up on TRH, and it releases TSH in response.

Does it test thyroid function? Well, yes, but only if your hypothalamus and pituitary are doing their thing. The stops on the signaling pathway can get messed up for various reasons. Any problems with detecting hormone or releasing hormone at any point in the cascade, and the TSH test becomes worthless.

TSH Optimal range: 0.5-2 IU/L

High TSH
High TSH indicates you’re hypothyroid. Since it’s a signaling hormone, high TSH indicates that your body detects low hormone, so it’s turning up the volume on the signal to make more. If your thyroid isn’t or cannot respond because it’s compromised in some way, you’ll produce more and more TSH. This number can really go off the charts, depending on how low you are and how long you’ve been hypothyroid.

Low TSH tells you that you have too much thyroid hormone, or that you can cut your dose of thyroid medication, so it indicates hyperthyroid. Certain thyroid medications can suppress your TSH, so if you don’t have symptoms you’re still in good shape.

Normal TSH
On one hand, normal TSH could mean that your thyroid is fine. On the other hand, you can have a normal number for TSH and still have an abnormal thyroid. One lab’s normal differs from the next, one doctor’s optimal ranges differ from the next. You can’t rely on TSH alone to tell how your thyroid is doing, especially if you have symptoms.

Free T4 – Thyroxine

Your thyroid makes mostly T4, also known as thyroxine. Thyroxine is the storage form of thyroid hormone — it circulates in the bloodstream, then your tissues snap it up and store it. When an area of your body needs a power boost, it gets converted into the active form, T3 (more on that in a minute). Most of it is bound to protein in the blood, but free T4 is unbound and available for your body to use.

Optimal Free T4 range: 15-23 pmol/L

High Free T4 indicates hyperthyroidism.
Low Free T4 indicates hypothyroidism.

T3 – Triiodothyronine

When your tissues determine they need a power-up, they convert T4 into Free T3, the active form of thyroid hormone. Sometimes your thyroid makes sufficient hormone, but you don’t convert it, so you’ll get hypothyroid symptoms.

Optimal Free T3 range: > 5-7 pmol/L

High Free T3 indicates hyperthyroidism
Low Free T3 might explain hypothyroid symptoms. If your Free T4 is fine and your Free T3 is low, you might have trouble converting T4 to T3.

Reverse T3

Some of your T4 stores convert to Reverse T3. While T3 helps your cells make energy, Reverse T3 slows down T3 and slows down energy production. You might think more energy is better, but if your cells make too much energy, you end up with hyperthyroid symptoms like racing heart and anxiety.

Optimal reverse T3 range: 11-18 ng/dl

High Reverse T3 might explain hypothyroid symptoms. A high number indicates your body is using too much T4 to make Reverse T3, and not making enough Free T3 that your cells use to make energy.

Low Reverse T3 might explain hyperthyroid symptoms. If you don’t have enough of it and your other thyroid hormones are within range, your cells are making too much energy and you feel it — not in a good way.

Thyroid Antibodies — TPOAb and TgAb

TPOAb — Thyroid Peroxidase Antibodies Thyroid peroxidase antibodies attack the enzyme used to make thyroid hormone.

TgAb — Thyroglobulin Antibodies Thyroglobulin antibodies attack thyroglobulin, which your thyroid uses to make hormone.

If either or both of these antibodies test high, that means your immune system attacks the thyroid. That means you have one of two autoimmune thyroid diseases — Hashimoto’s thyroiditis if you’re hypothyroid, and Graves’ disease if you’re hyperthyroid.

Optimal thyroid antibodies range (either TPOAb or TgAb): < 2 IU/m

Your thyroid uses iodine to make thyroid hormones. If you don’t have enough, you don’t make enough hormone, and you’ll have hypothyroid symptoms.

