What are Healthy Thyroid Levels?

Iodine is the base ingredient for production of thyroid hormones by the thyroid gland. It is absorbed from the ingested foods, and cannot be synthesized naturally. Two forms of thyroid hormones are produced by the thyroid gland, viz. T3 (triiodothyronine) and T4 (thyroxine). Of these, T3 is the active form, and contains three atoms of iodine. On the other hand, T4 is the inactive type with four iodine atoms, which further gets converted to T3 in various parts of the body.



The level of thyroid-stimulating hormone (TSH) is used as a reference for determining, whether a person has healthy thyroid levels or not. Laboratory blood test procedure is conducted to examine levels of TSH produced by the pituitary gland. It does the function of promoting thyroid gland to secrete thyroid hormones. Ideally, TSH falling in the range 0.5-5.0 mIU/L (milli-international units per liter) is considered normal or healthy, and the individual is considered free of thyroid diseases. But, the newly updated normal TSH levels are considered as 0.3-3 mIU/L.



Lower TSH signifies that the gland is hyperactive and produces excess hormones. On the contrary, increased TSH levels is a warning sign that the thyroid gland is not responding properly as it should, or the gland is underactive, resulting in low thyroid hormone production. If required, the doctor will proceed for a series of other thyroid hormone tests. The following info is all about thyroid hormone tests, and respective test readings that are considered normal or healthy for adults.