Triiodothyronine Free

Also known as T3 - Free

You need to provide

Blood

This test is for

Male, Female

Test Preparation

No special preparation is required.

Understanding Triiodothyronine Free

What is Triiodothyronine Free?

A Triiodothyronine Free test measures the level of free triiodothyronine (FT3) hormone in the blood. This test helps assess overall thyroid function and detect possible thyroid disorders. It is also performed in combination with free T4 and TSH tests as part of a thyroid profile free test.

The thyroid is a small, butterfly-shaped gland located at the front of your neck. It produces a hormone called triiodothyronine, also known as T3, that helps regulate the body’s metabolism & growth, heart rate, and temperature; RBC production; the development of the tissues; and the functioning of the brain. This T3 hormone, an active form of thyroid hormone, exists in the blood in two forms: free T3 (the form that is not bound to proteins) and bound T3 (the form attached to proteins).

A Triiodothyronine Free test measures the free form of the T3 hormone as abnormal levels of FT3 can help detect hyperthyroidism (the thyroid gland produces too much thyroid hormone) or hypothyroidism (the gland produces less thyroid hormone). Your doctor may suggest this test if you show symptoms of hyperthyroidism, like increased appetite, weight loss, sweating, anxiety, tremors, etc., or hypothyroidism, like fatigue, weight gain, dry skin, constipation, etc. Additionally, a T3-free test is also used to determine the effectiveness of thyroid medications and abnormalities of the proteins that bind thyroid hormones.

No special preparations are needed for this test. However, let your doctor know about all the medications you take as some of them can affect thyroid function. Biotin (Vitamin B7) is a commonly taken over-the-counter supplement that can lead to some aberrancy in your thyroid test results even if they are normal. Therefore, avoid taking biotin 2-days before this test.

Test result ranges are approximate and may differ slightly between labs depending on the methodology and laboratory guidelines. Talk to your doctor about your specific test results. The results will help them evaluate your medical condition, make recommendations for lifestyle modifications such as diet and exercise, assess whether or not medication will be required to manage your condition, and formulate your overall treatment plan.

What is Triiodothyronine Free used for?

A Triiodothyronine Free test is done:

To measure the levels of free T3 hormone in the body.
As part of a free thyroid profile along with free T4 and TSH tests.
To evaluate symptoms suggestive of an imbalance in thyroid hormone levels, such as fatigue, weight loss, hair loss, and changes to heart rate.
To diagnose and monitor the treatment of hypothyroidism or hyperthyroidism.
To detect an underactive thyroid gland in newborn babies.
To evaluate other disorders, such as thyroid nodules, goiters, and pituitary or hypothalamus gland disorders.

What does Triiodothyronine Free measure?

A Triiodothyronine Free test measures the levels of free triiodothyronine (T3), a hormone that is produced by the thyroid gland. T3 hormone plays an important role in regulating the body's metabolism, energy levels, and growth & development. It exists in the blood in two forms: free T3 and bound T3. Only a small portion of T3 is in the free form (not bound to proteins) and can be utilized by the body’s tissues, whereas more than 99% T3 is bound to proteins, such as albumin and thyroid-binding globulin (TBG), which prevent it from entering into the tissues. The body maintains a balance between bound and free T3 to ensure proper functioning.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Triiodothyronine Free

Frequently Asked Questions about Triiodothyronine Free

Q. Why is a Triiodothyronine Free test done?

A Triiodothyronine Free test is done to measure the levels of the free form of T3 hormone in the body and evaluate the proper functioning of the thyroid gland.

Q. Is fasting required for an FT3 test?

Usually, fasting is not required before taking this test. However, it’s recommended to follow any specific instructions provided by your doctor.

Q. Can I take a Triiodothyronine Free test during pregnancy?

Yes, you can take this test during pregnancy. This test is usually recommended during pregnancy along with some other tests to measure the levels of thyroid hormones, as thyroid disorders can complicate pregnancy.

Q. How can hyperthyroidism affect a pregnant woman and her baby?

An untreated hyperthyroidism during pregnancy can lead to miscarriage, premature birth, low birth weight of the baby, preeclampsia (a very high rise in blood pressure in late pregnancy), thyroid storm (a sudden, severe worsening of symptoms of hyperthyroidism), and congestive heart failure.

Q. Is there any risk associated with an FT3 test?

There is usually no risk associated with this test. However, some people may feel a slight sting when a needle is pricked to collect a sample and may experience some bleeding that is normal and usually not bothersome. Rarely, some people may experience slight swelling or bruising at the site of the needle prick. Applying ice 3-4 times a day for about a week may help reduce swelling and bruising. If it does not get better, consult your doctor.

+ more