Hyperthyroidism 101: What Happens When Your Thyroid Stops Functioning Properly?

Medically Reviewed by Dr. Samantha Miller

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Once a little known part of the body, the thyroid has gained much attention in recent years, mainly because it plays such an important role in how well the body's metabolism works. When the thyroid isn't functioning properly, it can lead to numerous problems, including hyperthyroidism. 

What Is the Thyroid?

The thyroid is a small, butterfly-shaped gland located in the neck, in front of the windpipe. It is responsible for producing the hormones triiodothyronine (T3) and thyroxine (T4). The T3 and T4 hormones control the body’s metabolism — how every cell in the body uses energy. 

Hyperthyroidism, also known as an overactive thyroid, is what happens when the thyroid produces too much of these thyroid hormones. Slightly more than 1% of Americans are affected by hyperthyroidism. Although hyperthyroidism can affect people of all genders, it's about 10 times more common in women than men, and usually appears between the ages of 20 and 40 years.