Thyroid Hormone Levels
Order home thyroid test kits online and get free, contactless home delivery that's discrete and reliable.
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Order your test kit, take your sample, and send to our UK-accredited partner laboratory. Results and advice from our doctors will be ready in 2 to 3 days.
The thyroid is a gland located in the neck. It’s responsible for producing two hormones:
- Thyroxine (T4)
- Triiodothyronine (T3)
The cells in your body require these hormones to function normally because they regulate the speed at which cells work.
Testing your thyroid hormone levels can identify whether they may be too high or too low, which would indicate an overactive thyroid or an underactive thyroid.
About thyroid hormone levels
Who can get tested online?
Anyone can order home thyroid testing online. As long as you’re over 18 you can get tested through our service. It doesn’t matter if you already have a diagnosed thyroid condition or not, or if you’re already receiving thyroid treatment or not.
How to place your order
Using a home test works in the following steps:
- Place an order and get your kit delivered to your door, or collect from a local post office (delivery is free)
- Collect a few drops of blood using a finger-prick test
- Send your samples to our UK-based, accredited partner laboratory (postage is free)
- Once your results are available (in 2 to 3 days), our doctors will review your results
- One of our doctors will contact you, via a secure and confidential message in your patient account, to let you know your results and give you advice and support on what to do next
In some cases, the doctor may need to ask for more information. They may contact you by phone, so make sure your telephone number is up to date in your online account.
How the test works
The thyroid test is simple and easy to use:
- The test will contain 3 lancets (a device for pricking your finger) and a collection tube
- Collect a drop of blood from your finger using a lancet
- Place the drop of blood into the collection tube
- Use the pre-paid envelope to post to our partner lab
- Your sample will be used to test your cholesterol levels
- Get the results 2 or 3 days after your sample arrives at the lab
- A ZAVA Doctor will then send you advice based on your results
The thyroid is an ‘endocrine’ gland located in the neck which produces two hormones. These hormones, thyroxine and triiodothyronine, regulate how fast cells work, which is also known as your ‘rate of metabolism’. So, your thyroid hormone levels are important for controlling the activity of your cells.
If your thyroid hormone levels are too high, it can be a sign of hyperthyroidism (overactive thyroid). And if they’re too low, it can be a sign of hypothyroidism (an underactive thyroid).
Thyroid disorders are very common and usually affect more adult women than men. But, anyone can be affected, including men, babies, and children. It’s estimated around 1 in 20 people worldwide have a thyroid disorder.
Your thyroid can be found at the front of your neck just underneath your Adam’s apple. The thyroid is made up of two lobes lying on either side of your windpipe.
The standard ranges for thyroid hormone levels are:
- Thyroid stimulating hormone (TSH): 0.4 - 4 milliunits per litre (mU/L)
- Free thyroxine (T4): 9.0 - 25.0 picomoles per litre (pmol/L)
- Free triiodothyronine (T3): 3.5 - 7.8 picomoles per litre (pmol/L)
But, each lab that tests for thyroid hormone levels may use slightly different units to record thyroid hormone levels. In this example it’s picomoles per litre but it can also be others, like milliunits per litre.
The body has a natural feedback system which works to make sure our thyroid hormone levels are within the normal ranges. However, if this system isn’t working properly, it can cause hyper- or hypothyroidism.
For example, if thyroid hormone levels fall, more thyroid stimulating hormone (TSH) will be released by the pituitary gland in the brain. TSH controls the amount of T4 and T3 produced by the thyroid gland. Equally, if too much of these hormones are produced, the release of TSH will stop.
If your thyroid hormone levels are low it may be a sign of an underactive thyroid. Symptoms include:
- Tiredness (fatigue)
- Weight gain
- Feeling cold
- Muscle aches, cramps, and weakness
- Dry, scaly skin
- Brittle hair
- Loss of sex drive (libido)
- Slow movements
- Pain, numbness or tingling in hands and fingers
- Irregular or heavy periods
If your thyroid hormone levels are low, your thyroid isn’t producing enough of these hormones and so your metabolism may be slow. In other words, your cells are working more slowly which is why you may experience these symptoms.
Hypothyroidism can be caused by an underlying autoimmune disease, where your own immune system attacks your body, called Hashimoto’s Thyroiditis. This disease causes your own immune system to attack your thyroid gland, which then stops the release of thyroid hormones that your body needs for metabolic processes.
The signs and symptoms of an underactive thyroid or Hashimoto’s Thyroiditis may not develop until later into the condition. So, it’s possible to have hypothyroidism and not be showing any symptoms.
