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Thyroid Monitoring rT3

Everything in Thyroid Monitoring (TSH, FT4, FT3) plus reverse T3 (rT3).

This is a comprehensive test for thyroid hormones including reverse T3 (rT3). Sometimes a basic thyroid blood test which tests for TSH (thyroid stimulating hormone) and free T4 (thyroxine) can miss problems that could lead to symptoms of hypothyroidism. These include problems converting T4 to T3 (the biologically active thyroid hormone) as well as the production of rT3 instead of T3. This can happen when the body is under stress through illness, calorie restriction or even excessive exercise. Reverse T3 blocks the action of T3 in our cells and some experts believe that rT3 can cause symptoms of hypothyroidism even if levels of other thyroid hormones (T4 and T3) are normal.

This test measures TSH, FT4, as well as both free T3 (FT3) and rT3 for a thorough investigation of thyroid hormones.

Who is this blood test for

This test is for individuals who may be taking thyroid hormone replacement therapy and wish to check whether their thyroid function is optimal. They may still be suffering symptoms despite showing normal levels of TSH and T4 and want to test for FT3 and rT3 as well.

What's included

Thyroid Stimulating Hormone is produced in the pituitary gland and stimulates the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3).

High levels of TSH indicate an underactive thyroid while low levels indicate an overactive thyroid. In primary pituitary failure, a low TSH will be associated with an underactive thyroid.

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.

Triiodothyronine (T3) is one of two thyroid hormones produced by the thyroid gland. Most T3 is bound to protein in the blood. Free T3 measures the level of T3 that is free, or unbound to protein, and is available to regulate metabolism.

Normally T4 is converted to T3, the biologically active thyroid hormone. However, when the body is under stress (due to illness, starvation, extreme cold), it converts T4 to reverse T3 (rT3) which inhibits the action of T3 in our cells. This is thought to be a protective mechanism to conserve energy.

Low levels of rT3 are normal. A raised rT3 result may indicate that your cells are not receiving enough active T3, causing symptoms of hypothyroidism (underactive thyroid).

The rT3 ratio measures the level of reverse T3 in relation to free T3 in your blood. A low ratio indicates that the balance is favouring rT3, potentially leaving you with insufficient levels of active thyroid hormones in your cells. Some experts believe that a low ratio will lead to symptoms of hypothyroidism even when thyroid hormones are at normal levels. 

We will send you your Thyroid Monitoring rT3 blood and test sample collection kit together with the details of a convenient clinic where you can go and have your sample taken.

Your Thyroid Monitoring rT3 test includes 1st class postage and packaging for you to send your blood and 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 and sample guaranteed next day delivery for extra reassurance.

Your blood and 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.
Once you have placed your order you will receive login details to where you can manage your account, track your orders and view your Thyroid Monitoring rT3 test results in your own personal dashboard.
Our medical team will comment on out-of-range blood and test results and give you follow-up advice where necessary. If you need it, a PDF copy of your Thyroid Monitoring rT3 test results can be downloaded for your doctor. Want a hard-copy report? You will be given the opportunity to order one during the checkout process.

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This blood test is for reverse T3 (rT3) an inactive form of triiodothyronine which can inhibit the action of the active form (T3) in the body's cells.

Thyroid Monitoring rT3 is included in the following categories: Thyroid Health