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Free Thyroxine Test (FT4 Test)

Dr. Abhishtita MudunuriLast Updated on 9th February 2022

The Free Thyroxine test (FT4 Test) is a blood test to measure the thyroid hormone levels in the body. The thyroid gland is a small butterfly-shaped gland located at the lower part of the throat. Thyroxine regulates energy consumption and plays a crucial role in the growth and metabolism of a person. Thyroxine also regulates:

Mood
Muscle strength
Body weight
Body temperature

The changes in the level of the hormone can indicate abnormalities in the thyroid gland. If you have the following symptoms, the doctor will ask you to order a FT4 test.

Hair loss
Memory issues
Problem with digestion
Sudden weight gain or loss
Bulging of throat
Difficult adjusting to climate changes
Changes in vision, building of eyes, inability to close the eyelids or other eye issues
Skin becoming dry (Hypothyroidism) or too moist (Hyperthyroidism)
Lumps on your neck (may be an indication of thyroid cancer)
Reduced metabolism
Inability to focus and follow things
Increased heart beat rate

Thyroid may also result in the osteoporosis, thyrotoxic crisis, myxedema, red swollen skin, increase in cholesterol and heart disease, mental health deterioration, and depression if untreated for a long time.

What is the FT4 test used for?What is included in the FT4 test?Procedure for FT4 test How to prepare for the FT4 test?Things to consider after the FT4 test is complete What types of infection can the FT4 test detect?How much does the FT4 test cost?How long does it take to get the results for the FT4 test?What do abnormal FT4 test results indicate?

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What is the FT4 test used for?

The FT4 test helps determine the amount of Thyroxine available for use by different tissues in the body. The free thyroxine test is done as a follow-up to get insights into the problems affecting the thyroid gland. This test is conducted when there are abnormal results from the thyroid-stimulating hormone (TSH) test.

What is included in the FT4 test?

The FT4 blood test measures the amount of T4 that is not bound to the proteins in the body and is available for use. This will help ensure if the thyroid gland is functioning well or not. This test is conducted by a certified lab technician.

High levels of FT4 and low TSH can indicate that the thyroid is overactive – hyperthyroidism.
Low levels of FT4 and high TSH can indicate that the thyroid is not active enough – hypothyroidism.
Low levels of both FT4 and TSH can indicate that the pituitary gland is not active enough – hypopituitarism.

Procedure for FT4 test

The FT4 test is conducted to measure the thyroxine level and helps determine the functioning of the thyroid gland. This test can be done by everyone above the age of 5.

A blood sample will be collected from a vein for the test by a certified lab technician.
It is recommended to wear a loose, short-sleeved t-shirt or top for an easy sample collection.
Before the blood collection, an elastic or Velcro band will be tied to the upper arm to apply pressure. Then, the injection site will be cleaned with an antiseptic and the blood sample will be collected using a sterile syringe and stored in a test tube.
The blood sample will then be carefully stored in a case and taken to the lab for analysis. The band will be loosened, and the puncture site will be cleaned and covered with cotton or a small bandage to stop the excess bleeding.
You may feel slight discomfort and stinging when the needle is removed after collecting the blood sample.
The blood sample will be analyzed in our lab equipped with state-of-the-art technology. The blood test results will be available on the MFine app within 24-48 hours of blood collection.

Book an FT4 test to check your thyroxine level!

How to prepare for the FT4 test?

The FT4 test does not require any special preparation. Fasting for 8-12 hours before the test is recommended. You can, however, drink water before the test. It is important to inform the doctor about any medication you are on or if you are pregnant.

Things to consider after the FT4 test is complete

The FT4 test can be part of a regular health checkup to help detect thyroid diseases like hypothyroidism and hyperthyroidism and monitor patients with thyroid disease treatment. The FT4 test may be advised as a routine health check-up in pregnancy.

Please consult a medical professional to interpret the test results. In case you have abnormal results from the FT4 test, you may also need to take T3 and TSH tests and also consider having antithyroid antibodies checked for a more accurate diagnosis.

What types of infection can the FT4 test detect?

