L-Thyroxine is a synthetically manufactured thyroid hormone. Its effect is similar to that of natural L-thyroxine (L-T4) in the thyroid gland. L-thyroxine is one of two hormones which is produced in the thyroid. The other one is L-trliodthyronine (L-T3, see Cytomel). Lthyroxine is clearly the weaker of the two hormones. For this reason it is often used for a longer time period than L-T3. Bodybuilders use L-Thyroxine to accelerate the metabolizing of carbohydrates, proteins, and fat. The body burns more calories than usual so that a lower fat content can be achieved or the athlete burns fat although he takes in more calories. In the past L-Thyroxine was often used by competing bodybuilders. Unfortunately, with increased dosages (more than 400 to 600 mcg/day) usually not only more fat but more carbohydrates and proteins are burned as well. The athlete no doubt becomes harder but he can also lose muscle mass if steroids are not administered simultaneous. L-Thyroxine is rarely used today since most athletes use Cytomel or Triacana. When used properly there are few side effects to L-Thyroxine.
Dosages that are too high and, in particular; dosages that are increased too quickly and too early at the beginning of intake can cause trembling of the fingers, excessive perspiration, diarrhea, insomnia, nausea, increased heartbeat, inner unrest, and weight loss. The dosages taken by athletes are usually in the range of 200-40q mcg/day. We advise that you begin with a small dose and increase it slowly and evenly over several days. L-Thyroxine is a prescription drug and available only in pharmacies. One hundred tablets of 150 mcg each of the compound Levothroid cost about $50 on the black market. One hundred tablets of 200 mcg each of Synthroid by the Boots Company usually cost about the same. Unlike Cytomel and Triacana, L-Thyroxine is rarely found on the black market.