Current opinions invited review: testosterone and transgender medicine.

Objective: Transgender individuals have a gender identity incongruent with their sex assigned at birth. Social, medical and surgical methods are often affirming. This review focuses on updates from the last 18 months mainly in testosterone use in masculinising gender-affirming hormone therapy (GAHT) in postpubertal adults, and also antiandrogens for suppression or blockade of endogenous testosterone in feminising GAHT. Mental and sexual healthcare are vital for many transgender patients, but are not the focus of this review.

Results: There has been a considerable increase in publications regarding testosterone GAHT in recent years, though narrative reviews, opinion pieces and case series continue to dominate. There has also been a notable increase in prospective studies and valuable data particularly from large longitudinal cohorts and studies aiming to refine GAHT prescribing and better understand long-term effects on aspects such as fertility, cardiometabolic and bone health as well as adverse effects.

Conclusions: Testosterone GAHT is life changing. Increased research will help GAHT optimisation, and improve understanding of tissue-specific impacts and long-term safety. Longer-term data, prospective studies and utilisation of novel research tools and approaches are needed to enrich our understanding and prescribing of testosterone and its blockers in GAHT.