T4 is a hormone of the thyroid gland. Basic role of this gland is to produce T3 and T4, its main hormones. Thyroid hormones have a lotof roles, including growth and metabolic functions. Thyroid function isregulated by the mechanism that originates in hypophysis. The hormone thatregulates the secretion of T3 and T4 is TSH, hormone that directly stimulates the production of those hormones. Beside, TSH, there is also TRH, which actuallycontrols the levels of TSH and is produced in hypothalamus.
Regulation of secretion is acquired through the regulationof two opposite functions, stimulation of TRH and inhibition of T3 and T4. T3is very important when it comes to thermal genesis and it affects themetabolism of cells. Normally, in circulation there are 99,95 percent of T4 and99,50 percent of T3 connected to TBG (thyroglobulin). So, only small amountsof T4 and T3 are in active, free form. Medical problems that are related to themetabolism of thyroid glands are presented with the change in the secretion ofT3 and T4 and also with the change in the structure of the gland itself.
Medical problems related to thyroid gland
Struma is a condition that is characterized by decreased levels of thyroid hormones, which ultimately leadsto the increase of TSH in hypophysis and also to the enlargement of the gland. Signsinclude changes in the throat area, irritable coughing and similar problems. If the thyroid gland becomes too big, it might pressure blood vessels in neck area,veins especially.
Hyperthyroidism is induced by the increased secretion of thethyroid hormones. Within this basic condition, there are several medicalconditions, including those that are caused by autoimmune reaction, there isalso toxic struma (antibodies are found for thyroid hormones and thyroglobulin,which serves as a protein carrier). Toxic struma is dangerous because eyeproblems might occur in a form of retraction of eye lids. Also, the accumulation offat tissue behind the eyeball might happen, and eyes protrusion too Opposite problem is hypothyroidism with the decreased rateof basal metabolism as one of the main symptoms.
To be able to treat the condition, a proper diagnosis has tobe established. Products made from thiourea are used for dealing with toxicstruma. Medicaments are actually used for all forms of problems that happenbecause of the changed levels of thyroid hormones. Iodide therapy can also be used, and in some cases, surgery might be needed.