Thyroid monitoring rt3

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

Venous blood
5 tests included
14 days turnaround



About Thyroid monitoring rt3

What is a thyroid monitoring test?

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. T4 acts both as a hormone by itself and as a precursor for T3 production. 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. To stimulate the production of T3 and T4, the pituitary gland secretes thyroid-stimulating hormone (TSH). Reverse T3 (rT3) is a metabolite of T4 that is biologically inactive but functions as a competitive T3 inhibitor.

It is normal for there to be some rT3 in the blood but elevated levels of rT3 have been shown in intensive care patients and in some severe disorders. Typical thyroid testing will include T3, T4 and thyroid-stimulating hormone. Though little research has been performed on rT3, its inclusion in this test can offer a broader picture of thyroid health.

Why take the test?

This test measures the level of T3 (free and bound), T4 and thyroid-stimulating hormone in the blood. It also includes an additional test for reverse T3. The test is typically used to diagnose and monitor 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.