Thyroid physiology is complex. The thyroid is part of the endocrine system. The pituitary produces a hormone called thyroid stimulating hormone (TSH) which stimulates the thyroid to produce thyroxine (T4). Thyroxine is inactive and needs to be converted by the tissues and organs of the body into the active hormone, tri-iodothyronine (T3).
There are mainly two types of thyroid disease – hypothyroidism and hyperthyroidism. This article includes lots of questions we have been asked over the years but if your question is not here, do let us know – enquiries@thyroiduk.org
Hypothyroidism is the term given when the thyroid produces less thyroid hormone than it should. Other names for this are myxoedema or an underactive thyroid.
Hypothyroidism results from the failure of sufficient thyroid hormone reaching the tissues to control metabolism, which it does by governing the passage of nutrients across the cell membrane and controlling the activity of the mitochondrion, which produces energy within the cell.
There is also a condition known as subclinical hypothyroidism which is the term used when patients have symptoms of hypothyroidism but only the TSH is abnormal.
There are two causes of hypothyroidism:
Primary hypothyroidism - which is caused by problems with the thyroid gland such as:
Secondary hypothyroidism - which is caused by problems outside of the thyroid gland:
The incidence of (overt) hypothyroidism is 2% women and 0.2% men. The incidence of subclinical hypothyroidism is 6-8% women and 3% men. The incidence of pregnant women who will develop hypothyroidism is 2.5%.
Hypothyroidism is most common in women of around 60 years of age and symptoms are often ignored during the early stages by both patients and doctors.
Signs and symptoms of hypothyroidism can come on very slowly over a period of time. These include:
Hypothyroidism is diagnosed by blood tests and sometimes an examination of the thyroid area of the neck. The tests available to diagnose thyroid disease are:
However, depending on where you live in the UK the TSH test is often the only test performed by doctors, which means there is a possibility that Hashimoto’s and secondary hypothyroidism may be missed.
A TSH level above the reference range will usually give a diagnosis of hypothyroidism. Some doctors will accept a TSH level above the top of the range (which is usually around 0.4 – 4.5 or thereabouts) along with symptoms of hypothyroidism but some, as per guidance, will wait until the level of TSH is above 10.0 before treatment is offered.
If thyroid peroxidase antibodies are present, subclinical hypothyroidism carries a greater risk of progression to overt hypothyroidism.
Subclinical hypothyroidism is diagnosed when the patient has TSH levels above the range with normal FT4 levels. Research has shown that symptoms of subclinical hypothyroidism improved with treatment.
Unfortunately, the DIO1 and DIO2 genetic testing is not available on the NHS but are available from Regenerus Laboratories via our order form.
First of all, make sure you know your exact test results including the ranges as ranges are different across the country and can change over time.
Keep a note of all your test results in a notebook so that you can see if, for instance, your TSH is going up or down.
TSH reduces from 9am and again in the afternoon so always make sure that you have your test done at the same time of day (preferably first thing in the morning) as your level may change for this reason.
Ask your doctor to test for FT4 and thyroid antibodies as well as TSH as you may have subclinical hypothyroidism/Hashimoto’s disease. Some areas will do this, some won’t. Unfortunately, T3 is rarely tested now by your GP and if it is, the laboratory will probably not do the test.
If your TSH is borderline (near the edge of the top of the range or just a little over) NICE state:
“Consider a 6-month trial of levothyroxine for adults under 65 with subclinical hypothyroidism who have:
If symptoms do not improve after starting levothyroxine, re-measure TSH and if the level remains raised, adjust the dose.”
To see the full NICE guidance it can be downloaded here:
If you can’t get these tests done on the NHS, you need to think about whether it is worth paying for private testing. We work with various testing companies if you decide to do this. We have organised discounts with some of the companies if you use our code - https://thyroiduk.org/testing/private-thyroid-tests-in-the-uk/
We have a Position Statement on the Use of Private Testing which you can find here - https://thyroiduk.org/testing/our-view-on-private-testing/
You need to ensure that your vitamin and mineral status have also been checked in case of deficiency such as vitamin B12 (the symptoms are very similar); vitamin D; iron; ferritin; zinc and selenium.
