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Free
T4

£29

T4 (thyroxine) is the main hormone produced by the thyroid gland. Most of it is bound to proteins and while bound cannot be converted into T3. This blood test measures levels of unbound or free T4.

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check_circle1 test included
schedule1 day turnaround   info
invert_colorsBlood - finger-prick or venous   info

Free T4

About this test

The vast majority of thyroid hormones circulating in the blood are bound to carrier proteins. Some conditions can cause the number of carrier proteins in the blood to rise or fall. Raised oestrogen due to pregnancy or birth control pills, elevated cortisol and liver failure can all affect the level of carrier proteins. The more T4 that is attached to carrier proteins the less there is available to be converted to T3, which regulates metabolism. This is why looking at levels of free T4 can be helpful in diagnosing a thyroid condition when total T4 levels are within the normal range.

Who is this test for?

This is a test for people looking to check their levels of free T4 in their blood in order to assess how well their thyroid is functioning. This test is often used following an abnormal thyroid function test to gain further insight into the diagnosis.

How it works

Collect Sample

We send you an easy-to-use kit to collect your blood sample.

Post Sample

Post your sample to our lab in the prepaid envelope provided.

View Results

View results securely in your own personal dashboard.

Important Information

Our tests are not a substitute for seeing your doctor, especially if you are suffering symptoms. Our doctors will interpret your results based on the information you have provided, but will not diagnose, consult or provide any treatment. You will be advised to see your doctor for any necessary follow-up action.

Tests Included

Thyroid Function

Thyroxine (T4) is one of two hormones produced by the thyroid gland. Most T4 is bound to carrier proteins in the blood. This test measures the level of T4 which is free, or unbound, circulating in your blood.

High levels of free thyroxine can indicate an overactive thyroid while low levels can indicate an underactive thyroid.

Finger-prick blood sample collection kit

We will send you your Free T4 finger-prick blood test sample collection kit which contains everything you need to take your blood sample in the comfort of your own home. If you are unsure about completing a finger-prick blood sample collection you will have the opportunity to select a clinic-based venous blood sample option during the checkout process.

How to collect a finger-prick blood sample

Postage & packaging

Your Free T4 test includes 1st class postage and packaging for you to send your blood sample directly to our laboratory for analysis. If you live in an area where you cannot rely on the post or you simply want to ensure that your sample arrives at the laboratory the following day, you may wish to send your blood sample guaranteed next day delivery for extra reassurance.

Private laboratory analysis

Your blood sample will be analysed at one of our chosen laboratories. You can be assured of fast, accurate results from one of our accredited independent providers of clinical diagnostic tests.

Interpretation of results

Our medical team will comment on out-of-range blood test results and give you follow-up advice where necessary. If you need it, a PDF copy of your Free T4 test results can be downloaded for your doctor.

Secure online account with mymedichecks.com

Once you have placed your order you will receive login details to mymedichecks.com where you can manage your account, track your orders and view your Free T4 test results.

Health and Lifestyle tracker

Stay motivated by filling in your online health and lifestyle questionnaire and seeing how improvements in your lifestyle can influence your test results. Your medical and family history gives us vital information when interpreting your results.


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