Your doctor will probably tell you that iodine deficiency is rare. That might have been true when everyone was eating white sandwich bread and conventional iodized salt. If you’re eating a real-food diet that keeps inflammation down, you’re probably not getting iodine that food manufacturers put into foods.

There are a few ways to test. One way to test at home is to draw a 2 inch square on your forearm with a non-toxic pen, and “paint” on a 2% iodine solution. Be careful not to wash it off! If it fades before the 24-hour mark, ask your doctor to test your iodine levels.

You can only know for sure if a lab measures your levels. If you’re getting tests done anyway, ask to tack on the iodine test.

Iodine Optimal iodine levels — >100 µg/L (urine test)

If you’re low and you do supplement, make sure the supplement you choose is a high-quality kelp iodine supplement that comes from waters with low levels of heavy metals.

Thyroid medication and treatment

Hypothyroid medication and treatment

When I found out I had Hashimoto’s, I had to go on thyroid medication to get enough thyroid hormone. The most common medication that doctors prescribe for hypothyroid is Synthroid, which contains T4 only. Other T4 only medications include Tirosint and Levoxyl. That will work for you if you’re converting T4 to T3, but it won’t do a thing for you if you if your problem lies with conversion.

People with conversion problems will feel better on combination T4/T3 medications like Nature-Throid, Armour, or a custom-compounded formula.

Less commonly, doctors will prescribe a T3-only thyroid medication, like Cytomel.

Hyperthyroid medication and treatment

When you have too much thyroid hormone, there are a few ways to tackle it.

Anti-thyroid medication. Anti-thyroid medication keeps your thyroid from making hormone.

Radioactive iodine. The thyroid absorbs iodine, but the rest of the body doesn’t. So, by using radioactive iodine, you can selectively damage thyroid cells with radiation, and prevent them from making hormone. The damage is permanent. The risk is going overboard, causing an underactive thyroid and requiring a lifetime of thyroid medication.

Surgery. You can get all or part of the thyroid gland removed. Or, the surgeon could remove an active nodule that secretes hormone.

On an episode of Bulletproof Radio (iTunes), I talked with thyroid expert Dr. Izabella Wentz, PharmD, about her protocol. She focuses on building the body’s natural resilience by zeroing in on natural defense systems, like the liver.

“I started thinking about what are the fundamentals of healing for each person. What are the things that just about everybody can do to make themselves feel better regardless of what their root cause is, because every Hashimoto’s patient is like a snowflake, everybody’s got a slightly different story. But supporting our own body’s natural protective defenses, supporting the liver, helps to build resilience, because now, we’re no longer toxic to everything.”

Getting your body working properly might help your thyroid work again, or lessen your medication.

When I went on SARMs, I started getting hyperthyroid symptoms, so I went off of my medication. After a few months, I noticed low-thyroid symptoms like brittle hair and hair loss, so I went back on but I adjusted my dose. With the extra muscle mass, I had more mitochondria, so I was making enough energy to avoid the energy dips, but I still didn’t have enough thyroid hormone. Any doctor would tell you that there’s no moral victory for going off of thyroid medication if you need it.

Okay, I threw a lot of info at you. The point is not for you to become a thyroid expert. Instead, use this information to have an informed conversation with your doctor about your symptoms, your testing, and how it all fits together.

The most common thyroid story I hear is the one where a person was in and out of the doctor’s office several times before someone finally pinpointed the right testing and treatment plan. Having a basic understanding can help you ask the right questions and better yet, find the right doctor who understands what you’re going through and how to approach it.

Hypothyroidism (Underactive Thyroid)

On this page:

  • What is hypothyroidism?
  • How common is hypothyroidism
  • Who is more likely to develop hypothyroidism?
  • Is hypothyroidism during pregnancy a problem?
  • What other health problems could I have because of hypothyroidism?
  • What are the symptoms of hypothyroidism?
  • What causes hypothyroidism?
  • How do doctors diagnose hypothyroidism?
  • How is hypothyroidism treated?
  • What should I eat or avoid eating if I have hypothyroidism?

