Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn't produce enough of certain important hormones. Women are more likely to have hypothyroidism as it upsets the normal balance of chemical reactions in your body. Thyroid disorders are common affecting about 12 percent of Americans at some point during their lives.
According to healthline.com, the thyroid is a small, butterfly-shaped gland that drapes across the front of your windpipe. For an idea on location, you will feel your thyroid by placing two fingers on the side of your windpipe. After swallowing, the gland slides under your fingers.
The gland releases a thyroid hormone, which controls the growth and metabolism of essentially every part of your body. The pituitary gland in the middle of your head monitors your physiology and releases thyroid-stimulating hormone (TSH). TSH is the signal to the thyroid gland to release thyroid hormone (1).
“Sometimes TSH levels increase, but the thyroid gland can't release more thyroid hormone in response. This is known as primary hypothyroidism, as the problem begins at the level of the thyroid gland. Other times, TSH levels decrease, and the thyroid never receives the signal to increase thyroid hormone levels. This is called secondary hypothyroidism.”
Though there is not one direct symptom of hypothyroidism, outside weight gain or fatigue patients may experience: