Thyroid is an important gland which secretes hormones that play a major role in growth and maturation of the human body as well as metabolism. Several vital body functions are regulated by this gland and its hormones and their levels vary as per changing requirements during different periods of life cycle such as growth, pregnancy or even during weather changes (Extreme hot or cold climates)
This gland is butterfly-shaped located in the front side of the neck attached to the lower part of the voicebox (or larynx) and to the upper part of the windpipe (or trachea).
The hormones produced by the thyroid gland are:
- Tri-iodo-thyronine (T3)
- Tetra-iodo-thyronine (T4)
Iodine
As indicated by the name, these hormones contain iodine. Iodine, being a chief component of the thyroid hormones, is an essential nutrient required for proper functioning of the thyroid gland. We know that iodine is naturally present in drinking water and soil. However, the climate changes resulting in glaciations, flooding, changing course of rivers and deforestation are causing leaching of the iodine from the soil. This iodine deficient soil leads to low iodine content of the grains and vegetables grown in it and finally an iodine deficient diet of humans as well as animals. Low iodine levels in the diet lead to disorders such as goitre and cretinism.
We talked about T3 and T4, but there is also TSH , right? Blood test for detecting thyroid function include all three , in fact sometimes only TSH levels are estimated.
TSH – Thyroid Stimulating Hormone is produced by the pituitary gland located at the base of the brain. The hypothalamus (small part of the brain) signals the pituitary gland to produce TSH via its messenger TRH (thyrotropin releasing hormone).
When thyroid hormone levels fall below normal, then the hypothalamus release TRH which in turn signals the pituitary to release TSH. TSH instructs the thyroid gland to secrete enough thyroid hormones to fulfill body’s current requirement.
In normal healthy individuals, the balance of these hormones is maintained in perfect harmony and adapts to changing requirements at different phases. But, in individuals who have some form of thyroid disorders all aspects of growth and development are adversely affected.
The two main disorders commonly seen in individuals are:
- Hypothyroidism – Associated with poor production of thyroid hormones
- Hyperthyroidism- Associated with increased production of thyroid hormones.
So too much or too little of his hormone is dangerous. Often thyroid disorders have generalized symptoms but it is indeed prudent to rule out this cause before it gets too late. Especially in infants, the thyroid levels should be checked at birth itself as prolonged deficiency or excess can have irreversible life long damaging effects on growth, cognition and overall health.
References:
http://www.thyroid.ca/thyroid_gland.php
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072572/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3818611/
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