The FT4 blood test measures the amount of T4 that is not bound to the proteins in the body and is available for use. This will help ensure if the thyroid gland is functioning well or not. Your doctor may advise a T4 test if a thyroid-stimulating hormone (TSH) test has come back with abnormal results.

High levels of FT4 and low TSH can indicate that the thyroid is overactive – hyperthyroidism.
Low levels of FT4 and high TSH can indicate that the thyroid is not active enough – hypothyroidism.
Low levels of both FT4 and TSH can indicate that the pituitary gland is not active enough – hypopituitarism.

The FT4 test may also be recommended by the doctor if you have the following symptoms indicating thyroid disease:

Increased heart rate
Anxiety
Weight loss
Difficulty sleeping
Tremors in the hands
Weakness
Diarrhea

How much does the FT4 test cost?

The cost of the Free Thyroxine test can differ based on location, but the price of the test ranges between ₹160 and ₹700. You can book the FT4 test for your preferred city below:

City	Average test Cost
Bangalore	500
Mumbai	525
Delhi	600
Kolkata	640
Chennai	470
Hyderabad	500
Pune	570
Ernakulam	375
Trivandrum	400
Warangal	450
Tirupati	400

*Disclaimer: The value varies based on location, time, and your preferred lab partner.

How long does it take to get the results for the FT4 test?

You can expect to get the results for the FT4 test within 24 to 48 hours after the sample is collected. There may be a change in time for receiving the test results based on the city and time.

What do abnormal FT4 test results indicate?

The normal T4 range in adults can range from 0.9 to 1.9 nanograms per deciliter (ng/dL). Free T4 levels vary in children according to age. If the T4 level is outside the normal range, please consult a doctor to interpret the results and determine a treatment plan.

Along with T4, T3 is also a major hormone produced by the thyroid gland that helps regulate the body’s metabolism.

The FT4 blood test measures the amount of T4 that is not bound to the proteins in the body and is available for use. This will help ensure if the thyroid gland is functioning well or not. Your doctor may advise a T4 test if a thyroid-stimulating hormone (TSH) test has come back with abnormal results.

High levels of FT4 and low TSH can indicate that the thyroid is overactive – hyperthyroidism.
Low levels of FT4 and high TSH can indicate that the thyroid is not active enough – hypothyroidism.
Low levels of FT4 and TSH can indicate that the pituitary gland is not active enough – hypopituitarism.

Disclaimer: Please consult your doctor for interpreting the test reports.

Is the FT4 test definitive?

The FT4 test is not definitive but can indicate the functioning of the thyroid gland. By combining this test with T3 and TSH, it will provide a better understanding of thyroid functioning. The FT4 test helps detect thyroid diseases like hypothyroidism or hyperthyroidism and monitors patients with thyroid disease treatment. T3 and T4 levels may automatically increase during pregnancy and may be included as part of a routine checkup.

How to read the FT4 report?

The normal T4 range in adults can range from 0.9 to 1.9 nanograms per decilitre (ng/dL). Free T4 levels vary in children according to age. Those who take medication for modifying the metabolism of the thyroid hormone or those with pituitary or thyroid disease may have a different normal FT4 range. Please consult a doctor for an accurate diagnosis and treatment plan.

Book an FT4 test to check your thyroxine level!

Why book the FT4 test?

To have a better understanding of the thyroid functioning.
To help detect thyroid diseases like hypothyroidism or hyperthyroidism.
To monitor patients with thyroid disease treatment.
To monitor thyroxine levels during pregnancy as part of the routine checkup.
To confirm whether you have thyroid tumour incase of having lumps on your neck.

FT4 test at home – how does it work?

The FT4 test is just like any other blood test. A lab technician visits your home when you book your tests through the MFine app. The lab technician first cleans the arm and then inserts a syringe into a vein. The required amount of blood is then taken into a vial. The lab technician then removes the needle and places cotton wool or a bandage over the prick.

Are there any risks involved with the FT4 test?

