Thyroid Tests

Early detection of thyroid dysfunction gives you greater chances for faster recovery!

Below I’m going to share with you key thyroid tests to run to check your thyroid. Plus functional medicine optimal ranges for those thyroid tests: TSH, FT4, FT3, anti-TPO, anti-TG and reverse T3

best supplements for hashimoto's natural treatment

In this article:

Understanding Thyroid Blood Tests

You have two options – either home thyroid tests (finger prick) or a more comprehensive full thyroid panel. Thyroid home test is the fastest way to get a pretty good idea of your thyroid health however it doesn’t include two important markers: reverse t3 and insulin (especially important in terms of hypothyroid related weight gain).

On the other hand, the advanced thyroid blood test gives you a better insight and understanding of what’s going on with your thyroid, especially in terms of what is causing your thyroid issues.

How FLOWell Nutrition Can Help You Interpret Your Results

The appropriate interpretation of your thyroid blood tests will help you find the root cause of your thyroid problems and all related symptoms like weight gain, low energy and hair loss. You can read more here about early signs and symptoms of thyroid disease. Sometimes it takes years to develop thyroid conditions so the quicker you you spot it the better. The best assessment of your thyroid condition is a combination of your symptoms and your blood test results.

Best thyroid home test provider in UK

Let’s start with the more convenient option which is home thyroid blood test. It’s very simply to do and the fastest way to get results. All you need to do is order thyroid home test kit, collect finger prick blood sample and send it back using the return label. My favourite provider in UK is Medichecks.

Thyroid Home Test (with thyroid antibodies and vitamins) – from thyroid home tests this is my to go test as it TSH, free T4, free T3, thyroid antibodes and on top of that it covers vitamin D, ferritin, B12 and folate. All important for thyroid health and it the whole test costs only £86. This test is also good for early detection of subclinical hypothyroidism and the results are available very quickly – usually within 2 working days. The only drawback of home tests is that the blood can clot during the transport so sometimes you need to repeaBt the test.

Basic Thyroid Home Test (TSH, free T4 and free T3) – the most basic test (£45). It does not include thyroid antibodies. If you have never checked thyroid antibodies and really want to get your thyroid health back I would strongly recommend to do thyroid antibodies as well as this will allow you to rule auto-immune condition like Hashimoto’s as a root cause of low thyroid function.

Advanced Full Thyroid Panel

One of the biggest advantages the advanced full thyroid panel is a clearer picture of the root cause of your underactive thyroid. If you have been struggling with hypothyroidism for a while with no success – definately wort doing the full thyroid panel.

Full thyroid panel includes TSH, free T4, Free T3, thyroid antibodies anti TPO and anti-TG plus reverse T3. Reverse T3 is one of those less known markers but tells you a lot about not only thyroid but also overall health and stress levels. Additionally iodine – one of the most deficient minerals and at the same time essential for optimal thyroid health. Iodine and tyrosine (amino acid) are your key building blocks of thyroid hormones. If you are active woman and working out a lot – definitely worth taking a closer looks at iodine level as you can lose decent amount of iodine with sweat during the training. Click here to read more about it.

What other test is worth doing to treat your hypothyroidism effectively?

Fasted insulin! Insulin is associated mostly with diabetes by many people. You may be surprised but there is strong correlation between elevated insulin and thyroid dysfunction. Yet nobody is really checking it! Insulin is also closely related with weight gain – one of the most common symptoms of under active thyroid or Hashimoto’s. You can read here more about how insulin is linked with thyroid and other common conditions (heart diseases, PCOS, acne and even neurodegenerative diseases like Alzheimer’s). The most important thing to know about insulin is that it’s not the same as glucose or HbA1c. You can have normal glucose or HbA1c levels with elevated insulin. Insulin is your early predictor of metabolic diseases, ageing and much more!

If you are interested in a comprehensive thyroid blood test and getting to the bottom of your thyroid issues – drop me a message and we can find the appropriate testing package for you.

Why thyroid conditions are so commonly under diagnosed?

