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Thyroid Check Plus rT3

This profile includes everything in our popular Thyroid Check Plus (TSH, T4, FT4, FT3 and thyroid antibodies) as well as reverse T3.

This test is our most comprehensive test for thyroid function. As well as thyroid antibodies to investigate for autoimmune disease (the major cause of thyroid disorders) it includes thyroid stimulating hormone (TSH), thyroxine (T4), free thyroxine (FT4) and free triiodothyronine (FT3). T3 is the most potent thyroid hormone and is the one which is active in governing metabolism in our cells.

T4 converts to T3 by the removal of an atom of iodine. In times of stress, for example during illness or starvation, a different atom of iodine is removed instead, creating reverse T3 (rT3). This is thought to be the body's attempt to preserve energy for growth and repair. When rT3 is taken up by the body's cells it can block the action of T3 therefore slowing your metabolism. As a result your thyroid hormone levels can be normal, but because T3 can't get into your cells, you suffer from hypothyroid symptoms. 

Who is this blood test for

This test is for individuals who want a thorough examination of their thyroid function. They may already have had some basic thyroid function tests performed and now wish to get a more detailed picture. 


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.

T4 (Thyroxine) is the main hormone produced by the thyroid gland. T4 is not biologically active, and must be converted to T3 before it can become active in regulating metabolism. Some T4 is bound to proteins, while some T4 is 'free' or unbound. This test measures the level of total T4 in your blood. 

Raised T4 can indicate an overactive thyroid while low T4 may indicate that the thyroid is struggling to produce sufficient thyroid hormones. 

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. 

This test looks for antibodies to thyroglobulin, a protein which is specific to the thyroid gland. Under normal circumstances it does not enter the bloodstream, but if your thyroid is inflamed or under attack from the body's own immune system, then thyroglobulin can be secreted and antibodies detected. 

Raised levels of thyroglobulin antibodies (TGAb) can indicate autoimmune thyroid disease. 

Thyroid peroxidase is an enzyme which is produced in the thyroid gland and is important for converting T4 to the biologically active T3. This test looks for antibodies to thyroid peroxidase (TPOAb) in the blood which indicates that the body's immune system is attacking the thyroid gland and impairing its function. 

Raised levels of thyroid peroxidase antibodies are often found in Hashimoto's disease (underactive thyroid) and can sometimes be detected before any symptoms are reported. 

Raised levels are also found in over half the cases of Graves' disease (overactive thyroid). 

 

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

Your Thyroid Check Plus rT3 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 mymedichecks.com where you can manage your account, track your orders and view your Thyroid Check Plus rT3 results in your own personal dashboard.
Our medical team will comment on out-of-range blood and results and give you follow-up advice where necessary. If you need it, a PDF copy of your Thyroid Check Plus rT3 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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Thyroid Check Plus rT3 is included in the following categories: Thyroid Health