The Thyroid gland is something that produces two major hormones in your body. T3 and T4, which are names Triodothyronine and Tetraiodothyronine, respectively. T3 is more effective, but mostly T4 is released into your bloodstream.
Thyroid Hormones, when they are released can increase your Metabolism by raising the rate of oxygen consumption in most tissues, exluding brain spleen and gonads. Their action is by increasing the activity of a protein in the membrane of cells called Na/K ATPase. Also heat is generated more actively.
The Central nervous system will mature as a result of proteins synthesized in response to thyroid hormones.
General growth including in bones is increase, and most effects of metabolism are increased.
In metabolism, the effect of Thyroid hormones can increase absorption of sugar from the blood, breakdown of sugar storage, breakdown of fat in your boy, and increase the production of proteins in your body. All these effects of metabolism help to induce growth and maturation of all sorts of tissues, and the increased functional activity in Metabolic pathways utilizes the use of stored energy. They help your body use up stored energy and prevent storage in the first place.
The most important effect is likely the increase Heart rate in response to thyroid hormones.
Hyperthyroidism, is a pathological condition in which, either the feedback mechanism to lower thyroid hormones is disturbed or by some over active release of hormones like TRH or TSH which are the promoters for release of Thyroid hormones.
Effects of hyperthyroidism are dramatic in terms of symptoms. Loss of weight, regardless of large food intake, excessive sweating and heat production due to excessive oxygen consumption.
Hypoparathyroidism is the opposite condition, where Thyroid hormones are at pathologically low levels. Often the cause of this is an autoimmune disorder which can cause the destruction of the thyroid gland because your immune system is killing of your own cells. In this case the symptoms are opposite but much more unnerving. You can gain weight due to lowered metabolic rate, regardless of how little you eat. Movement and thinking is slowed, speech may be slurred, hair can be lost. On top of all of that menstrual function can be affected.
The most awkward cases are noticed in GOITER where patients can’t produce the hormones because of for example insufficient Iodine in their diet. This is notable in underdeveloped economies, where use of table salt is less common. The effects can turn to mental retardation and overgrowth of the thyroid gland, as a response by the body attempting to stimulate the thyroid to produce more hormones, regardless of the fact that it is unable to do so.