The thyroid gland is a powerhouse for your body that helps you have healthy weight, good energy, healthy hormones, a strong heart, and much more. The thyroid is a small butterfly shaped gland that only weighs a ounce. It sits in the lower neck and wraps around the trachea. It has two lobes connected by an isthmus. If you put your finger on your Adam's apple (thyroid cartilage), the thyroid is right below that.
Now the throid secretes its' hormones directly into the bloodstream where they are transported to every tissue in the body. These hormones control how fast the cells in your body synthesize proteins and consume oxygen. This is what drives your metabolism and this process directly effects the growth and repair of every cell in your body. The two primary hormones the thyroid secretes are called T3 and T4. About 80% of the hormones are T4 and 20% T3. T3 is far more potent of the two and has 5-10X the strength of T4. A healthy thyroid only produces a teaspoon of these hormones in a year. A little goes a long way.
Experts say that 59 million people in America suffer from thyroid disease and about half of these are undiagnosed. Why such a large number and why are so many undiagnosed? I will go into more details in the disease specific sections to help answer that question. However, it is important to note the conventional thyroid testing is very inadequate and does not reveal the underlying causes that lead to thyroid disease. Many times a person is told that there is nothing wrong with her/his thyroid when they are experiencing classic Hypothyroid (low thyroid) symptoms like fatigue, easy weight gain, depression, thinning hair or dry skin. Conventional testing is not sensitive enough to detect changes in thyroid function that can produce some very uncomfortable symptoms.
Calcitonin is another hormone produced by the thyroid gland. It acts to reduce blood calcium levels opposing the effects of parathyroid hormones. Calcitonin is very important in building strong bones as it stimulates the movement of calcium out of the blood and into the bones. Long term use of synthetic thyroid hormones can lead to osteoporosis. This happens because a synthetic thyroid hormone cannot duplicate the activity of a healthy thyroid.
The thyroid gland is controlled by the hypothalamus and pituitary glands. When levels of T4 and T3 are too low in the bloodstream the hypothalamus gland in the brain detects that and releases TRH (Thyrotropin-Releasing Hormone) which stimulates the pituitary gland to release TSH (Thyroid Stimulating Hormone) which tells the thyroid to release more T4 and T3. There is also negative feedback loop between these glands so as thyroid hormone blood levels rise to a needed level the hormone releasing process will be shut down. Obviously, it's important to have a healthy functioning hypothalamus and pituitary to have a happy thyroid.