A T4 test doesn’t have any specific risks, apart from the slight discomfort and pain at the injection site from where the blood is drawn for the sample. But this should go away soon. If you are taking any medications which delays blood clotting, inform your doctor before giving the blood sample.

What can affect the results of the FT4 test?

T3 and T4 levels may automatically increase during pregnancy and may be included as part of the routine checkup. Those who take medication for modifying the metabolism of the thyroid hormone or those with pituitary or thyroid disease may have a different normal FT4 range.

Book a FT4 to check your thyroid level!

Our Trusted Lab Partners for Free Thyroxine Test

MFine Diagnostics

Starting at

₹300

Wellness Pathcare

Starting at

₹300

Thyrocare

Starting at

₹300

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Frequently Asked Questions | FAQs

Is the lab technician coming for the FT4 sample collection vaccinated?

Yes. Our lab technicians are fully vaccinated. Further, they also ensure safety throughout by wearing a mask, gloves, and frequently sanitising themselves during the sample collection.

Does MFine provide the interpretation for the results along with the reports?

Yes, MFine provides the interpretation for the result along with the reports. You can also avail a free medical consultation with a doctor to understand your reports accurately. The doctor will also advise and prescribe medicines, if required, based on the results.

How can I download my FT4 test report?

Login to MFine
Go to your profile
Click on Attachment and Reports
Click on Lab Report
Download the report

Are there any discount offers running on the FT4 test?

Usually, you can avail of up to a 50% discount on the FT4 test through MFine. However, the discount and test price may vary based on lab partner and location.

Is it normal to have high T4 levels during pregnancy?

Yes, T3 and T4 levels may automatically increase during pregnancy and thyroid tests may be included as part of the routine checkup.

Why do I need a Free Thyroxine test?

A free thyroid test helps you have a better understanding of thyroid functioning, helps detect thyroid diseases like hypothyroidism or hyperthyroidism, allows monitoring of patients with thyroid disease treatment, and helps manage hyperthyroidism or hypothyroidism during pregnancy.

My FT4 levels are normal. Does that mean I have no thyroid issues?

The FT4 test is not a definitive test, but an indicative one. Along with T4, T3 is also a major hormone produced by the thyroid gland that helps regulate the body’s metabolism. If you have normal FT4 levels but have symptoms that may be associated with thyroid abnormalities, you may be advised to take the T3 and TSH tests as well to ensure if the thyroid gland is functioning properly. You may also need to have antithyroid antibodies checked for a more accurate diagnosis in case of abnormalities.

What is Hypothyroidism?

When the thyroid gland makes less-than-required thyroid hormones, you may experience hypothyroidism. This is indicated by low levels of FT4 and high TSH levels. Some of the symptoms of this condition can include weight gain, decreased energy, constipation, chills, and slowed thinking.

What is Hyperthyroidism?

When the thyroid gland produces excessive thyroid hormones, you may experience hyperthyroidism indicated by high levels of FT4 and low TSH levels. Symptoms of hyperthyroidism include unintentional weight loss, restlessness, tremors, palpitations, frequent bowel movements, and sleep disruptions.

What is Thyroiditis?

Thyroiditis is a condition that could be due to either hyperthyroidism or hypothyroidism that results in the inflammation of the thyroid gland. There are many symptoms that will indicate the thyroiditis condition in the patient. But the common symptoms are irregular menstruation, swelling of eyes or throat, fatigue, muscle weakness, unintentional weight changes, dryness of the skin and hair, tremors, and elevated heartbeat.

What are the common symptoms of thyroiditis?

Hair loss, memory issues, problems with digestion, sudden weight gain or loss due to hormonal imbalances, bulging of the throat, difficulty adjusting to climate changes, changes in vision, bulging of the eyes, the inability to close the eyelids or other eye issues, skin becoming dry (Hypothyroidism) or too moist (Hyperthyroidism), lumps on your neck (may be an indication of thyroid cancer), reduced metabolism, inability to focus, remember or follow things, irregular menstruation.

Disclaimer: The content is uniquely informative and is meant for educational use. Kindly use the content only in consultation with an appropriate certified or registered healthcare provider.