Vitamin and mineral deficiency can play a part in thyroid disease so it’s important that you get these checked.
As in the previous question, first of all, make sure you know your exact test results, including the ranges, as ranges are different across the country.
Keep a note of all your test results in a notebook so that you can see if, for instance, your TSH is going up or down.
TSH reduces from 9am and again in the afternoon so always make sure that you always have your test done at the same time of day (preferably first thing in the morning) as your level may change for this reason.
Ask your doctor to test for FT4 and thyroid antibodies as well as TSH as you may have Hashimoto’s disease. Some areas will do this, some won’t.
If your TSH is borderline (near the edge of the top of the range or just a little over) NICE state:
“Consider a 6-month trial of levothyroxine for adults under 65 with subclinical hypothyroidism who have:
If symptoms do not improve after starting levothyroxine, re-measure TSH and if the level remains raised, adjust the dose.”
To see the full NICE guidance it can be downloaded here:
If you can’t get these tests done on the NHS, you need to think about whether it is worth paying for private testing. We work with various testing companies if you decide to do this. We have organised discounts with some of the companies if you use our code - https://thyroiduk.org/testing/private-thyroid-tests-in-the-uk/
You also really need to ensure that your vitamin and mineral status have also been checked in case of deficiency such as vitamin B12 (the symptoms are very similar); vitamin D; iron; ferritin; zinc and selenium.
Vitamin and mineral deficiency can play a part in thyroid disease so it’s important that you get these checked.
Biotin (vitamin B7) can give falsely high FT4 results so you should stop taking biotin a few days before you have your next thyroid test done.
Levothyroxine – this is the most common treatment for hypothyroidism. This replaces the thyroxine that the thyroid gland is not producing. Most people feel better on this medication. However, some 5 - 10% of patients continue to have symptoms on levothyroxine.
Liothyronine - this is a treatment that replaces the T3 (tri-iodothyronine) in your body in cases where there is a lack of conversion of levothyroxine to T3. It needs to be taken in addition to your levothyroxine although a few patients take it without levothyroxine.
Although the addition of liothyronine to levothyroxine has been studied in patients, the results have been inconclusive. In some of the studies patients say they preferred it. However, there has been no overall objective evidence of benefit in terms of symptom scores or other physiological markers although it is possible that the patients included in the trial did not need T3 in the first place and therefore the results may be skewed.
There was some research that showed that patients with the DIO2 gene had worse General Health Questionnaire (GHQ) scores than those without the gene and improved on liothyronine.
There are guidelines on the use of levothyroxine plus liothyronine to help clinicians who want to give a trial of liothyronine to patients who remain ill on levothyroxine.
Liothyronine can now only be prescribed by an endocrinologist which is making things difficult for patients for various reasons:
Always read the guidelines before you visit your clinician with a request to have a trial of liothyronine so that you are well informed and able to discuss fully with them.
Natural desiccated thyroid (NDT) – this is a treatment that was used before the manufacture of levothyroxine and liothyronine. NDT is manufactured from pigs’ glands and contains T3 at a level higher than the level of a human being. Research has shown that some patients do very well on this treatment but it is not available on the NHS at the moment.
NDT is not a licensed drug. It is a “grandfathered” drug which is the term used for drugs that were manufactured before licensing came into being. However, it is approved in the United States of America and Canada.
NDT comes in grains with some brands containing 60mg of thyroid hormone and some containing 65mg).
Generally, 1 grain is approximately equivalent to 100mcg of levothyroxine so if you are swapping from levothyroxine to NDT your doctor will need to work out the equivalent for the amount of levothyroxine you are on/you need.
NDT contains 38mcg T4 and 9mcg T3 which is more T3 than a human thyroid would produce. The dosages come in half grains, 1 grain, 2 grains, 3 grains and 4 grains.
You can download the Prescribing Information here.
If you are lucky enough to obtain an NHS prescription you will need to find a pharmacy that can provide NDT for you. We have a list of Pharmacies and Wholesale Pharmacies if your usual pharmacy cannot obtain this for you.
