Liothyronine is used to treat underactive thyroid (hypothyroidism). It replaces a hormone that is normally produced by the thyroid gland. Low thyroid levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. It is important to have adequate levels of thyroid hormone in your bloodstream to maintain normal mental and physical activity.
Cytomel is not a steroid, but more a of a cutting aid. It's a synthetic form of the thyroid hormone tri-iodio-thyronine or T3, made up of a metabolite of the amino acid tyrosine and 3 iodine ions. In the body it in turn is made from another hormone, T4, which is secreted by the thyroid under influence of the pituitary hormone TSH (Thyroid stimulating hormone). If a shortage of either TSH or T4 is noted, usually doctors may opt for a replacement therapy. These days the most common prescription is synthetic T4 (synthroid), but in more severe cases of permanent thyroid dysfunction, the choice is given to Cytomel. Simply because T4 is mostly active through its conversion to T3 and T3 is 4-5 times stronger than T4 on a mcg for mcg basis. Cytomel may also be used for purposes other than those listed in this medication guide. Please consult your physician before taking any medication.