Endocrine Abstracts

JOINT1725

Background: An increasing number of individuals worldwide identify as transgender, and many undergo gender-affirming hormone therapy (GAHT) to align their physical characteristics with their gender identity. Feminizing GAHT typically involves estradiol, with or without an antiandrogen, while masculinizing GAHT involves testosterone. Simultaneously, the worldwide prevalence of chronic kidney disease (CKD) rises, presenting a significant global health challenge. Men in the general population have a higher risk of advanced CKD than women, potentially due to differences in sex hormone concentrations. Previous studies in transgender individuals confirmed this role for sex hormones, as estimated glomerular filtration rate (eGFR) increases with feminizing GAHT and decreases with masculinizing GAHT. However, these studies were limited to short-term follow-up, leaving long-term effects of GAHT on CKD risk unclear. This current study aimed to fill these knowledge gaps, by investigating the long-term risk of advanced CKD in transgender individuals undergoing GAHT, compared with the general population.

Methods: This retrospective cohort study included individuals who visited the gender identity clinic at Amsterdam University Medical Centre (1972–2018). Their records were linked to a nationwide registry (2012–2022). Advanced CKD was defined as eGFR <30 mL/min per 1.73m² or chronic dialysis. Individuals who did not use GAHT or died before 2012 were excluded. Standardized incidence ratios (SIRs) were calculated for transgender women and -men using general population incidence rates stratified by age and socioeconomic status (based on education, income and employment).

Results: The study included 2,694 transgender women (follow-up: 22,759 person-years) and 1,612 transgender men (follow up: 12,970 person-years). Median age at GAHT initiation was 30 years (IQR 24–41) for transgender women and 24 years (IQR 20–32) for transgender men. Seventeen transgender women developed advanced CKD, with no increased risk compared with men (SIR 1.6; 95% CI, 0.9–2.5), but a significantly higher risk compared with women (SIR 2.5; 95% CI, 1.4–3.9) in the general population. Eight transgender men developed advanced CKD, with significantly higher risks compared with both women (SIR 3.8; 95% CI, 1.5–7.0) and men (SIR 2.6; 95% CI, 1.0–4.9) in the general population.

Conclusion: Transgender women undergoing feminizing GAHT are at higher risk of advanced CKD compared with women, but not with men in the general population. Transgender men undergoing masculinizing GAHT are at higher risk compared with both women and men. These findings underline the need for tailored clinical care to address the unique health risks faced by transgender individuals.