Thyroid: What Is Thyroxine?

The thyroid gland produces and releases important hormones that control body functions. The main hormone produced by the thyroid is called thyroxine.

Located at the base of the neck, the thyroid gland is the control center for metabolism. It uses iodine in the body to produce thyroxin or T4, said WiseGeek Health.

Thyroxine is crucial for proper functioning of the adrenal system, growth and normal development, optimal body weight control, mood, and energy.

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According to You and Your Hormones, the thyroid works on a feedback loop with a part of the brain called the hypothalamus and the pituitary gland. The hypothalamus releases a hormone that triggers the pituitary gland to release thyroid-stimulating hormone (TSH) which then prompts the thyroid gland to produce thyroxine and another hormone called triiodothyronine (T3).

Sometimes the thyroid gland can be overactive (hyperthyroidism) and produce too much thyroxine. Too much thyroxine results in a condition called thyrotoxicosis, said Hormone Health Network.

Thyrotoxicosis can also be caused by tumors on the thyroid gland or enlargement of the thyroid gland called goiter. This condition can cause irregularities in the menstrual cycle, irritability, weight loss, intolerance to heat, and an increase in bowel movement frequency.

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Another potential problem is the underproduction of thyroxine, or hypothyroidism. This condition is most often caused by autoimmune disease called Hashimoto’s thyroiditis, an iodine deficiency, or certain prescription medications, explained You and Your Hormones.

Hashimoto’s thyroiditis' symptoms are the opposite of those for hyperthyroidism and can include weight gain, fatigue, low heart rate, intolerance to cold temperatures, and low mood.

Hormone Health Network advises patients who suspect they have a thyroid disorder to discuss this with a physician.

Improper thyroxine levels can be determined through a series of simple blood tests. If a thyroid disorder is confirmed, physicians can develop the appropriate treatment plan.

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