If left untreated, hypothyroidism can:
- increase your risk of cardiovascular disease
- cause an abnormal swelling of the thyroid gland, which is called a goitre
- in rare cases, cause a coma
It can also lead to pregnancy complications, like:
- Anaemia in the mother
- Birth defects
- Bleeding after birth
- Stillbirth or miscarriage
- Premature baby
If your thyroid hormone levels are high, this can be a sign of an overactive thyroid. Symptoms include:
- Mood swings
- Difficulty sleeping
- Increased heart rate
- Weight loss
- Swelling in the neck called a goitre
- Heat sensitive
These symptoms occur because your thyroid gland is producing too much of the thyroid hormones, so your cells are working at a faster rate than normal.
An overactive thyroid can be caused by:
- Graves’ Disease – an autoimmune condition where the immune system attacks the thyroid
- Thyroid Nodules – benign lumps on the thyroid gland causing an overproduction of thyroid hormones
- Medication – iodine-containing medication can cause the thyroid to overproduce thyroid hormones
There are a few complications associated with an overactive thyroid.
- Watery eyes
- Feeling dry and gritty
- Red eyes
- Bulging eyes
- Sensitivity to light
- Premature birth
- Low birthweight
An underactive thyroid is also a possible complication related to having an overactive thyroid because it can often happen as a result of getting overactive thyroid treatment.
Thyroid storm – this can occur if the overactive thyroid is undiagnosed or poorly controlled. It can be triggered by:
- Not taking medication as directed
You can request a blood test from your GP. In this case, it’ll usually be a full blood test, where a sample will be taken from a vein in your arm.
At ZAVA, we also offer a blood test kit for checking your thyroid hormone levels (TSH and T4) at home. This is how it works:
- We’ll send you a test kit for you to use at home, which you’ll get within 1 to 2 days of placing your order
- You’ll need to provide a small blood sample and use the pre-paid envelope we provide in the kit to post it to our partner lab
- Your results will be ready 2 to 3 days after your sample reaches the lab. At that point, we’ll let you know when they can be viewed in your account
The typical treatment for an underactive thyroid is a daily hormone replacement in the form of a tablet called ‘levothyroxine’.
Levothyroxine replaces the hormone your thyroid isn’t making enough of. Usually, you’ll need regular blood tests to figure out the right dose, which means it can take a while to get right.
Levothyroxine is taken once per day. You should take your pill at the same time every day, ideally in the morning. You should swallow them with water and wait half an hour before eating. This is because the effectiveness of levothyroxine can be affected by food, supplements, or other types of medication.
Combination therapy isn’t a popular choice of treatment in the UK because there’s a lack of evidence to support that it’s better than levothyroxine alone.
Combination therapy uses levothyroxine and triiodothyronine (T3) together. It may be recommended if someone has a history of thyroid cancer.
There are three main treatments for an overactive thyroid:
- Radioiodine treatment
The medication used to treat an overactive thyroid are called ‘thionamides’, which stop the thyroid from producing excess hormones.
The main types are:
These types of medication can have side effects, including:
- Upset stomach
- Aching joints
- Itchy rash
When your hormone level is under control, your dose may be reduced and even eventually stopped. However, some people need to take the medication for the rest of their lives.
Using radiation can be very effective at stopping your thyroid from producing high levels of hormones.
- highly effective
- given in drink or capsule form
- absorbed by your thyroid to stop it over-producing thyroid hormones
- usually only required once
With radioiodine, it can usually take up to a few months for you to feel the full benefits of the treatment.
Surgery to remove your thyroid may be right for you if:
- you have a goitre (your thyroid gland is swollen)
- your overactive thyroid is causing eye problems
- medication or radioiodine isn’t right for you
- your symptoms return after trying medication or radioiodine
If you’re experiencing any symptoms like those associated with a hypo- or hyperactive thyroid, you should consider a thyroid test.
If you have a thyroid test and your results are abnormal you should speak to your GP as soon as possible to discuss starting treatment.
Dr Babak Ashrafi Clinical Lead for Service Expansion
Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.Meet our doctors
Last reviewed: 02 Aug 2022
Anderson, P. (2015). Hashimoto’s disease: the underactive thyroid disease. Master of Science in Nursing (MSN) Student Scholarship: 121.
British Thyroid Foundation. (2018). Your thyroid gland. BTF. [online] Available at: https://www.btf-thyroid.org/what-is-thyroid-disorder [accessed 19 December 2018].
Holm, I. A. et al (2005). Smoking and other lifestyle factors and the risk of graves’ hyperthyroidism. Arch Intern Med; 165: 1606-1611. [online] Available at: https://pubmed.ncbi.nlm.nih.gov/16043678/ [accessed 13th May 2021]
National Health Service. (2016). Symptoms overactive thyroid (hyperthyroidism). NHS. [online] Available at: https://www.nhs.uk/conditions/overactive-thyroid-hyperthyroidism/symptoms/ [accessed 19 December 2018].
National Health Service. (2018). Treatment: underactive thyroid (hypothyroidism). NHS. [online] Available at: https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/treatment/ [accessed 19 December 2018].