Under active thyroid is quite often misdiagnosed or diagnosed too late because of limited testing offered by GP. Similar with Hashimoto’s. Symptoms of Hashimoto’s are nonspecific and can seem unrelated at the beginning. Usually it takes years to develop Hashimoto’s. Click here to read more about mysterious symptoms you may experience that may be linked to your thyroid.

Quite often you can have inflamed thyroid with elevated thyroid antibodies for years but TSH and T4 still being within range or normal.

Why TSH and free T4 are not enough?

The standard practice among GPs to screen for thyroid health includes only TSH and Free T4. That unfortunately doesn’t give you full picture and it doesn’t even show your free T3 levels which is the active thyroid hormone.

Undoubtedly, free T3 is the most important one responsible for your metabolism and wellbeing.

With TSH and free T4 only you are not able actually see what is the root cause of your thyroid problems. Is it:

  • T4 – T3 thyroid hormone conversion issue
  • Hashimoto’s and elevated thyroid antibodies
  • Lack of “raw materials” to make you thyroid hormones
  • Elevated reverse T3 that is stealing your active hormones. Click here to read more about importance of reverse T3
  • or other issue like hormonal imbalance, cell receptor insensitivity or nutrient deficiencies with iodine being the most common. If you are not sure if you are getting enough iodine from food read my other blog post here – it can give you a bit more insight into if you are consuming enough of iodine rich foods on daily basis.

Why you feel unwell with thyroid results “within range”?

Additionally standard lab ranges for thyroid tests are very wide and will show you that something is abnormal when the disease process is already very advanced. The range for TSH is between 0.3 and 4.2. The problem is that for optimal health and thyroid function it should be between 1 and 2. 

That’s why many people are sent back home with “normal” blood results while feeling unwell with range of symptoms. The earlier  thyroid dysfunction is detected the quicker you can fix it.  Ask your doctor to run full thyroid panel or do it privately on your own and always look at the functional medicine reference ranges – they will give you optimal levels necessary to feel good:) 

What full thyroid test panel should include?

TSHIt’s not the thyroid hormone itself but a “signalling molecule” produced by pituitary gland that instruct your thyroid to make more or less of T4 depending on your levels in the blood. Low levels are usually associated with hyperthyroidism and high levels may indicate underactive thyroid. TSH is not enough to assess your thyroid health as it doesn’t show levels of your thyroid hormones, that’s why it’s important to run free T4 and free T3 test alongside to understand what’s is really going on
Free T4It measures amount of free, unbound T4 hormones in your blood. Total T4 is the sum of both free unbound T4 and T4 bound to protein however what matters more is amount of your free T4 levels. Low levels of FT4 may indicate overreactive thyroid, while high levels are linked with under active thyroid or dysfunction in your thyroid transporters.
Free T3That’s one of the most important markers as that’s your active form of thyroid hormone. Similar as Free T4, it’s the unbound form (bioavailable) of T3 hormone that is ready to be used by your cells. T4 is converted to T3 in the peripheral tissues like your gut and liver. Free T3 is also known as the “gas” that fuels all the processes performed in your body. It’s the active form of your thyroid hormone that you need the most at the end of the day. Low free T3 is linked with low thyroid function and elevated levels with over reactive thyroid.
Reverse T3Less known but useful if everything else looks “normal” and you still feeling unwell. Reverse T3 is also known as the “breaks” and it inactivates your active free T3. High levels of reverse T3 can be responsible for symptoms of hypothyroidism, since it competes with free T3 for cell receptor sites. This is an additional marker to help determine what’s going on and indicate the root cause of your thyroid problems
Thyroid Peroxidase (TPO) and Thyroglobulin (TG) antibodiesThese are two markers that will help you determine if you have autoimmune condition or not.  Thyroid peroxidase (TPO) is an enzyme that plays role in thyroid hormones production. Elevated levels can be sign of Hashimoto’s, sometimes it’s raised in Grave’s diseases as well.
Thyroglobulin (TG) is a protein/precursor of thyroid hormones. Elevated antibodies against thyroglobulin may be raised in Hashimoto’s as well.

