The effects of gender-affirming hormone therapy on myocardial, hepatic, pancreatic lipid content, body fat distribution and other cardiometabolic risk factors: A magnetic resonance-based study in transgender individuals.

Purpose: We aimed to assess the changes in body fat distribution, intraorgan lipid accumulation, and cardiometabolic risk factors after 6 months of gender-affirming hormone therapy (GAHT) in transgender men (TM) and transgender women (TW).

Methods: Conducted at the Medical University of Vienna between 2019 and 2022, the study included 15 TW and 20 TM. We conducted magnetic resonance imaging and spectroscopy to determine the visceral (VAT) and subcutaneous adipose tissue (SAT) amounts, the VAT/SAT ratio, and the intraorgan lipid content (liver, pancreas, myocardium), bloodwork, and an oral glucose tolerance test at baseline and after 6 months of GAHT.

Results: Pancreatic, hepatic, and intramyocardial lipid contents did not significantly change in either group after 6 months of GAHT. In TW, VAT/SAT ratio decreased significantly from baseline 0,930 (IQR 0,649-1,287) to 0,758 (IQR 0,424-0,900; p = 0,011) after 6 months of GAHT. The updated homeostatic model assessment for insulin sensitivity (HOMA2-%S) significantly decreased from 83,03 % (±31,11) to 64,27 % (±18,01; p = 0,047), indicating decreased insulin sensitivity, while the updated homeostatic model assessment for β-cell function (HOMA2-%β) increased (from 128,11 % (±35,80) to 156,80 % (±39,49); p = 0,020) in TW after 6 months of GAHT. In TM, there were no changes in glucose metabolism parameters except for an increase in HbA (5,1% (±0,3) vs 5,3% (±0,4), p = 0,001).

Conclusions: 6 months of GAHT were not associated with statistically significant changes in myocardial, hepatic, or pancreatic lipid content. Short-term GAHT led to a marked body fat redistribution with a significant decrease in the VAT/SAT ratio in TW.