Transgender men initiating testosterone therapy via subcutaneous abdominal injections did not experience any change in free and total serum testosterone levels when compared with levels measured during previous intramuscular testosterone injections, study data show.

“Recent reports indicate that [subcutaneous] administration of testosterone esters may be an acceptable alternative to [intramuscular] injections in hypogonadal men and [female-to-male] transgender patients,” Julie McFarland, MD, of the department of obstetrics and gynecology at Maine Medical Center in Portland, and colleagues wrote. “Genetic females undergoing gender transition provide an ideal opportunity to assess pharmacokinetics because their low endogenous secretion of testosterone contributes minimally to serum measurements of testosterone. Providing information regarding the pharmacokinetics of testosterone ester injections will further characterize its efficacy and reliability as well as provide information regarding appropriate timing of serum sampling to monitor therapy.”