For more information go to: https://www.armourthyroid.com/about-armour-thyroid
The usual starting dose of levothyroxine is 25-50mcg depending on your levels. It should also be dependent on your weight but this is not always the case.
It takes a little while for the levothyroxine to take effect. You should be tested again 6-8 weeks after the initial dosage to see if you need an increase in dosage. Again, this will depend on your levels.
The British Thyroid Association in their consensus statement state, “In those with established overt hypothyroidism, levothyroxine doses should be optimised aiming for a TSH in the 0.3–2.0 mU/L range for 3 to 6 months before a therapeutic response can be assessed. In some patients, it may be acceptable to have serum TSH below reference range (e.g. 0.1–0.3 mU/L), but not fully suppressed in the long term” so do ensure that if you still have symptoms, check where your TSH level is.
If your TSH is not below 2.0 mU/L discuss with your GP another increase in dosage.
The average dose is 100 – 150mcg but some people need less and some people need more.
It is best to take your medication first thing in the morning with a drink of water on an empty stomach. Don’t eat for at least half an hour to an hour if you can as food can stop absorption of thyroid hormone by up to 40%.
If taking your levothyroxine in the morning is a problem for you, you could try taking it just before bedtime as long as you haven’t eaten for at least half an hour to an hour to see if this works for you.
Getting better from hypothyroidism is no quick fix – it’s not like taking ibuprofen and feeling better after half an hour.
Depending on how high your TSH was, it can take many months to get better.
Yes, there are some foods that can cause issues such as malabsorption of your levothyroxine and possibly other thyroid medications:
Goitrogenic foods - such as brussel sprouts, rutabaga, turnips, cauliflower, cabbage, almonds, peanuts, walnuts, sweet corn, sorghum and millet can act like an antithyroid drug in disabling the thyroid function. They contain chemicals, which prevent the thyroid from taking in enough iodine. Eat these in moderation if you are taking thyroid hormone replacement.
Soya - there is still debate over whether soya interferes with absorption of levothyroxine. Some studies have shown no effect and some have shown an effect on women. Therefore, it may be prudent to not eat soya near the taking of your levothyroxine. Leaving a gap of four hours should ensure that it doesn’t interfere with your medication.
Fibre - high fibre diet can affect absorption. If you have always had a high fibre diet, carry on as usual.
If you are on thyroid replacement and you decide to try a high fibre diet, then your absorption may be affected and you need to have another test done about 6-8 weeks into your new regime to check to see if your levels change. You need to be consistent. Don’t do high fibre for a couple of weeks and then change back, as your levels may change with it.
Iodine/kelp - Kelp comes from seaweed and is naturally high in iodine. Kelp can therefore interfere with thyroid function. Although iodine is needed to make thyroxine and causes problems if you are deficient, those who are not deficient have no need to take it. If you take more iodine than you need it can cause problems for the thyroid such as overactivity. It can also have the opposite effect and make you more hypothyroid.
Coffee - this can interfere with absorption of levothyroxine so do not take your levothyroxine at the same time as drinking coffee – it’s probably best to wait at least an hour before partaking in your morning cup of coffee.
Tea – black tea and green tea contain fluoride that could occur either naturally in the environment or can be industrialized and added artificially to public drinking water.
Animal studies have shown reductions in T3 and T4 levels due to fluoride exposure, even at low doses but human studies have not shown this.
If you have always drunk tea before you were diagnosed it’s probably safe to assume that you can continue once on treatment. However, if you start to drink a lot of tea and notice a marked difference in your thyroid levels you may need to think about reducing the amount of tea you drink.
Levothyroxine can affect how other medicines work, so their doses may need to be changed. These medicines include insulin or tablets for diabetes and warfarin, used to prevent blood clots. Make sure you discuss this with your clinician.
Iron and calcium can affect absorption of levothyroxine. Don’t take iron supplements or calcium supplements within four hours of your medication. Don’t forget that milk contains calcium and some fruit juices are calcium fortified.
There are several medications that can interfere with thyroid medication. One most commonly used is antacids. Most of these contain aluminium hydroxide and are well known for reducing the body’s ability to absorb thyroxine. They should be taken at least two hours apart from your thyroid hormone.
