Thyroid T4 Blood Test

The hormone thyroxine (T4) is a hormone produced by the thyroid. It works to speed up your metabolism. The Thyroid T4 Blood Test measures the amount of T4 in your blood, which can indicate whether your thyroid is functioning normally or not.


Why test for T4?

Common reasons for this blood test are:

  • To investigate symptoms that could indicate a problem with your thyroid
  • To get a clear picture of your thyroid function and health
  • To assess whether thyroid medication is working.

Your blood test

Our phlebotomy-trained professionals will take a blood sample from you. This sample will be analysed in the UK by our authorised partners, TDL. By booking this blood test, you agree for us to share your personal information with TDL in order to process your test. We’ll make sure you consent to this at your appointment too.

Frequently Asked Questions

No, we will send you the results and recommend that you share these with your GP or fertility provider.

It is not unusual for some bleeding to occur under the skin following your blood test and sometimes this can extend a little further around the puncture site.  If this causes you concern, check with your practice nurse. 

Sometimes we cannot get a blood sample from you. This can be for many reasons, such as not being hydrated enough, feeling cold or having another blood test recently. We will always offer you another appointment so we can try again.

Visit our FAQs page for any further questions you may have.