Thyroid disease is a common problem that can cause symptoms because of over- or under-function of the thyroid gland. The thyroid gland is an essential organ for producing thyroid hormones, which maintain are body metabolism. The thyroid gland is located in the front of the neck below the Adam's apple. Thyroid disease can also sometimes lead to enlargement of the thyroid gland in the neck, which can cause symptoms that are directly related to the increase in size of the organ (such as difficulty swallowing and discomfort in front of the neck).