Frequently asked question: Are both thyroid hormones, T4 and T3, active?

No. Although the thyroid gland produces much less T3 than it does T4, T3 is, in fact, the active form of the hormone. T4 is the inactive form of thyroid hormone and becomes active only when it is converted to triiodothyronine (T3).

Also interesting

What does the thyroid gland do?

The follicular cells produce hormones, mainly thyroxine (T4) and a small amount of triiodothyronine (T3). Both hormones …

How is the thyroid gland controlled?

The pituitary, an endocrine gland in the brain, controls the thyroid gland and, in doing so, ensures that the hormones p…

What are the reasons the thyroid gland does not always work as it should?

The thyroid gland does not function properly, for example, if something went wrong during the development and migration …

Is it always the entire thyroid gland that is enlarged?

If benign thyroid nodules are caused by toxic multinodular goiter, what does that mean?

What is T3?

What is T4?

How is thyroid hormone produced?

What are the possible causes of hypothyroidism that starts during childhood or adolescence?

What is congenital hypothyroidism (CH)?

Relevant medical information

No answer for your question?

Ask your question about Thyroid Disease to an expert

Thyroid Hormone

Are both thyroid hormones, T4 and T3, active?

How is thyroid hormone produced?

How many different types of thyroid hormone are there?

What are the effects of thyroid hormone on respiration?

What are the effects of thyroid hormone on the heart?

What are the effects of thyroid hormone on the metabolism?

What are the effects of thyroid hormone on the nervous system?

What are the effects of thyroid hormone on the skeletal system?

What does thyroid hormone do?

Other subjects

A Nodule in the Thyroid Gland

Abnormalities of the Thyroid Gland

Diagnosing Thyroid Disorders

Enlarged Thyroid Gland (Goiter)

Hyperthyroidism

Hypothyroidism

Thyroid Gland

Thyroid Hormone