We have a long list on our website.
We are told that it is possible that some people will have some thyroid antibodies without thyroid disease.
However, the antibodies can increase over time and, in many cases, people go on to become subclinical and then to have full blown hypothyroidism.
If you have thyroid antibodies along with symptoms of hypothyroidism it is possible that you do have the beginnings of thyroid disease so do keep an eye on your symptoms and levels.
Some people still have symptoms when they are on levothyroxine. This can be due to many things. It can be that you are not on enough levothyroxine. Thyroxine should be given according to weight, so the bigger you are, the more you should have. In reality, this does not happen.
Each doctor seems to have his own ideas about the highest level he will allow his patient to be in the range. However, the British Thyroid Association state in their consensus statement that some patients may need to go right to the bottom of the range as long as the TSH is not fully suppressed.
Another reason many people still feel ill on thyroxine is that they are not converting the thyroxine into T3 (tri-iodothyronine). This conversion takes place outside of the thyroid, mainly in the liver, so if the patient has some kind of problem with the liver or any of the other places where conversion takes place, then there may be a problem.
Certain vitamins, especially those of the B group and some minerals are also necessary to aid conversion, namely: iron, selenium, magnesium and zinc. If you are deficient in any of these then conversion may be less effective. If this is your problem, and supplementing with the missing vitamins and minerals doesn’t help, then you will need to consider asking your GP for a referral to an endocrinologist so that your FT3 levels can be checked (or alternatively have some private testing done).
Lastly, there seem to be a lot of people who just cannot tolerate the synthetic form of thyroxine and fare much better on the natural form which contains all four thyroid hormones including T3 (many doctors feel that T2 has a much more important part to play than we realise).
Some people cannot tolerate the ingredients (excipients) in the levothyroxine tablets. Lactose is a common reason for side effects in some people. In some brands mannitol has replaced lactose but this has caused side effects for a lot of people. Other ingredients that can cause issues for people are anhydrous levothyroxine, acacia and magnesium stearate.
If you think you are having side effects from one of the ingredients, try asking your pharmacist for a different brand that doesn’t have that particular ingredient in it.
If this works for you try asking your GP if they will name the brand on your prescription. Some GPs are able to do this and some aren’t.
There is also the possibility of obtaining levothyroxine in gelatine capsules for those severely affected but this is more expensive so your GP may not be able to prescribe them.
For more information read our article, Medications for Hypothyroidism.
There is no evidence that thyroid disease is hereditary but it can run in families if it is autoimmune. Not every child of a mother with Hashimoto’s disease will go on to have thyroid disease though.
It is possible that one sibling can have Hashimoto’s disease and another Graves’ disease. Also, an aunt could have thyroid disease but no-one in your direct family.
There may be environmental factors such as infections, life stress, iodine intake, smoking, medications such as amiodarone and interferon, radiation, and environmental toxicants that could cause thyroid disease.
Yes, we do. Bear in mind, though, that once you start seeing a private doctor and getting treated by them, you won’t be able to move your treatment over to the NHS (unless your private doctor is also an NHS doctor and he agrees to do this). You will then be paying for your treatment for the rest of your life as hypothyroidism is a lifelong condition. To obtain the list go to: https://thyroiduk.org/contact-us/get-list-of-private-gps-practitioners/
We have a list of NHS and private endocrinologists. Some of the private endocrinologists have treated some patients with T3 when they were placed on the list. It is doubtful you would find an NHS endocrinologist who would treat with NDT. It’s best to contact their secretary to check before making an appointment.
We have a Support Network which includes people who hold groups and people who are at the end of a telephone. You can contact us for our list of Support Networkers here.
We have an online community on HealthUnlocked where you can get support and have your questions answered by people who have been or who are in a similar situation to yourself. You can find it here: www.healthunlocked.com/thyroiduk
Yes, you can. We work with several testing companies and an NHS laboratory where you can obtain various private tests - https://thyroiduk.org/testing/private-thyroid-tests-in-the-uk/
We have organised discounts with some of the companies.
