T3-Total Tri Iodothyronine Serum Test

T3 (triiodothyronine) 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.

A T3 test is mainly performed to measure the levels of Triiodothyronine in the blood. It is one of the two major hormones that are made by the thyroid gland. The other hormone is thyroxine (T4). The thyroid gland is located near the throat. The two hormones, T3 and T4, work together to regulate how the body uses energy. They also play a vital role in enhancing body weight, muscle strength, temperature and the functioning of the nervous system.

Any abnormality in the results of a T3 test may indicate signs of thyroid disease. T3 is an active form of thyroid hormone. This means that it impacts all the cells in the body. Together, T4 and T3 play an active role in regulating the body’s metabolic rate, digestive function, brain development, bone maintenance and muscle control.

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