Trenbolone is essentially a derivative of Nandrolone with some very significant differences in its chemical properties and strength. Trenbolone and its parent hormone Nandrolone both belong to a class/category of anabolic steroids known as 19-nor compounds, or 19-nors (short for 19-nortestosterone). 19-nor anabolic steroids are labeled as such because they lack the 19th carbon on their structure – this carbon exists on Testosterone and all other anabolic steroids with the exception of 19-nor compounds, such as Nandrolone and Trenbolone.
Genitourinary effect following chronic administration and/or large dosages of anabolic steroids can result in oligospermia and decreased ejaculatory volume. Elderly male patients may experience prostatic enlargement resulting in urinary obstruction. Priapism and excessive stimulation may develop.
In female patients the use of anabolic steroids may result in virilization including deepening voice, hirsutism, acne, clitomegaly (not reversible), and menstrual abnormalities. Discontinuation of medication at signs of mild virilization may prevent irreversible virilization.
Alterations in libido may occur (increased/decreased). [ Ref ]