T4-Total Thyroxine Serum Test

T4 (thyroxine) circulates in body in a bound form with thyroxine-binding globulin and albumin.
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.

The T4-Total Thyroxine Serum test is used to measure the level of T4 hormone in our blood. Also known as thyroxine, this hormone is produced by the thyroid gland and helps in controlling our growth and metabolism. The T4-Total Thyroxine Serum test is done to evaluate how well our thyroid gland is working.

Two blood tests are performed to check the levels of T4 in our blood. These include:

• Total T4: A test used to measure the total amount of thyroxine in our blood, including the hormones attached to the blood proteins used for transporting it through the bloodstream.
• Free T4: A test used to measure the level of thyroxine that is not attached to the blood proteins and is affecting the functioning of various body cells.

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