The Effect of Gender-Affirming Hormone Treatment on Kidney Function Trajectories in Transgender and Gender-Diverse...

Administration of testosterone was associated with decline in the slope of eGFR in transgender veterans. Administration of testosterone was associated with increase in creatinine in first 12 months of hormone initiation in transgender veterans. Administration of estrogen was associated with stability of eGFR slope in transgender veterans.

The impact of hormone therapy (HT) on kidney function in transgender and gender-diverse (TGD) individuals remains poorly understood, and this lack of data poses challenges in caring for TGD individuals with kidney disease. The aim of this study was to compare serum creatinine levels and eGFR slope, a critical marker of kidney function, in transgender women (TW) and transgender men (TM) relative to cisgender (non-TGD) controls.

We conducted a longitudinal cohort study of veterans using Veterans Health Administration care from January 2006 to December 2019. Serum creatinine and eGFR were assessed using algorithms based on affirmed gender and sex assigned at birth. Within-group changes over time were assessed using generalized linear mixed-effect models with random intercept and time modeled as a categorical variable. Two-way fixed-effects models were used to assess changes in eGFR slopes relative to HT initiation compared with cisgender controls.

The analytic dataset included 6616 veterans of whom 262 were receiving HT (214 [3%] TW and 48 [0.72%] TM) and 6354 were cisgender not receiving HT (1988 [30%] cisgender women and 4366 [66%] cisgender men). Serum creatinine was higher as early as 3 months after HT initiation in TM veterans with stabilization by 12 months, whereas TW veterans did not demonstrate any significant change in their serum creatinine. eGFR was significantly lower in TM veterans after HT initiation, whereas it remained stable in TW veterans.

Our findings suggest that HT is associated with divergent effects on kidney function. These findings suggest the need for individualized kidney monitoring and potentially refined eGFR calculations for TGD populations.