The '''thyroid''' (from the [[Greek]] word for door) is a small [[endocrine ]] ([[hormone]]-producing) organ located in the front of the neck just below your [[larynx ]] ("Adam's apple"). The thyroid is responsible for regulating many processes in the human body.
==Function==
The thyroid processes '''[[iodine]]''' into two hormones: [[thyroxine ]] (T4) and [[triiodythyromine ]] (T3). These two hormones control [[metabolism]]. It also produces [[calcitonin]], which is necessary for [[calcium ]] absorption. The thyroid is controlled by the [[pituitary gland]].
The pituitary releases '''T'''hyroid '''s'''timulation '''h'''ormone (TSH) in response to T3 and T4 levels circulation in the blood. If there is an excess of T4, TSH production is diminished; if there isn't enough T4, TSH production is increased.
==Iodine==
Iodine, which is found in many foods, is the essential nutrient in thyroid function. If one does not consume enough iodine, the thyroid becomes enlarged, which leads to a [[goiter]]. This is the reason that we see ''iodized'' salt—to prevent growth deficiencies related to a lack of iodine in the diet.
==Hypo/hyperthyroid==
Hypothyroidism is a lack of T3/T4 in the blood stream;hyperthyroid is an excess. The chief diagnostic tool for these illnesses is that TSH level. The TSH level is inversely proportionate to the level of thyroid function (i.e. a high TSH level means an hypoactive thyroid). Signs and symptoms include:
===Hypothyroid===
*Paleness
*Weight gain and/or water retention
*[[Bradycardia ]] (slow heart rate)
Treatment for hypothyroid involves thyroid-hormone replacement therapy ([[thyroxine]]).
===Hyperthyroid (Graves disease)===