What is hypothyroidism?

Hypothyroidism, also called underactive thyroid, is when the thyroid gland doesn’t make enough thyroid hormones to meet your body’s needs. The thyroid is a small, butterfly-shaped gland in the front of your neck. Thyroid hormones control the way the body uses energy, so they affect nearly every organ in your body, even the way your heart beats. Without enough thyroid hormones, many of your body’s functions slow down.

The thyroid is a small gland in your neck that makes thyroid hormones.

How common is hypothyroidism?

About 4.6 percent of the U.S. population ages 12 and older has hypothyroidism, although most cases are mild.1 That’s almost 5 people out of 100.

Who is more likely to develop hypothyroidism?

Women are much more likely than men to develop hypothyroidism. The disease is also more common among people older than age 60.1

You are more likely to have hypothyroidism if you

  • have had a thyroid problem before, such as a goiter
  • have had surgery to correct a thyroid problem
  • have received radiation treatment to the thyroid, neck, or chest
  • have a family history of thyroid disease
  • were pregnant in the past 6 months
  • have Turner syndrome, a genetic disorder that affects females
  • have other health problems, including
    • Sjögren’s syndrome, a disease that causes dry eyes and mouth
    • pernicious anemia, a condition caused by a vitamin B12 deficiency
    • type 1 diabetes
    • rheumatoid arthritis, an autoimmune disease that affects the joints
    • lupus, a chronic inflammatory condition

Is hypothyroidism during pregnancy a problem?

Hypothyroidism that isn’t treated can affect both the mother and the baby. However, thyroid medicines can help prevent problems and are safe to take during pregnancy. Learn more about causes, diagnosis, and treatment of hypothyroidism during pregnancy.

What other health problems could I have because of hypothyroidism?

Hypothyroidism can contribute to high cholesterol, so people with high cholesterol should be tested for hypothyroidism. Rarely, severe, untreated hypothyroidism may lead to myxedema coma, an extreme form of hypothyroidism in which the body’s functions slow to the point that it becomes life threatening. Myxedema coma requires immediate medical treatment.

What are the symptoms of hypothyroidism?

Hypothyroidism has many symptoms that can vary from person to person. Some common symptoms of hypothyroidism include

  • fatigue
  • weight gain
  • a puffy face
  • trouble tolerating cold
  • joint and muscle pain
  • constipation
  • dry skin
  • dry, thinning hair
  • decreased sweating
  • heavy or irregular menstrual periods
  • fertility problems
  • depression
  • slowed heart rate
  • goiter

Because hypothyroidism develops slowly, many people don’t notice symptoms of the disease for months or even years.

Many of these symptoms, especially fatigue and weight gain, are common and don’t always mean that someone has a thyroid problem.

What causes hypothyroidism?

Hypothyroidism has several causes, including

  • Hashimoto’s disease
  • thyroiditis, or inflammation of the thyroid
  • congenital hypothyroidism, or hypothyroidism that is present at birth
  • surgical removal of part or all of the thyroid
  • radiation treatment of the thyroid
  • some medicines

Less often, hypothyroidism is caused by too much or too little iodine in the diet or by pituitary disease.

Hashimoto’s Disease

Hashimoto’s disease is the most common cause of hypothyroidism. Hashimoto’s disease is an autoimmune disorder. With this disease, your immune system attacks the thyroid. The thyroid becomes inflamed and can’t make enough thyroid hormones.


Thyroiditis is inflammation of your thyroid that causes stored thyroid hormone to leak out of your thyroid gland. At first, the leakage increases hormone levels in the blood, leading to hyperthyroidism, a condition in which thyroid hormone levels are too high. The hyperthyroidism may last for up to 3 months, after which your thyroid may become underactive. The resulting hypothyroidism usually lasts 12 to 18 months, but sometimes is permanent.

