Thyroid Disease Symptoms and Signs. 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.hyroid Disease Symptoms and Signs. 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.