Thyroid T4 refers to tetraiodothyronine and FT4 refers to serum free thyroxine. High T4 and FT4 may be caused by diffuse toxic goiter, autonomous high-functioning adenoma of the thyroid gland and subacute thyroiditis.
1. Diffuse toxic goiter: the body develops specific antibodies, which stimulate the hypothalamus, causing thyrotropin receptor cells to become overactive, and the increased secretion of thyrotropin can lead to an increase in the production of thyroid hormones, resulting in high T4 and FT4.
2. Thyroid autonomous hyperfunctioning adenoma: it is mostly due to the uncontrolled secretion of thyroid hormone by the adenoma, which causes high T4 and FT4, and is often accompanied by symptoms of hyperthyroidism, such as excessive sweating and irritability.
3. Subacute thyroiditis: Due to the destruction of the thyroid follicles, the thyroid hormones stored therein are released into the circulation, which can cause elevated T4 and FT4, also known as hyperthyroidism, and is often accompanied by mild-to-moderate enlargement of the thyroid gland, localized tenderness and other uncomfortable symptoms.
Thyroid T4, FT4 high can also be seen in other causes, we recommend that the patient under the guidance of the doctor to improve further examination, a clear diagnosis.