Several types of thyroiditis can cause hyperthyroidism and then cause hypothyroidism:

  • Subacute thyroiditis. This condition involves a painfully inflamed and enlarged thyroid. Experts are not sure what causes subacute thyroiditis, but it may be related to an infection caused by a virus or bacteria.
  • Postpartum thyroiditis. This type of thyroiditis develops after a woman gives birth.
  • Silent thyroiditis. This type of thyroiditis is called “silent” because it is painless, even though your thyroid may be enlarged. Experts think silent thyroiditis is probably an autoimmune condition.

Congenital hypothyroidism

Some babies are born with a thyroid that is not fully developed or does not function properly. If untreated, congenital hypothyroidism can lead to intellectual disability and growth failure—when a baby doesn’t grow as expected. Early treatment can prevent these problems, which is why most newborns in the United States are tested for hypothyroidism.

Surgical removal of part or all of the thyroid

When surgeons remove part of the thyroid, the remaining part may produce normal amounts of thyroid hormone, but some people who have this surgery develop hypothyroidism. Removal of the entire thyroid always results in hypothyroidism.

Surgeons may remove part or all of the thyroid as a treatment for

  • hyperthyroidism
  • a large goiter
  • thyroid nodules, which are noncancerous tumors or lumps in the thyroid that can produce too much thyroid hormone
  • thyroid cancer

Radiation treatment of the thyroid

Radioactive iodine, a common treatment for hyperthyroidism, gradually destroys the cells of the thyroid. Most people who receive radioactive iodine treatment eventually develop hypothyroidism. Doctors treat people with head or neck cancers with radiation, which can also damage the thyroid.


Some medicines can interfere with thyroid hormone production and lead to hypothyroidism, including

  • amiodarone, a heart medicine
  • interferon alpha, a cancer medicine
  • lithium, a bipolar disorder medicine
  • interleukin-2, a kidney cancer medicine

How do doctors diagnose hypothyroidism?

Your doctor will take a medical history and do a physical exam, but also will need to do some tests to confirm a diagnosis of hypothyroidism. Many symptoms of hypothyroidism are the same as those of other diseases, so doctors usually can’t diagnose hyperthyroidism based on symptoms alone.

Because hypothyroidism can cause fertility problems, women who have trouble getting pregnant often get tested for thyroid problems.

Your doctor may use several blood tests to confirm a diagnosis of hypothyroidism and find its cause. Learn more about thyroid tests and what the results mean.

How is hypothyroidism treated?

Hypothyroidism is treated by replacing the hormone that your own thyroid can no longer make. You will take levothyroxine, a thyroid hormone medicine that is identical to a hormone the thyroid normally makes. Your doctor may recommend taking the medicine in the morning before eating.

Your doctor will give you a blood test about 6 to 8 weeks after you begin taking thyroid hormone and adjust your dose if needed. Each time your dose is adjusted, you’ll have another blood test. Once you’ve reached a dose that’s working for you, your health care provider will probably repeat the blood test in 6 months and then once a year.

Your hypothyroidism most likely can be completely controlled with thyroid hormone medicine, as long as you take the recommended dose as instructed. Never stop taking your medicine without talking with your health care provider first.

What should I eat or avoid eating if I have hypothyroidism?

The thyroid uses iodine to make thyroid hormones. However, people with Hashimoto’s disease or other types of autoimmune thyroid disorders may be sensitive to harmful side effects from iodine. Eating foods that have large amounts of iodine—such as kelp, dulse, or other kinds of seaweed—may cause or worsen hypothyroidism. Taking iodine supplements can have the same effect.

Talk with members of your health care team about what foods you should limit or avoid, and let them know if you take iodine supplements. Also, share information about any cough syrups that you take because they may contain iodine.

Women need more iodine when they are pregnant because the baby gets iodine from the mother’s diet. If you are pregnant, talk with your health care provider about how much iodine you need.

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