Brianna Laplante

The thyroid gland is a small gland, usually weighing less than one ounce, located just below the larynx.  It is made up of two lobes that lie along the trachea which are joined together by a narrow band of thyroid tissue, called the isthmus.  During development inside the womb, the thyroid gland originates in the back of the tongue, but it normally moves to the front of the neck before birth.  In rare cases, it fails to move properly and is located high in the neck or even in the back of the tongue.  This abnormal condition is called lingual thyroid.  At other times, it may migrate too far and end up in the chest. 

The function of the thyroid gland is to take iodine, which is found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3).  Thyroid cells are the only cells in the body that can absorb iodine.  These cells combine iodine and the amino acid tyrosine to make T3 and T4.  T3 and T4 are then released into the blood stream and transported throughout the body where they control metabolism.  Every cell in the body depends upon thyroid hormones for regulation of their metabolism.  The normal thyroid gland produces about 80% T4 and about 20% T3, however T3 is about four times the hormone strength of T4.

 The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain.  When levels of T3 and T4 drop too low, the pituitary gland produces thyroid stimulating hormone (TSH) which stimulates the thyroid gland to produce more hormones.  Under the influence of TSH, the tyroid will manufacture and secrete T3 and T4, raising their blood levels.  The pituitary gland senses these changes and responds by decreasing its TSH production. 

Thyroid cancer is not very common.  Thyroid cancer only accounts for 1.2% of all new cancers in the U.S. annually! The four types of thyroid cancer include papillary, follicular, medullary, and anaplastic.  September is thyroid cancer awareness month.

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