Gender-affirming hormone therapy is the cornerstone of treatment for many transgender people, but its effects go far beyond the visible changes: they also reach internal organs such as the kidney. A new longitudinal study, published in Clinical Medicine Insights: Endocrinology and Diabetes, has closely tracked renal function in transgender people on hormone therapy and confirms that these changes exist, that they are gradual, and that they are not the same for everyone.
The researchers analysed a retrospective cohort of transgender individuals treated at Hospital Universitario San Ignacio in Bogotá, Colombia, all of them on gender-affirming hormone therapy. Their aim was to assess how the estimated glomerular filtration rate (eGFR) evolves over time — the indicator doctors use to evaluate kidney health.
The eGFR measures how much blood the kidneys filter per minute and is one of the most reliable figures for detecting kidney problems early. When it drops below certain thresholds, it points to a decline that needs monitoring. The question was whether the testosterone or oestrogens of affirming therapy modify that figure in a clinically relevant way.
The results show that there are indeed changes in renal function associated with hormone therapy, but that they occur slowly and depend on the type of treatment and on each individual. Rather than a sudden shock, what is observed is an evolution over time that should be measured periodically, highlighting the importance of continued medical follow-up for those receiving this therapy.
The finding does not mean that hormone therapy is dangerous for the kidney, but rather that, as with other organs, its impact should be monitored. The authors insist that clinical assessment of renal function should be part of the routine care of transgender people in treatment, just as lipids or blood pressure are monitored.
Studies like this one are essential because for years research on gender-affirming hormone therapy focused mainly on its cardiovascular and bone effects, leaving other organs in the background. Knowing these effects well makes it possible to adjust doses, anticipate problems, and offer safer, more personalised care.
The work is a reminder that transgender health care cannot be reduced to a single appointment: it requires a comprehensive, long-term view that accompanies each person across all the dimensions of their body and their life.
