# Changes in uric acid metabolism and associated plasma proteomics during sex hormone therapy

## TL;DR

Sex hormone therapy affects uric acid levels and fat distribution, with changes linked to proteins related to fat metabolism.

## Contribution

The study identifies sex hormone therapy as a driver of uric acid and fat distribution changes, with proteomic insights into fat-related proteins.

## Key findings

- PUA decreases with feminizing therapy and increases with masculinizing therapy.
- Changes in uric acid clearance and fat distribution correlate with PUA changes.
- 126 PUA-associated proteins, including fat-related ones like adiponectin and leptin, are differentially expressed during therapy.

## Abstract

•Plasma uric acid (PUA) decreases with feminizing; increases with masculinizing therapy.•Uric acid clearance increases with feminizing; decreases with masculinizing therapy.•These changes are associated with changes in uric acid clearance and fat distribution.•Plasma proteomics show fat distribution-related proteins correlate with PUA changes.

Plasma uric acid (PUA) decreases with feminizing; increases with masculinizing therapy.

Uric acid clearance increases with feminizing; decreases with masculinizing therapy.

These changes are associated with changes in uric acid clearance and fat distribution.

Plasma proteomics show fat distribution-related proteins correlate with PUA changes.

Men generally have higher plasma uric acid (PUA) concentrations and are at greater risk for hyperuricemia-related diseases. Sex hormones may underlie this difference, though mechanisms remain unclear. Sex hormone therapy offers a unique opportunity to study these effects.

Participants were included from two prospective observational cohorts: ENIGI (n = 544, 12 months of feminizing [n = 260] or masculinizing [n = 284] hormone therapy) and KNIGHT (n = 28, 3 months of feminizing [n = 15] or masculinizing [n = 13] hormone therapy). Outcomes included changes in PUA (ENIGI), uric acid clearance (UAC; KNIGHT), fractional excretion of uric acid (FE-UA; KNIGHT), fat distribution (ENIGI), and PUA-associated plasma proteomics (KNIGHT).

PUA decreased during feminizing hormone therapy (−86  μmol/L [95% CI, −95; −77]) and increased during masculinizing hormone therapy (+61  μmol/L [95% CI, 53; 70]). During feminizing therapy, UAC increased (+1.1  mL/min [95% CI, 0.1; 2.1]) without changing FE-UA. During masculinizing therapy UAC and FE-UA decreased (UAC: −1.0  mL/min [95% CI, −1.7; −0.3]; FE-UA: −0.8% [95% CI, −1.3; −0.4]). Android-to-gynoid and visceral-to-subcutaneous fat ratios decreased with feminizing and increased with masculinizing therapy (p < 0.05) and correlated positively with PUA changes (p < 0.001). Proteomics identified 126 PUA-associated proteins differentially expressed during sex hormone therapy. While proteins directly involved in uric acid production were unchanged, proteins related to fat distribution (adiponectin, leptin, SHBG) associated with PUA changes.

PUA significantly changes during sex hormone therapy, most likely through changes in UAC and fat distribution. These findings emphasize the role of sex hormones in uric acid metabolism and provide insight into sex differences in hyperuricemia-related conditions.

Dutch Trial Register (ID: NL9517); ClinicalTrials.gov (ID: NCT04482920).