The TSH test (thyroid stimulating test) is an indirect test to check whether your thyroid is working properly.
TSH is a hormone produced by the pituitary gland that stimulates the thyroid gland to release thyroid hormones. This test can help diagnose thyroid disorders like hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid).
However, we believe that people should also have an FT4 test. This measures the amount of thyroxine in the blood and if both the TSH and the FT4 test are done together it will show more clearly whether your thyroid is working properly.
Another test Thyroid UK believes should be done as a first test is the thyroid peroxidase antibody test (TPO) as this will show whether you have an autoimmune form of hypothyroidism. If you have a high TPO level, the chances are that you will become hypothyroid at some point.
If you are already on levothyroxine and you are still having symptoms, after other conditions have been ruled out e.g. B12 deficiency and vitamin D deficiency, an FT3 test will check to ensure that you are converting your levothyroxine into T3 (tri-iodothyronine) properly.
Generally, it’s best to make sure that you eat healthily and have a varied diet to make sure that you have plenty of vitamins and minerals in your diet.
Your thyroid needs iron to make thyroid hormone. Vitamin D has been directly connected to autoimmune thyroid disease. Evidence also suggests that vitamin D can play a role in reducing the occurrence of other autoimmune diseases. It is therefore recommended that patients suffering from hypothyroidism are tested for vitamin D deficiency to establish if vitamin D supplementation could help.
People in the UK should take a vitamin D supplement throughout the winter but if you work inside all the time and don’t get out in the sunshine much, you might need to test to ensure that you have enough vitamin D.
Selenium is needed for the conversion of thyroxine/levothyroxine to T3. Selenium testing is not very accurate but eating two Brazil nuts per day should be enough to ensure that you are getting enough selenium.
There may be difficulties conceiving if you are hypothyroid, especially if you have Hashimoto’s disease. Make sure you visit your doctor to discuss getting pregnant. Your doctor can do some thyroid testing for you. You will need to ensure that your TSH level is below 2.5 to be sure that you can conceive (although this varies depending on which article/research you read).
NICE state, “Arrange a referral to an endocrinology specialist for all women with overt or subclinical hypothyroidism who are planning a pregnancy - https://cks.nice.org.uk/topics/hypothyroidism/management/preconception-or-pregnant/
You need to contact your doctor as soon as you know you are pregnant so that they can test your thyroid levels. Make sure that you put this in your preconception plan.
You will need more levothyroxine during pregnancy and this needs to happen as early as possible to reduce the chance of any complications for yourself and your baby.
You should aim for a TSH of less than 2.5 in the first trimester and less than 3.0 after that. It is generally recommended that your levothyroxine is increased by 25 – 50mcg per day.
You should ensure that your thyroid is tested every 5-6 weeks throughout the pregnancy. You will usually be tested again a few weeks after the baby is born.
You may be able to reduce your dosage after pregnancy but some women need to remain on a higher dose for a while.
For more information go to https://thyroiduk.org/having-a-baby/
Unfortunately, you don’t have a legal right to a second opinion. However, in most cases a clinician will consider your circumstances and whether a second opinion is needed.
It would be beneficial, though, to ask your doctor to go through everything with you and explain that you would like a second opinion. Taking another person with you for this appointment can be a good idea.
If you have hypothyroidism, you are exempt from paying for your prescriptions and therefore get them free.
You need to have a specified medical condition and have a valid medical exemption certificate (MedEx) which you can get from your GP. Hypothyroidism is on the list of specified medical conditions but hyperthyroidism is not.
For more information go to:
https://thyroiduk.org/get-support/nhs-prescriptions/free-or-low-cost-prescriptions/
If your hypothyroidism is mild e.g. borderline, and is caused by nutritional deficiencies or gut issues then ensuring that you start to eat a healthy diet full of vitamin and mineral-rich foods may improve your thyroid levels.
However, if you have overt hypothyroidism due to Hashimoto’s disease, it is doubtful that this can be improved without levothyroxine.
Thyroid UK needs funds to keep going and to support people with thyroid disease and related conditions
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Date created: 02.08.25 (V1.1)
Review date: 22.4.28
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