Cross-Sex Testosterone Therapy Modifies the Renal Morphology and Function in Female Rats and Might Underlie Increased Systolic Pressure.

Testosterone esters are hormones commonly used for affirming gender identity in transmen. The present study evaluates the effect of testosterone on renal morphology and function in an animal model submitted to cross-sex hormone therapy used for transmen. Two-month-old Wistar rats were divided into three groups: male control (MC), female control (FC), and female on testosterone therapy (FTT). The FTT-group received testosterone cypionate (3.0 mg/kg, i.m.), and the MC and MF groups received vehicle oil every 10 days for 4 months. Renal function and indirect systolic blood pressure (SBP) measurements were evaluated at 6 months of age. Plasma and urine concentrations of urea, creatinine, sodium, potassium, osmolality, and glomerular filtration rate (GFR) were measured. The kidneys were weighed, paraffin-embedded, and histological sections were prepared to evaluate the glomerular area. We verified that FTT-group, in comparison to FC, had increased kidney weight [MC: 3.2±0.05; FC: 1.8±0.04; FTT: 2.2±0.06; g], ], decreased urine osmolarity [MC: 486.9±18.3; FC: 1012.0±5.4; FTT: 768.2±40.3 mOsm/L/g kw], reduced GFR [MC: 0.77±0.04; FC: 0.78±0.02; FTT: 0.67±0.03; mL/min/g kw], larger glomerular area [MC: 9,334±120.8; FC: 7,884±112.8; FTT: 9,078±133.4 µm2 ], and higher SBP [MC: 126±3.4; FC: 119±1.0; FTT: 131±1.4; mmHg]. Sodium excretion was higher in FC and FTT in comparison to MC [MC: 0.34±0.05; FC: 0.56±0.06; FTT: 0.54±0.04; mEq/24h/g kw]. Cross-sex hormone therapy with testosterone in female rats induces renal morphofunctional changes and may underlie increased systolic pressure, suggesting an adaptation similar to what is observed in transmen on long-term testosterone therapy.