The thyroid gland as a small organ located in the lower front of the neck. There are layers of skin , fat, and muscle on top of it and it sits right on top of the windpipe, or trachea. It is shaped somewhat like a butterfly and actually goes backwards a little bit on both sides sort of wrapping around the windpipe a little, and it often touches the esophagus, the tube through which food goes to the stomach. This explains why sometimes even moderate enlargement of the thyroid can cause symptoms of difficulty in swallowing or breathing. The normal thyroid gland cannot be felt on physical examination because its consistency is very similar to all the soft tissues that surround it. Indeed, when a medical student or intern tells me “I felt her thyroid and it was normal”, I very dramatically stop whatever I’m doing and ask “Well, did you feel it, or is it normal, because you can’t have it both ways?” Probably the most common reason a thyroid gland can be felt on examination is either the presence of a nodule or tumor, or the presence of some underlying inflammation, often this can be some form of thyroiditis.

The thyroid gland has only one purpose, and that is to produce thyroid hormone. It does this by producing a protein called thyroglobulin and then attaching iodine to portions of it in order to produce the two forms of thyroid hormone called T3 and T4. T3 has three atoms of iodine attached to it and T4 has 4 atoms of iodine. There, so much for the mystery of why you are getting your T3 and T4 blood tests, they ARE thyroid hormone. These hormones have a profound effect on just about every part of your body. They affect your heart, your brain, intestines, skin, the list goes on and on. This is why excessive amounts of thyroid hormone or inadequate amounts of thyroid hormone can cause changes and symptoms in so many different parts of the body. Please don’t ask me to explain to you how these hormones do all of this because, frankly, I don’t know. This would take us down a path in microbiology, electronmicroscopy, cellular physiology, and other extremely specialized areas of science in which I am simply unqualified. The men and women who dedicate their lives to those pursuits are to be commended.

The good news about this is that if you must give up your thyroid gland because of tumor, cancer, or improper function, everything your gland used to do can be replaced with a small tablet of thyroid hormone. There are a number of choices as to what form your thyroid replacement will be, but no matter what form you choose, it is possible to completely replace what your body would be making if you still had your thyroid, and that is good news.