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Thyroid function lab test kit

The Thyroid Function Test is a blood sampling kit you can use at home, to check whether you might have an underactive thyroid. 

The kit comes with a prepaid envelope, so you can easily send your sample to our partner lab to be analysed. Click below to get started and buy your Thyroid Function Test Kit online. Most orders are delivered from our pharmacy within one working day.

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PLEASE NOTE: This treatment is not available through our online pharmacy service. This page is for information only. If you are experiencing any of the symptoms related to the condition(s) this medication treats, we strongly recommend that you see your GP in person.

This content was reviewed by a clinician on

28 November 2019
dr daniel

Dr Daniel Atkinson

(GP Clinical Lead - GMC No. 4624794) 28 November 2019
Product information

The Thyroid Function Test Kit can help to show whether you have an underactive thyroid (hypothyroidism) or are at risk of developing an underactive thyroid. It can be useful for people who want to monitor their thyroid function because they are taking treatment for hypothyroidism, or have been advised to do so by a doctor because they are more susceptible to thyroid problems. The test kit uses a blood sample which can be collected at home, and is sent off to a lab for analysis.

We have two tests available. The first test measures levels of thyroxine in the blood, also known as T4. Low levels of this hormone indicate an underactive thyroid. It also checks for a hormone called TSH, or thyroid-stimulating hormone. Higher than usual levels of TSH but normal levels of T4 can be a sign that you are more likely to get an underactive thyroid. 

The other test we offers measures triiodothyronine, or T3 levels, as well as T4 and TSH.

What is the thyroid gland?

The thyroid is a gland located situated in the neck. The hormones it produces, thyroxine (T4) and triiodothyronine (T3) help the body to convert fats from food into energy. When the production of these hormones is lower than normal, it’s called hypothyroidism. 

What does hypothyroidism look like?

Symptoms of hypothyroidism include feeling tired, gaining weight more easily, becoming constipated, depression, cramps and aches in the muscles, loss of sex drive, irregular periods, and feelings of numbness in the hands and fingers. You should consult a doctor if you develop any of the above symptoms. Getting them doesn’t mean that you have an underactive thyroid, but seeking advice is important; if you have hypothyroidism and it isn’t treated, it can lead to complications.

How is an underactive thyroid diagnosed?

The only way to diagnose an underactive thyroid is through a thyroid function test. 

The most commonly issued treatment for an underactive thyroid is levothyroxine, which is a type of hormone replacement therapy, and works by supplementing thyroxine (T4) levels in the body. Some people may be advised to take a different type of medicine, called liothyronine. This is also a form of replacement therapy, but supplements levels of triiodothyronine (T3) instead of T4.

What about overactive thyroid?

This a problem where the thyroid gland produces too much T4 or T3. It can cause sleeping problems, weight loss, twitching or tremors, and heat sensitivity. Again, it’s important to see a doctor if you have any of these symptoms, or think you might have an overactive thyroid, as it can lead to serious problems if it isn’t addressed. 

How to test your thyroid function at home

The Thyroid function test enables you to check your thyroid levels after providing a sample at home. It comes with a prepaid envelope, so you can send your sample off to be tested. We work with a trusted UK laboratory, who will analyse your sample and turn around most blood tests within a few hours of receipt. Results are posted to your secure patient area, and our doctor will provide guidance on what to do next based on your result where required. 

Page last reviewed:  28/11/2019

It is very important to follow the instructions provided with the kit when collecting your sample. This will help to ensure that your test result is as accurate as possible. 

