The thyroid, a small butterfly-shaped gland in the neck, is responsible for producing hormones that regulate the metabolism. The thyroid is only one part, however, in a "delicate feedback mechanism," according to the EndocrineWeb website. The thyroid is controlled by the pituitary gland, which is itself controlled by the hypothalamus, a part of the brain. If your thyroid does not naturally produce sufficient levels of the hormones required to keep your body healthy, your doctor can prescribe medication containing synthetic thyroid hormone. If instead your thyroid causes overactivity of your metabolism, you will require treatment to decrease the level of thyroid hormones in your blood.
The Thyroid's Role
Your thyroid gland is the only organ in your body capable of absorbing iodine, a naturally occurring element in water and many foods. The thyroid combines iodine with the amino acid tyrosine, converting it into two thyroid hormones--T4, or thyroxine, and T3, or triiodothyronine--which are then released into the bloodstream. The thyroid hormones regulate the metabolism of every cell in your body, and are crucial to human growth as well as the reproductive, digestive, cardiovascular and nervous systems.
Pituitary Gland
The pituitary gland, which lies at the base of the brain, controls the thyroid gland by producing TSH, or thyroid stimulating hormone. If the level of thyroid hormones in your system drop too low, the pituitary gland responds by producing TSH, which then prompts the thyroid to manufacture more T3 and T4. The opposite is also true--if thyroid hormone levels are high, the pituitary gland shuts off production of TSH.
Hypothalamus
The third part of the thyroid hormone feedback system is the hypothalamus gland, the part of the brain responsible for critical metabolic processes such as sleep, hunger, thirst and body temperature. The hypothalamus produces TRH, or TSH releasing hormone, which prompts the pituitary gland in its monitoring of the thyroid gland.
Role of Medication
Certain conditions can cause your thyroid to become either under- or overactive. The signs of an underactive thyroid, or hypothyroidism, include fatigue, constipation, sensitivity to cold, elevated blood cholesterol, heavy menstrual periods, dry skin and depression. If your thyroid cannot produce enough natural thyroid hormone, your doctor will prescribe synthetic thyroxine in pill form. Symptoms of an overactive thyroid, or hyperthyroidism, include rapid weight loss, heart palpitations, nervousness, insomnia, increased perspiration and hair loss. Depending on the cause of the metabolic increase, doctors may treat hyperthyroid patients with anti-thyroid drugs, radioactive iodine or thyroid surgery.
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