Home›Thyroid Profile Free (FT3, FT4 & TSH)

Content created by

Written by

BDS, MDS - Oral Pathology and Microbiology

Reviewed by

Dr. Ashish Ranjan

MBBS, MD (Pharmacology)

Want to know more?
Read our Editorial Policy

Thyroid Profile Free (FT3, FT4 & TSH)

Also known as Thyroid Function Test-Free

Thyroid Profile Free (FT3, FT4 & TSH) Includes 3 testsView All

You need to provide

Blood

This test is for

Male, Female

Test Preparation

Do not take multivitamins or dietary supplements containing biotin (vitamin B7) for at least 2 days before the test.

Understanding Thyroid Profile Free (FT3, FT4 & TSH)

What is Thyroid Profile Free (FT3, FT4 & TSH)?

A Thyroid Profile Free (FT3, FT4 & TSH) test offers a series of blood tests that measure the levels of free form of thyroid hormones in the blood. This test is used to identify the functioning of the thyroid gland and measure the levels of thyroid-stimulating hormone (TSH), free thyroxine, and free triiodothyronine.

The thyroid gland is a butterfly-shaped organ located in the neck that produces hormones like thyroxine (T4) and triiodothyronine (T3), which are responsible for regulating metabolism and other bodily functions. The production and release of these hormones are controlled by the thyroid-stimulating hormone (TSH), which is produced by the pituitary gland.

A Thyroid Profile Free (FT3, FT4 & TSH) test is used to assess how well your thyroid gland is working and aid in the diagnosis and management of thyroid disorders, such as an overactive thyroid gland (hyperthyroidism) or an underactive thyroid gland (hypothyroidism). Your doctor may advise this test if you show any symptoms suggestive of hyperthyroidism, such as weight loss, nervousness, irritability, increased sweating, and rapid heartbeat, or hypothyroidism, such as weight gain, fatigue, sensitivity to cold, constipation, and dry skin. It is also important for pregnant women to have healthy amounts of thyroid hormones to ensure the healthy development of their babies. Therefore, screening with a TFT-Free test may be recommended for pregnant women.

No special preparations are needed for this test. Usually, you do not need to stop taking your thyroid medication before taking 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 function test results even when the values are normal. Therefore, avoid taking biotin two days before this test.

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

What is Thyroid Profile Free (FT3, FT4 & TSH) used for?

A Thyroid Profile Free (FT3, FT4 & TSH) test is done:

As part of routine health checkups to monitor your overall health.
To evaluate symptoms that can be caused by an imbalance in thyroid hormone levels, such as fatigue, weight loss/gain, hair loss, changes to heart rate, dry skin, and sensitivity to cold.
To diagnose and monitor the treatment of any suspected thyroid disease, such as hypothyroidism, hyperthyroidism, Grave’s disease, thyroiditis, or Hashimoto’s disease.
To detect an underactive thyroid gland in newborn babies.
To evaluate and monitor treatments of other disorders such as thyroid nodules and pituitary or hypothalamus gland disorders.
To investigate the cause of infertility.

What does Thyroid Profile Free (FT3, FT4 & TSH) measure?

Contains 3 tests

A Thyroid Profile Free (FT3, FT4 & TSH) measures the levels of three hormones in the blood, namely triiodothyronine hormone (T3) free, thyroxine hormone (T4) free, and thyroid-stimulating hormone (TSH). T3 and T4 are thyroid hormones that help regulate metabolism and energy levels in the body. On the other hand, TSH is produced by the pituitary gland and stimulates the thyroid gland to produce T3 and T4 hormones. T3 and T4 circulate in the blood in two forms: bound (attached to proteins) and free (does not attach to any protein). The serum levels of the thyroid hormones and TSH have an inverse relationship, i.e., low T4 (as observed in hypothyroidism) and high T4 (as seen in hyperthyroidism) levels are associated with high and low TSH levels, respectively.

Interpreting Thyroid Profile Free (FT3, FT4 & TSH) results

Interpretations

Low T4 and T3 along with a high TSH level indicates hypothyroidism. The most common cause of hypothyroidism is Hashimoto thyroiditis
High T4 and T3 along with low TSH indicate hyperthyroidism. The most common cause of hyperthyroidism is Graves’ disease
Normal thyroxine T4 and T3 along with high TSH usually indicates mild or subclinical hypothyroidism
Normal T3 and T4 along with low TSH indicates mild or subclinical hyperthyroidism

Note: TSH levels show circadian variation (fluctuates during the 24-hour cycle), reaching peak levels between 2 - 4 am and are at low levels between 6-10 pm.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Thyroid Profile Free (FT3, FT4 & TSH)

Frequently Asked Questions about Thyroid Profile Free (FT3, FT4 & TSH)

Q. Why is a Thyroid Profile Free (FT3, FT4 & TSH) test performed?

A Thyroid Profile Free (FT3, FT4 & TSH) test helps evaluate the functioning of the thyroid gland and diagnose or monitor thyroid disorders, such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). This test can help your doctor to make an accurate diagnosis, determine appropriate treatment, and monitor the effectiveness of the treatment over time.

Q. Is fasting required before a Thyroid Profile Free (FT3, FT4 & TSH) test?

No, fasting is not needed before taking this test. However, your doctor will guide you if any special preparation is required.

Q. Can I take a Thyroid Profile Free (FT3, FT4 & TSH) test during pregnancy?

A Thyroid Profile Free (FT3, FT4 & TSH) test along with other tests is usually recommended during pregnancy to measure the levels of thyroid hormones, as thyroid disorders can complicate pregnancy.

Q. Is there any risk associated with a Thyroid Profile Free (FT3, FT4 & TSH) test?

There is generally no risk associated with this test. However, as a needle is used to prick and take a blood sample, rarely you may experience bleeding, swelling, or blood collection under the skin, which is usually self-limiting.

Q. What are some of the common symptoms of thyroid disorders?

Symptoms of thyroid disorders can vary depending on whether the thyroid gland is overactive (hyperthyroidism) or underactive (hypothyroidism). Common symptoms of hyperthyroidism include weight loss, nervousness, irritability, increased sweating, and rapid heartbeat. Whereas, common symptoms of hypothyroidism include weight gain, fatigue, sensitivity to cold, constipation, and dry skin.

Q. What is free T3 and free T4?

Free T3 and free T4 flow through the bloodstream independently. Because these free forms of T3 and T4 can interact with the body’s tissues, they are often considered a better indicator of thyroid function when used alongside other thyroid hormone tests.

Q. Which foods/nutrients can adversely affect my thyroid gland?

The foods/nutrients which are harmful to the thyroid gland include soy foods, such as tofu and tempeh; certain vegetables, like cabbage, broccoli, kale, cauliflower, and spinach; fruits and starchy plants, such as sweet potatoes, peaches, and strawberries; and nuts and seeds, like millet, peanuts, pine nuts, etc.

Q. What additional tests can be performed along with a Thyroid Profile Free (FT3, FT4 & TSH) test?

Several additional tests can be performed along with a TFT-Free test. These tests include a thyroid antibodies test that helps to diagnose autoimmune thyroid disease and distinguish it from other conditions of the thyroid such as Graves’ disease or Hashimoto's thyroiditis, calcitonin test that diagnoses C-cell hyperplasia and medullary thyroid cancer, thyroglobulin test that primarily monitors the treatment and recurrence of thyroid cancer, and thyroxine-binding globulin (TBG) test that evaluates the patients with abnormal levels of T3 and T4.

+ more