Triiodothyronine (T3) Test

Triiodothyronine (T3) Total Test measures the total levels (both free and bound forms) of Triiodothyronine (T3) hormone in the blood. For the human body to function, it needs energy. This energy is generated from food by the process of Metabolism. Metabolism is assessed by the basal metabolism rate (BMR). The thyroid gland secretes hormones that have a direct impact on the BMR levels. T3 and T4 hormones by the thyroid gland play a vital role in metabolism, growth and development. The T3 test is used in the diagnosis of clinical as well as subclinical thyroid disorders. The thyroid gland is an endocrine gland present in the human body. It is situated at the lower front part of the neck. It regulates bodily functions such as metabolism, energy production and mood. The thyroid gland produces T3 and T4 under the effect of thyroid-stimulating hormone (TSH). T3 and T4 hormones are produced by the thyroid gland using iodine obtained from meals. T4 or Tetraiodothyronine is generated entirely by the thyroid gland. T3 is Triiodothyronine, which is created by reducing the iodine from T4. T3 and T4 are present in the blood in bound and free form. Two blood tests that are part of a T3 test report are Total T3 and Free T3. Total T3 measures the total amount of Triiodothyronine in the blood. This T3 test report includes the amount of T3 bound to blood proteins. These proteins help in the transport of the hormone. Free T3 test report measures the thyroxine that is not bound to proteins. Free T3 is the portion of T3 that is available to other body cells for functioning. T3 hormone becomes abnormal before T4 and returns to normal levels later than T4. Hence, the free triiodothyronine (FT3) test determines whether the thyroid gland is functioning optimally or there is some thyroid disorder. The T3 test is more useful to detect hyperthyroidism. If the symptoms point to a thyroid problem, the doctor may prescribe a T3 test. Thyroid disorders can have severe complications. The proper diagnosis and timely treatment are essential to avoid these complications. Thyroid diseases are endemic in certain parts of India where there is a lack of naturally available iodine. Goitre or hyperthyroidism can develop due to a lack of iodine in the diet. T3 and T4 are common deficits in the sub-Himalayan region. It is a crucial test to have during and before pregnancy since poor thyroid function might impact the growth of the foetus.