T4 ELISA

The thyroid hormone, thyroxine (T4) is produced by
the thyroid gland. An important component in the
synthesis is iodine. The major form of thyroid
hormone in the blood is thyroxine (T4). Thyroxine is
converted to the active T3 (three to four times more
potent than T4) within cells by deiodinases (5'-
iodinase).
Thyroxine-binding globulin (TGB) is the major carrier
protein for circulating thyroid hormone. Only a very
small fraction of the circulating hormone is free
(unbound) - T4 0.03%.
The thyronines act on the body to increase the basal
metabolic rate, affect protein synthesis and increase
the body's sensitivity to catecholamines (such as
adrenaline) by permissiveness. The thyroid hormones
are essential to proper development and
differentiation of all cells of the human body. These
hormones also regulate protein, fat, and carbohydrate
metabolism, affecting how human cells use energetic
compounds. Numerous physiological and
pathological stimuli influence thyroid hormone
synthesis.
Thyroid hormones act through an unknown
mechanism to inhibit neuronal activity; one of the
effects is the reduction of the body temperature.
Thyrotoxicosis or hyperthyroidism is the clinical
syndrome caused by an excess of circulating free
thyroxine, free triiodothyronine, or both.
Both T3 and T4 are used to treat thyroid hormone
deficiency (hypothyroidism).