Introduction:
Glutathione reductase (GR) is a key enzyme that catalyzes the reduction of oxidized glutathione to its reduced form, playing a vital role in protecting cells from oxidative damage caused by the accumulation of reactive oxygen species. This study employed the ultraviolet enzymatic method to measure serum GR activity, aiming to investigate its distribution among apparently healthy adults and preliminarily establish reference intervals for serum GR.

Material and methods:
A total of 6,180 apparently healthy individuals participated in this study. Serum GR activity was measured using the AU5800 fully automated biochemical analyzer and its corresponding commercial kit. The Kolmogorov-Smirnov test was used to analyze the distribution of serum GR activity. Following the guidelines of C28-A3 and WS/T 402-2024, the reference interval for serum GR was determined using the bilateral percentile method, covering the range from the 2.5th to the 97.5th percentile.

Results:
Serum GR activity in this study exhibited a non-normal distribution. Significant gender-based differences in GR activity were observed, while no significant variations were found across different age groups. Based on these findings, gender-specific reference intervals for serum GR were established: 26.6–51.8 U/l for males and 29.7–55.3 U/l for females.

Conclusions:
This study is the first to establish gender-specific reference intervals for serum GR in apparently healthy adults. These intervals provide essential guidance for health screening and improve the diagnosis and management of related clinical conditions.