FREE THYROXINE-FREE T4

The Free T4 test is one of the laboratory tests which determine the amount of free thyroxine (T4) that is circulating in the blood. T4 is one of the hormones that is produced and secreted by the thyroid tissue which is gland shaped like a butterfly in the neck region. The thyroid glands have a crucial role in body metabolism as well as in the growth and development of the body. For this purpose, Free T4 test is used in evaluating thyroid function and diagnosing potential thyroid ailments.

This test applies a laboratory method known as immunoassay, which determines the quantity of free T4 found in a person’s blood. The test is as uncomplicated as it is promising, pain-free, and commonplace.

A Free T4 test measures the amount of thyroxine (T4) that’s not bound to proteins in the bloodstream. Free T4 is a form of T4 that is bioactive. The test result is given in concentration of free T4, for example, a level of free T4 is measured in pg/dL.

Generally, Free T4 tests are performed:

• To check on the functioning of the thyroid gland for hyperthyroid (highly active thyroid) or hypothyroid (less active thyroid) symptoms.
• For regular checks for individuals with a history of thyroid disorders or thyroid cancer.
• To screen and detect any possible thyroid diseases like Graves’ disease or Hashimoto’s thyroiditis.
• After thyroid hormone replacement therapy to check if treatment was effective.

Risks:

• Pain, bleeding and bruising at the needle site while blood is drawn.
• There is a chance of infection occurring at the site where the needle was inserted.

Limitations:

• The test might fail to accurately identify the presence of a thyroid disease for a person suffering from liver or kidney ailments.
• Results may also not be accurate for patients using specific drugs such corticosteroids or phenytoin.
• Patients with thyroid nodules or cancer might also find the test inappropriate.

The Free T4 test involves evaluating the following parameters:

• Free T4 Level (pg/dl)
• Optional: Thyroid Stimulating Hormone (TSH) Level
• Optional: Thyroid Hormone Levels

Some of the people who may benefit from the Free T4 test include:

• People who have symptoms of hyperthyroidism or hypothyroidism, which might show up as weight changes, fatigue, or even mood fluctuations
• People who have a history of thyroid disorders or even thyroid cancer
• People having a genetic predisposition to thyroid disorders
• People who are on medication that need them to take thyroid hormone replacement therapy

• To identify cases of abnormal clinical function of the thyroid gland like hyperthyroidism or hypothyroidism
• To follow the activity of the gland as well as revise treatment protocols
• To check the effectiveness of the medication administered in patients receiving thyroid hormone replacement therapy
• To screen a population for individuals who may suffer from these disorders in the future.

Those diagnosed with the following conditions can benefit from using the Free T4 test:

• An overactive thyroid gland is termed Hyperthyroidism
• An underactive thyroid gland is termed Hypothyroidism
• Graves' disease
• Hashimoto's thyroiditis
• Thyroid nodules or even thyroid cancer**.**

Fasting: Not required

Prerequisites: None

**Eligibility:**All ages are eligible

Test Procedure: A venipuncture blood draw will be performed.

Caution before taking the test: Notify your healthcare professional if you are on medication and have any medical issues.