Liothyronine sodium is a synthetically manufactured prescription thyroid hormone. It specially consist of the the L-isomer of the natural thyroid hormone triiodothyronine (T3). Thyroid hormone stiumlate basal metabolic rate, and are involved with many cellular functions including protein, fat, and carbohydrate metabolism. Liothyronine sodium is used medically to treat hypothyroidism, a condition where the thyroid gland does not produce sufficient levels of thyroid hormone. Hypothyroidism is usually diagnosed with a serum hormone profile, and may manifest itself with symptoms including loss of energy, lethargy, weight gain, hair loss, and changes in skin texture. The first medication that included T3 was technically a thyroid extract, first given to a patient with my edema in 1891. Natural thyroid extracts contained therapeutically viable levels of the thyroid hormones T3 and T4, and were widely used in medical practice for more than 60 years. In the 1950s, however, these drugs slowly start giving way to new synthetic thyroid medications, namely liothyronine sodium and levothyroxine sodium, which were consistent in dosage and effect, and more desirable to consumers than prepared animal extracts. Although liothyronine sodium and levothyroxine sodium are both widely available in the U.S. and abroad to this day, liothyronine retains a significantly smaller portion of the global thyroid market. Given its more potent and fast acting effect, however, liothyronine sodium remains a popular thyroid drug with bodybuilders and athletes. Liothyronine sodium is most commonly supplied in oral tablets of 5mcg, 25mcg, and 50mcg.