Trenbolone for Androgen Replacement Therapy The use of the anabolic steroid trenbolone has a long history in the bodybuilding but it has never really been considered a steroid suitable for therapeutic use in medicine. The U.S. Food and Drug Administration has not approved tren for use in humans. The media has often demonized it as a dangerous veterinarian steroid never intended for human use. However, the perception of trenbolone may soon change with the publication of a favorable study in a major scientific journal. Joshua Yarrow and his colleagues at the University of Florida feel that trenbolone may be a viable alternative to testosterone for androgen replacement therapy. They are set to publish their study results in the February 2011 issue of the American Journal of Physiology – Endocrinology and Metabolism. The researchers report that trenbolone enanthate may have certain advantages over testosterone that may make it an appealing treatment option for some individuals. Bodybuilders may be familiar with many of these findings. Trenbolone is not adversely affected by the aromatase or 5-alpha reductase enzymes that metabolize testosterone into estradiol and dihydrotestosterone, respectively. Bodybuilders have enjoyed tren for years precisely because they are able to avoid steroid side effects related to estrogen and DHT. Yarrow reports that low-dose trenbolone enanthate effectively produces anabolic effects in muscle size and partially maintains bone mineral density without causing prostate enlargement or polycythemia in castrated laboratory rats. Supraphysiological dosages of testosterone enanthate were required to produce anabolic effects similar to low-dose trenbolone administration. However, negative side effects of prostate enlargement and elevated hemoglobin became problematic at this dose of testosterone. Selective androgen receptor modulators (SARMs) may be the current darlings of scientific research into alternative options for androgen replacement therapy, but University of Florida researchers are excited by the “SARM-like potential” of trenbolone. They suggest that the actions of trenbolone are similar to selective androgen receptor modulators (SARMs). Low-dose trenbolone is called “SARM-like” because of the positive anabolic effects in muscle and bone without negative side androgenic side effects of prostate enlargement or polycythemia. Trenbolone may have benefits over testosterone in terms of androgen receptor activation, the upregulation of growth factors such as IGF-1 and fibroblast growth factor, and anticatabolic mechanisms. Competitive bodybuilders have often preferred using trenbolone in the weeks prior to a bodybuilding competition due to its purported effects at accelerating fat loss. The current study confirmed that trenbolone has more potent lipolytic effects on visceral adipose tissue than testosterone milligram per milligram. Furthermore, visceral fat loss increased in a dose-dependent manner with trenbolone. In other words, the more tren used, the greater the fat loss. Trenbolone’s lack of aromatization, while generally desirable, has often been problematic for bodybuilders who have used trenbolone as the only steroid in a cycle. Therefore, most bodybuilders include an aromatizable steroid such as testosterone or Dianabol in their trenbolone steroid stacks. Researchers also recognize that the lack of aromatization could be a potential problem if trenbolone is used alone in androgen replacement therapy. In their study, trenbolone only provided a partial bone protective effect when administered to castrated rats. The authors attribute this to the non-aromatizable nature of trenbolone. They conclude that low-dose trenbolone enanthate treatment has SARM-like effects on muscle/fat body composition. Androgen replacement therapy with low-dose trenbolone could potentially produce anabolic gains comparable to supraphysiological testosterone treatment without the associated side effects. The therapeutic risk-benefit profile of low-dose trenbolone appears superior to supraphysiological testosterone treatment; however, additional research into this treatment option is necessary. The researchers should be applauded for dispassionately and objectively researching the potential of trenbolone in androgen replacement therapy. Trenbolone is an anabolic steroid that has been demonized more than others due to its limited use (in pellet implants used by veterinarians to increase muscle growth in livestock). Fortunately, they looked past the political stigma associated with trenbolone to revisit a therapeutic use for an old steroid.