Relationship Between Adherent Perinephric Fat and Sex Hormone Levels in Serum and Fat in Patients Undergoing Robotic-Assisted Partial Nephrectomy: A Prospective Study

Background: Perinephric fat removal is essential for safe and effective robotic-assisted partial nephrectomy (RAPN). Adherent perinephric fat (APF) occasionally compromises RAPN, but the relationship between such fat and sex hormone levels is unclear. We explored a possible association between APF and sex hormone levels in serum and APF tissue. Patients and Methods: We conducted a prospective study from 2021 to 2022 at Gunma University Hospital. Fifty patients treated using RAPN were analyzed. We measured the testosterone (T) and estradiol (E) levels in serum and perinephric fat using liquid chromatography-mass spectrometry (LC-MS/MS). The correlations between the extent of adherence measured intraoperatively and hormone concentrations were examined. Results: Of the 50 cases, 36 were male, and 14 were female. APF was observed in 16 of the male patients but in no female patients. In male patients, the T levels in perinephric fat were significantly higher in patients with APF. E2 levels in perinephric fat tissue were also significantly higher in patients with APF. Conclusion: In the 36 male patients lacking APF, there were no significant differences in the serum levels of T compared with those with APF, but a significant difference was apparent in APF tissue. The changed T level in APF tissue may have affected APF development.