This hormone is made by the thyroid gland, which is responsible for many body functions.
The blood test will diagnose certain thyroid conditions like hyperthyroidism.
This article will discuss normal and abnormal free T3 levels.
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It will also cover what to expect when receiving a free T3 test.
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What Is a T3 Blood Test?
A T3 blood test measures the level of triiodothyronine hormone in the blood.
Thethyroid glandmakes triiodothyronine and another hormone called thyroxine (T4).
It is important to note that T3 blood tests are notoriously variable, even sometimes unreliable.
There are three types of T3 blood tests.
Free T3 measures triiodothyronine that is not attached to anything and freely moves in the blood.
Bound T3 measures triiodothyronine that is attached to protein.
The last test is a total T3 test, which measures free and bound T3.
A healthcare provider may order other thyroid tests, including T4 andTSHto evaluate thyroid function.
What Does a T3 (Triiodothyronine) Do?
The thyroid is a butterfly-shaped gland in the front of the neck above the collarbone.
It makes thyroid hormones, which are used for various body functions.
The thyroid primarily produces the hormone thyroxine (T4).
The T4 comes from the four iodine atoms it contains.
T4 is changed to triiodothyronine (T3) by removing one of the iodine atoms.
This is done in the liver and other tissues.
T3 is the functional form of the thyroid hormone.
However, T4 is more stable than T3.
Therefore, the body will only convert T4 to T3 as needed.
T3 and T4 work to manage how the body uses and stores energy for metabolism.
However, it is T4 levels that are more commonly tested to evaluate for a hyperthyroid or hypothyroid condition.
T3 blood tests can also be done to monitor how well thyroid treatment is working.
A healthcare provider will provide that information; no medicine should be stopped unless instructed.
A healthcare provider will take a blood sample.
A bandage will be placed over the insertion site.
You may experience a small amount of bruising and pain.
The blood sample will be processed in a lab.
Test results are reported back in a few business days.However, each location’s timing will vary.
Be sure to ask the healthcare provider performing the procedure when you should expect yourresults.
What Are Normal T3 Levels?
Normal freeT3 levelswill vary based on a person’s age.
Values can also be given in nanograms (ng) and deciliters (dL).
Anytime there is a blood result question, talk to a healthcare provider to help interpret the results.
What Do Abnormal T3 Test Results Mean?
An abnormal T3 test could indicate there is something wrong with the thyroid gland.
Results will be compared with other thyroid tests like T4 and TSH.
T3 is also high during pregnancy, especially at the end of the first trimester.
There are a few mild side effects that some people may experience.
The blood test is done similarly to other blood tests, with a blood sample taken from a vein.
MedlinePlus.Triiodothyronine (T3) tests.
American Thyroid Association.Thyroid function tests.
American Thyroid Association.Thyroid hormone treatment.
University of Rochester Medical Center.Free and bound triiodothyronine (blood).
Labcorp.Triiodothyronine (T3), free.
