FT4-Free Thyroxine Serum Test in Kalyan

T4 (thyroxine) circulates in body in a bound form with thyroxine-binding globulin and albumin.  Less than 0.3% of the total T4 is free fraction (FT4) and is the active form. Free T4 test measuring free T4 levels, more accurately reflect how the thyroid gland is functioning when checked with TSH.
Thyroid hormones are essential for growth and metabolism. Following are the symptoms of hyperthyroidism: weight loss, rapid heartbeat, tremors, sweating, anxiety, increased sensitivity to heat, etc. 
Whereas patients with hypothyroidism suffer from weight gain, fatigue, slow heart rate, increased sensitivity to cold, depression, dry and thin hair etc.

A thyroxine test or T4-Free Thyroxine Serum Test is used to diagnose thyroid conditions. The hormones produced by the thyroid gland help in controlling the way our body utilizes energy. Our thyroid is a tiny, butterfly-shaped gland. It is located at the base of our throat. The thyroid hormone also affects our weight, muscle strength, body temperature, heart health, and even our mood. When it comes to children, a thyroid disorder can affect their growth as well.

A T4-free thyroxine test measures the amount of thyroxine hormone in our blood. In case the level of T4 hormone in our blood is too little or too much, it is an indication that we may have thyroid disease.

T4 levels are measured using two different tests:

• A free T4 test is used to measure the T4 levels directly in the blood. As per medical experts, this test provides more accurate information in comparison to the total T4 test.
• The total T4 test is used to check the level of both free and found T4 together. This method is considered to be less accurate to check the working of our thyroid gland.

  The Free T4 test is done to:

1. To diagnose thyroid disorders: The free T4 test is often used to evaluate thyroid function and to diagnose thyroid disorders such as hypothyroidism or hyperthyroidism.
2. To monitor thyroid function: The free T4 test may be ordered to monitor thyroid function in people who are being treated for thyroid disorders.
3. To assess the effectiveness of thyroid medication: If someone is taking thyroid medication, their free T4 levels may be checked to make sure the medication is working effectively.
4. To assess fertility issues: The free T4 test may be ordered as part of an infertility workup, as thyroid disorders can affect fertility.
5. To evaluate symptoms such as fatigue, weight gain, or weight loss: If someone is experiencing symptoms such as fatigue, weight gain, or weight loss, the free T4 test may be ordered to help diagnose or rule out a thyroid disorder as a possible cause.
6. To monitor pregnancy: The free T4 test may be ordered during pregnancy to monitor thyroid function, as thyroid disorders can affect the health of the mother and the developing fetus.

Written by: Dr Vishal Wadhwa, M.D, D.N.B Microbiology, Medical Affairs