to keep your ... Within the lay population and in some medical communities, there is a perception that adding synthetic triiodothyronine, or liothyronine, to levothyroxine ... Levothyroxine is a replacement for a hormone that is normally produced by your thyroid gland to regulate the body's energy and metabolism. ... Levothyroxine Effects, Dosage, and Side Effects Information. " Background The treatment of hypothyroidism with levothyroxine is effective and simple; however, recommendations