The important thing to keep in mind is that you don’t have to have abnormal basic thyroid markers to have Hashimoto’s. Untreated Hashimoto’s will lead to thyroid damage over time and you may start seeing TSH, FT3 and FT4 outside the range – however sometimes it may take months or years.

If your antibodes are out of range, you can read more here how to lower your thyroid antibodies naturally.

What are optimal thyroid hormone levels? Functional medicine range

What is important, when you are looking at your thyroid blood tests results always look at the functional medicine reference range. As it will gives you better picture of thyroid health and helps you understand why you feel unwell.

Thyroid markerStandard Lab RangeFunctional Medicine Optimal Level
TSH0.4 – 4.2 mIU/L1 – 2.5mIU/L
Free T40.8 – 1.8 ng/dL1.1 – 1.6 ng/dL
Free T32.3 – 4.2 pg/mL3.2 – 4.2 pg/mL
Anti-TPO< 35 IU/mL< 9 IU/mL
Anti-TG< 1 IU/mL< 1 IU/mL
Reverse T3*8- 25 ng/dL8–15ng/dL
* with reverse T3 is important to look at reverse T3 to free T3 ratio as well

How to interpret you thyroid blood test results?

If you interpret thyroid tests correctly and refer to the optimal ranges according to functional medicine reference ranges, they can help you detect any thyroid dysfunctions much earlier!

  • Subclinical Hypothyroidism: TSH rises above 2-3 with normal T3 and T4 and no thyroid antibodies
  • Hypothyroidism: TSH above 3-4, with normal to low T4 and T3 and no thyroid antibodies
  • Hashimoto’s: Anti – TPO above 20 with TSH, T4 and T3 fluctuating depending on the stage of disease. Anti – TG above 6.
  • Hyperthyroidism: TSH below 0.4 with T4 and T3 normal to high and no thyroid antibodies
  • Grave’s Disease: Presence of TR or TSI antibodies. TSH below 0.4 with T4 and T3 in an upper range

What else to know?

Lastly, thyroid is quite complex and sometimes you may go from overreactive thyroid to underactive thyroid, especially in presence of autoimmunity. If you are not sure about your thyroid tests result or looking for a full thyroid panel to do in UK – just drop me an email 🙂

Frequently Asked Questions

It's not required however for best accuracy do thyroid blood test first thing in the morning. TSH tends to fluctuate during the day and afternoon blood sample collection can give false "normal" results

First thing in the morning between 8 and 9am is the best time to do the thyroid test

Coffee, because of caffeine content can interfere with thyroid blood results. Best to drink water only if you have thyroid blood test scheduled for the morning

6 weeks is minimum before you re-test your thyroid levels. If you are on your thyroid healing journey,  doing thyroid blood test every 3 months is reasonable to track progress and re-adjust your treatment plan

Yes, you can certainly do home thyroid test (finger prick blood sample collection). It's very convenient and accurate test, the only draw back is that the blood sample tends to clot during the transport so sometimes you may need to re-perform the test if that happens

To get to the root cause of hypothyroidism there are few other basic markers worth checking: vitamin D, iron & ferritin, vitamin B12, folate and insulin. That will give you much better idea what's going on in your body and what is causing low thyroid function.

Yes! Especially if you have struggled with hypothyroidism for a while with no clear improvement. Reverse T3 will help you to narrow your search for the root cause of hypothyroidism. Elevated reverse T3 will be "stealing" your active T3 hormones (free T3). High reverse T3 is usually a result of high stress, malnutrition/malabsorption or increased inflammation

The ideal TSH level is between 1 and 2 however it's not the best marker to use to asses your thyroid health. Free T3 levels are more important if you are looking to feel good again. For optimal health you need your free T3 levels to be at least 4.6pmol/L or 3pg/ml.

Insulin resistance – hidden cause of hypothyroidism and weight gain
Is low energy and weight gain persisting despite diet and exercise? It …
Causes of Hypothyroidism: From Emotional Stress to Mineral Deficiencies
Hypothyroidism is a condition that mostly affects women and manifests in various …