Thyroxine binding globulin

This is an important test that is typically used to diagnose thyroid problems.

Venous blood
1 tests included
12 days turnaround



About Thyroxine binding globulin

What is thyroxine-binding globulin?

Triiodothyronine (T3) and thyroxine (T4) are the two main hormones produced by the thyroid gland. T3 is the more powerful of the two hormones, which regulate metabolism throughout the body.

The vast majority of T3 and T4 in the body is bound to other proteins, primarily thyroid-binding globulin (TBG). The remaining unbound T3 and T4 are called free T3 and T4.

A deficiency in TBG is typically associated with an underlying thyroid illness, meaning it can be used as a marker for thyroid problems. TBG deficiency does not generally cause symptoms itself.

Why take the test?

This test measures the level of thyroxine-binding globulin in the blood. It is typically used to diagnose thyroid problems.


What's tested

Thyroid Function

How it works



Purchase your Kit

Just order a test online and get your kit delivered right to your door unless you are ordering a COVID-19 Fit to Fly test where you will be given appointment options to attend our clinics across the United Kingdom for a nose and throat swab PCR test at the checkout stage.



Take your test and post

Follow our simple instructions to take your sample and post back the enclosed prepaid envelope to our accredited lab for processing. We also offer home or workplace visits by a qualified nurse. For COVID-19 Fit to Fly tests you must attend one of our partner clinics for our trained collection officers to take your sample. You will then have the results emailed to you.



Get results directly to your dashboard

You will receive an email notification from our medical team when your results are available on your secure personalised health dashboard.