The normal range for total thyroxine, abbreviated as T4, is 5.4 to 11.5 micrograms per deciliter in adults, while the normal adult range for total triiodothyronine, abbreviated as T3, is 80 to 200 nanograms per deciliter, according to WebMD. In adults, thyroid-stimulating hormone, known as TSH, should be between 0.4 and 4.2 microunits per milliliter.
Children have different normal ranges for these tests, notes WebMD. For a newborn, a normal T4 range is 11.8 to 22.6 micrograms per deciliter, and a normal TSH range for a newborn is 1 to 39 microunits per milliliter. Older children should have T4 in the range of 6.4 to 13.3 micrograms per deciliter, and a TSH range of 0.7 to 6.4 microunits per milliliter. Children ages 1 to 14 should have a T3 level of 105 to 245 nanograms per deciliter, while people from the ages of 12 to 23 should have a normal T3 range of 82 to 213 nanograms per deciliter.
The thyroid glands produce T3 and T4 hormones, explains WebMD. In children under the age of 3, these hormones are essential for brain development. Older children also need to receive the correct amount of these hormones to aid in proper body development. In adults, T3 and T4 hormones regulate the metabolism. Low T3 and T4 values indicate hypothyroidism, while high values indicate hyperthyroidism.
The pituitary gland produces the TSH hormone, which triggers the thyroid to make T3 and T4, states WebMD. Low TSH values indicate possible hyperthyroidism, damage to the pituitary gland, a first-trimester pregnancy or an excess of thyroid-stimulating medication. High TSH values can indicate hypothryroidism, a pituitary gland tumor or that an insufficient amount of thyroid medication is in the bloodstream.