  1. First, fill in the name label and request form using a blue or black ballpoint pen.
  2. Do not stick this label to the tube until after you have collected your sample.
  3. Place the blood collection tube in the protective packing wallet as shown in the leaflet, and remove the lid.
  4. The recommended site to collect a sample from is the side of your little fingertip.
  5. Wash your hands using soap and warm water. This will ensure your hands are clean but also help the blood flow to your hands and fingers.
  6. It can also help to soak your hand in warm water beforehand to help get blood flowing. 
  7. Dry your hands with a clean towel.
  8. Wipe the tip of the finger you are going to take a sample from with an alcotip swab, then wipe it with a dry clean tissue. A blood drop will only form if your finger is dry.
  9. Take one lancet out of the bag, and twist the cap to remove it. This should expose the needle.
  10. Place the lancet needle against the side of your little finger. To activate it, press it against your finger firmly. You should feel a small pinch, then remove the lancet.
  11. You should find that blood flows more easily to the site if you stand and let your arm hang down. 
  12. When the first droplet forms, wipe this away with a clean tissue.
  13. Massage the side of your hand down to your little finger.
  14. Holding your finger over the blood collection tube, allow blood to drop into it while massaging.
  15. Continue until the tube is full to the upper line.
  16. If you cannot get enough blood to come out, follow the same process with your little finger on the other hand.
  17. If the droplets stop, it might also help to wipe the puncture with a clean tissue and wait for 10 seconds, then trying again.
  18. When the tube has been filled up to the required line or just over, you can stop collecting blood and fix the lid onto the tube. Push this down firmly until you hear a click. This indicates that the tube is securely closed.
  19. Then invert the tube between five and 10 times.
  20. Adhere the name label to the tube as shown in the diagram on the leaflet, with the middle applied first and the sides meeting on the other side.  
  21. Then put the tube inside the protective wallet.
  22. Place this wallet inside the test kit box, along with the used lancet(s). 
  23. Seal the test kit box with the security sticker.
  24. Place this inside the pre-paid envelope along with the request form.
  25. Check you have included everything you need to, then seal the envelope and post to The Doctors Laboratory at your earliest convenience.

If you are unsure of anything to do with this test, please contact The Doctors Laboratory on 020 7307 7373 or by email on samples@tdlpathology.com.

Alternatively, you can also contact our customer care team on 0207 043 0716 or by email on customercare@treated.com

Page last reviewed:  28/11/2019
Please read the patient information leaflet for this medicine fully before use:

Thyroid function lab test kit


This kit contains:

  • a test kit box
  • a request form
  • a name label
  • a security label
  • two moist wipes
  • two alcotip swabs
  • two small round plasters
  • a blood collection tube
  • a protective packing wallet
  • and three blue lancets.

If you receive your kit and one or more of the above items are missing, please contact our customer care team.

Page last reviewed:  28/11/2019
Please read the patient information leaflet for this medicine fully before use:

Thyroid function lab test kit


How does it work?

The test uses a sample of blood to check thyroid levels. T3, T4 and TSH are all present in the blood. If someone has low T3 or T4 levels in the blood, it can be an indication of an underactive thyroid gland. If someone has high levels, it can mean they have an overactive thyroid gland.

Normal T3 or T4 levels, but high levels of TSH, can indicate that someone may develop an underactive thyroid in the future, and need to be tested regularly.

Who is your partner lab?

We work with trusted UK lab TDL Pathology

How will I be notified?

Once your result is ready, you’ll be notified via SMS or email that it is ready to view in your patient area. If our doctor needs to speak to you about your result, they’ll contact you to arrange a good time to call.

How long does it take?

We ship all test kits by next day courier. The lab turns most samples around within a few hours of receipt. Provided you do not delay collecting your sample and returning it, you should be able to get your result within five to seven days of placing your order for your test kit.

What kind of sample do I have to give for the test?

A blood sample from the side of the little finger tip. A lancet is provided to help you collect this.

Will it hurt?

You should only feel a small pinch when you use the lancet.

What happens if my levels are sufficient?

You’ll be notified in your patient area. If you’re taking treatment for an underactive thyroid, your course of treatment will likely stay the same. 

If your T3 or T4 levels are normal, but your TSH levels are high, you may be advised to take a repeat test in a few weeks or months.

What happens if my levels are low?

Our doctor will provide advice advice on what you should do next. If you are already taking treatment for an underactive thyroid, this may mean speaking to a doctor and slightly adjusting your treatment plan. If you’re not taking treatment, then you may need to have a prescription for hormone replacement therapy started.

Getting the Thyroid Function Test kit online

We post all test kits by next-day delivery. To buy the Thyroid Function Test from our UK pharmacy, click below to go to our short order form. 

Page last reviewed:  28/11/2019
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