Testosterone is the primary sex hormone and anabolic steroid in men. It is a widely used drug which is used by males as an anabolic–androgenic steroid but it is also the cornerstone in treatment of both hypogonadal men and transgender people. This letter will focus on the use of testosterone as therapy for hypogonadal and transgender men. However clinicians may also encounter males who use testosterone as an anabolic–androgenic steroid. In this group we recommend to strongly advice discontinuation of use; and if hematocrit levels exceed >0.55 perform a phlebotomy.
