Thyroxine - Levels, Side effects, Function, Test, Symptoms, Treatment

Thyroxine is the name of the hormone secreted by thyroid gland which does the work of metabolic activities. It also controls the rate of oxidation level in the cells. Thyroxine hormone contains 65% iodine which is necessary for the production of T3 and T4 (tyrosine) hormones. When there is deficiency of iodine it will automatically reduce the production of T3 and T4 hormones causing goiter. When there is increase in thyroxine this leads to a condition called hyperthyroidism.

Hence the thyroxine hormone should be at the optimal level for normal health.

Function

Thyroid hormone is responsible for circulating the protein content in the blood. Most of the hormones will contain certain amount of protein and only some of them are free circulating still biologically active.

Hence thyroxine carries out the job of plasma transport to all the cells in your body. Thyroid hormone cannot get through cell membranes like that of lipophilic substances.

The primary function of thyroxine is to control the metabolic rate in our body. It helps to regulate the bone growth in combination with growth hormone. It further acts to increase the body’s sensitivity towards catecholamine.

Thyroid hormone is absolutely necessary for normal development of cells and they are vital in controlling the metabolism of proteins and fats in your body. In addition, it also controls various physiological activities and help in heat generation in the body.

In animals, thyroxine is responsible for hibernation period and it controls the molting behavior in birds.

Excess of Thyroxine

In one deciliter of blood, there should be 4.5—11.2 mcg of thyroxine in blood. This is considered as standard level of this hormone and anything lesser than and higher than this normal level is dangerous.

When thyroxine level crosses the limit and circulates in excess, this condition is called hyperthyroidism (Grave’s disease). Similarly, when the level is below 4.5 then this condition is called hypothyroidism, which arises due to deficiency of thyroxine. People with low level of thyroxine will have dry skin with white patches, slow reflexes, slow pulse rate, enlarged heart and slow speech. Goiter is a condition of low thyroxine level in blood and such people will have rapid weight gain, weakness, joint pain and stiffness in joints. They will also have symptoms of difficulty in concentration, loss of memory and sleeping sickness. They are more prone to heart attack and stroke than normal individuals.

In hyperthyroidism, the thyroxine per deciliter crosses the normal range which may cause serious health complications. People with excess of thyroxine will have germ cell tumors, Grave’s disease, and trophoblastic disease. They would sweat a lot on the entire body and their skin will be moist almost all the time. Further their nails will be rising up in the edges signifying Plummer’s nail condition. Their pulse rate will be very high with increased palpitation.