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All about the thyroid: What is it?

The thyroid gland is a very small and butterfly-shape located in front of the neck below the Adam’s apple or laryngeal prominence, the gland wraps partly around the trachea or windpipe. It is composed of units called follicles, and in the center of these follicles is colloid filled with storage protein called thyroglobulin, which is a huge glycoprotein. The follicles secrete colloid and the thyroid hormones are made within the follicles. The thyroid depends on two main hormones that are secreted from the thyroid gland: thyroxine (T4) and triiodothyronine (T3). These hormones are highly important in regulating basic bodily functions and most organs in the body. T3 is the most biological activity, being more active than T4 in affecting the metabolism of cells; it represents 99.9% of thyroid hormones activity. A large amount of T4 gets converted into T3 (the feel good hormone) in the liver, gut and in other peripheral tissues throughout the body.

About 20 million people are suffering with thyroid issues and about 60% are undiagnosed. It is highly more common in women than in men. This could be due to the fact that some thyroid diseases are autoimmune diseases, and more women have autoimmune conditions than men. Hypothyroidism is a condition where the thyroid gland is under-active and doesn’t make enough of thyroid hormones in the bloodstream. Hashimoto’s Thyroiditis is the most common form of hypothyroidism. Thyroiditis means an inflammation of the thyroid gland. Hashimoto’s is an autoimmune condition where your immune system mistakenly attacks your thyroid gland. Hyperthyroidism is a condition where the thyroid gland is over-active and makes surplus amount of thyroid hormones in the bloodstream. Grave’s disease is the most common form of hyperthyroidism; it is an autoimmune condition that causes an enlarged thyroid gland or goiter due to an excessive amount of thyroid hormones being produced.

The human body relies on thyroid hormones to ensure the proper functioning of cells, such as regeneration, proteins production, glucose storage, creation of new enzymes, and synthesizing DNA. If the thyroid produces in excess or in deficit, these essential processes will not continue to work properly; most tissues in the body are affected and influenced by the thyroid gland and thyroid hormones. The thyroid runs our metabolism, heart rate, mood, blood pressure, and body temperature to name a few.

The glands that regulate the activity of thyroid hormones are the hypothalamus and the pituitary gland. The hypothalamus and pituitary gland are connected to each other at the base of the brain. The hypothalamus secretes its hormone thyrotropin-releasing hormone (TRH) in response to a reduced level of circulating thyroid hormones, TRH goes to the pituitary gland. The pituitary gland produces a hormone called thyroid stimulating hormone (TSH), which tells the thyroid gland to produce the right amount of hormones. The TSH is released into the bloodstream to activate the thyroid cells, which then secretes majority of T4 and and little bit of T3 into the peripheral tissues. TRH and TSH are to ensure that hormone availability remains constant in the internal body environment, maintaining the body’s homeostatic levels of T4 and T3. The entire thyroid system is based on a negative feedback loop. When the pituitary produces enough TSH this causes negative feedback loop, signaling the cells of hypothalamus to turn off TRH. Without TRH none or little TSH is produced. The pituitary gland also shuts down when there are signs that there is too much T4 or T3 hormone production and causes a negative feedback. Conversely, when there is not enough T4 or T3  being produced and circulating throughout the body then hypothalamus increases TRH, which increases TSH. 

Iodine is essential for the thyroid gland; it is required for the cells to produce T4 and T3 since each of these hormones contain T4 and T3 iodine, the thyroid gland removes iodine from the blood, which then enables the production of  the two hormones. The iodine goes into the thyroid cells and it will combine with amino acids called tyrosine to form a large thyroglobulin molecule, which is found in the center of the follicles. Iodine mostly comes from our diet, such as seafood, bread, salt, or other iodine-rich food. If the thyroid gland does not have a sufficient amount of iodine it is unable to produce an adequate amount of the thyroid hormones, which can have serious health consequences. Iodine deficiency is mostly found in inland areas where people do not have access to iodine-rich soils both of which are readily available in coastal areas. There are other factors besides iodine that contribute to proper production of the thyroid hormones are nutrients, such as iron, tyrosine, zinc, selenium vitamin E, B2, B6, C and D.

Thyroid hormones have a major role in brain development. Thyroid hormone are also very crucial for normal body growth. The importance of thyroid hormones for healthy growth begins even before birth, being critical to the fetal development. During pregnancy, the fetal thyroid begins to grow around the first trimester. However, it is the second trimester where the developing fetus start making its own T4 and T3, but still relies on the maternal hormones throughout pregnancy. During this vital brain development stage, thyroid hormones play an important role. Crucial brain development begins before the fetus’s thyroid system is properly working, so maternal thyroid has to be available until birth before when the baby’s thyroid should begin to function  appropriately. If the thyroid role has a complication during development,  neurodevelopment problems may result, such as mental retardation. This could be prevented or likelihood reduced by administering postnatal thyroid hormones. There are other neurodevelopment problems, such as synapse development (the communication between two neurons to transmit a message), formation of myelin (a tissue that conducts a message faster), and migration of neurons that lead to the accurate locations  in the brain. These factors demonstrate how critical thyroid hormones are to the brain development . 

There are many signs and symptoms to hypothyroidism – here are a few some people experience such as feeling fatigue throughout day, mood swings, depression/anxiety, weight gain, hair loss, enlarged thyroid gland, and constipation. As for hyperthyroidism you can have rapid heartbeat, tremor of the hands, inability to concentrate, anxiety, increased appetite and not gain weight, increased perspiration, insomnia, prominent eyes that protrude from the socket (exophthalmos), edema (lower leg swelling), enlarged thyroid gland, and feeling fatigue throughout the day. Both conditions can lead to menstrual irregularities that could decrease a woman’s chances of being able to get pregnant. Unfortunately, these signs and symptoms can be overlooked, so the best way to know is to get a blood test to be able to diagnose this disease. A full thyroid panel is needed not only TSH, which is sometimes the only thing the doctors will check to know if you have abnormal levels of the thyroid hormones of T4 and T3.

Given how crucial the thyroid gland and thyroid hormones are to healthy functioning body thyroid issues should be treated immediately. If it is undiagnosed for too long, it can cause serious damage to organ systems of the body, such as bones, muscle, metabolism, and growth.