Underactive Thyroid Anatomy
To better understand hypothyroidism, it helps to understand the anatomy of the thyroid gland.
The thyroid is a butterfly-shaped organ located in the neck, next to the Adam's apple.
The thyroid gland is responsible for regulating the body's metabolic rate. This is accomplished through the production and release of thyroid hormone into the bloodstream. Thyroid hormones are normally present in the bloodstream in tiny quantities. Too much thyroid hormone in the bloodstream is called hyperthyroidism. When there is too little, the condition is referred to as hypothyroidism.
- Escobar-Morreale HF, Botella-Carretero JI, Escobar del Rey F, Morreale de Escobar G. REVIEW: Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine. J Clin Endocrinol Metab. 2005 Aug;90(8):4946-54. 
- Rovet J, Daneman D. Congenital hypothyroidism: a review of current diagnostic and treatment practices in relation to neuropsychologic outcome. Paediatr Drugs. 2003;5(3):141-9. 
- Simon NM, Blacker D, Korbly NB, Sharma SG, Worthington JJ, Otto MW, Pollack MH. Hypothyroidism and hyperthyroidism in anxiety disorders revisited: new data and literature review. J Affect Disord. 2002 May;69(1-3):209-17.