A blood test to establish the level of T3 (triiodothyronine) - the active thyroid hormone which regulates metabolism in our cells.

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check_circle 1 test included
schedule 2 day turnaround info
invert_colors Blood - finger-prick or venous info
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About this test

T3 (triiodothyronine) is converted from T4 in our tissues (mainly the liver) by the removal of an atom of iodine. T3 is the active thyroid hormone which regulates metabolism by controlling the rate at which oxygen and calories are converted to energy in our cells. If T4 is low then it is likely that T3 will also be low. In an overactive thyroid T3 is often raised before T4 and returns to normal after T4.

It is not always the case that a low T3 reading signifies a problem with the thyroid gland. Sometimes T3 can be low even when T4 is normal as a result of conversion problems: in times of stress the body will convert T4 to reverse T3 (rT3) an inactive form of T3 in order to conserve energy; at other times mineral deficiencies can cause conversion problems, especially if selenium and zinc are low.

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

Finger-prick blood sample collection kit

We will send you your T3 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 T3 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 T3 test results can be downloaded for your doctor.

Secure online account

Once you have placed your order you can visit my.medichecks.com where you can manage your account, track your orders and view your T3 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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