Tetrahydrogestrinone (THG) - Commonly known as The Clear, Tetrahydrogestrinone (THG is a type of steroid that had only been recently placed into scheduling as of 2005 and is noted unapproved by FDA. It basically binds with the androgen receptor instead of estrogen which makes it effective in increasing endurance for athletes. According to history, this was the secret of winning for the gold medalist Marion Jones, a sprinter athlete. However, longer association with this type of steroid can lead to infertility in both male and female. Using the steroids abuse test kit, a person may be held liable for a positive THG steroid test.
Stephan Bonnar and Josh Barnett , mixed martial arts (MMA) fighters from the UFC and PRIDE Fighting Championships , have also tested positive for the banned substance.  After the World Extreme Cagefighting show on January 20, 2006 Muay Thai turned MMA fighter Kit Cope also tested positive for boldenone.  Following the Strikeforce card on June 22, 2007 former PRIDE and UFC fighter Phil Baroni tested positive for boldenone, as well as stanozolol .  At a K-1 WGP event in Las Vegas on August 17, 2007 two fighters, Rickard Nordstrand and Zabit Samedov , both tested positive for boldenone.  Alexandre Franca Nogueira tested positive for boldenone in July 2008.