What is the function of thyroid hormones?

Thyroid hormones set metabolic activity and are thus responsible for the speed at which every enzyme action in the body takes place. Thyroid hormone balance in the brain is crucial for maintaining physical and mental health. They have a direct effect on the majority of organs found in our body. These hormones regulate how many calories you burn, how warm you feel, and even how fast our heart beats. Thyroid imbalance not only affects your weight, but also your mood, emotions, behavior, sex life, menstrual problems in women, infertility, depression and anxiety disorders. In short, their function is to regulate our body’s metabolism. Symptoms of thyroid imbalance can mimic other hormonal imbalances; therefore as many as 13 million Americans may be undiagnosed and/or misdiagnosed.

What happens when I have too much or too little thyroid hormones?

More than 10 million Americans have been diagnosed with thyroid disease, and another 13 million people are estimated to have undiagnosed thyroid problems in the U.S. alone. A February, 2000 research study found that the estimated number of people with undiagnosed thyroid disease may be 10% - a level that is double what was previously thought. Women are at the greatest risk, developing thyroid problems seven times more often than men.
Hyperthyroidism is defined as a condition in which there is an overproduction of thyroid hormone from the thyroid gland. Hypothyroidism is the opposite, where there is an underproduction of thyroid hormone from the thyroid gland. Hypothyroidism is a very common condition. It is estimated that 3 to 5% of the population has some form of hypothyroidism. The condition is more common in women than in men, and its incidence increases with age. In fact, hypothyroidism is most common in women during the peri-menopausal and postmenopausal years; it is estimated that approximately 26% of women in or near menopause are diagnosed with hypothyroidism.

Here are some signs and symptoms of hyperthyroidism and hypothyroidism:

Where do thyroid hormones come from?

Thyroid hormones are made and released from the thyroid gland located in the front base of the neck. The thyroid typically secretes thyroid hormones in response to thyroid stimulating hormone (TSH) produced by the pituitary gland. Special cells in the pituitary gland determine the normal range of thyroid hormone in the body, which is the set point. As blood flows through the pituitary these cells measure the hormone levels and can tell whether or not it is at the set point. Under normal conditions, the pituitary gland sends out enough TSH to tell the thyroid to maintain a balanced level of thyroid hormones. If the levels are low, the pituitary sends out more TSH to tell the thyroid to make more hormones. Similarly, if the levels are elevated, the pituitary is inhibited from sending out TSH and levels of thyroid hormone will fall.