Learn about T4

What Is Thyroid Hormone Replacement Therapy?

Hypothyroidism is a condition classified by an under-active thyroid gland—when the thyroid does not produce enough hormones.

Synthetic T4 Supplements for Hypothyroidism

Synthetic forms of the thyroid hormone T4 are generally called levothyroxine, and they are considered the standard treatment for hypothyroidism.

Animal Thyroid Supplements for Hypothyroidism

Though synthetic thyroid hormones are the preferred medication for hypothyroidism today, animal thyroid hormones (also known as desiccated, or dried, thyroid extract) were once the standard treatment. In fact, they were the only treatment available.

Hypothyroidism Glossary

Animal (Desiccated) Thyroid Extract A crude preparation made of animal, usually pig, thyroid glands. It was the first available source of thyroid hormone (thyroxine). It is still available today, but synthetic thyroid supplements are the preferred hypothyroid treatment.

An Overview of the Thyroid

Thyroid Essentials

Hyperthyroidism: Overactivity of the Thyroid Gland

There are several causes of hyperthyroidism. Most often, the entire gland is overproducing thyroid hormone. This is called Graves' disease. Less commonly, a single nodule is responsible for the excess hormone secretion.

Diagnosing Hyperthyroidism: Overactivity of the Thyroid Gland

The actual diagnosis of hyperthyroidism is easy to make once its possibility is entertained.