The thyroid gland is located in the neck and produces thyroid hormones that regulate energy use in the body. It is a single gland with right and left sides joined in the middle by a narrow isthmus.
Disorders of the thyroid are mainly either hormone production problems (too much or too little hormone) or problems of enlargement of the gland. Enlargements, or goitres, can be diffuse or multinodular. Nodules may be benign (not cancer) or malignant (cancer). Significant enlargements may cause pressure symptoms such as difficulty with breathing or swallowing, especially if the thyroid extends below the collar bones.