# Urinary marker of oxidative stress in children correlates with molecules in exhaled breath

## TL;DR

This study shows that breath analysis can detect oxidative stress in children, linking breath molecules to a known urinary marker.

## Contribution

The study identifies breath features correlated with a urinary oxidative stress biomarker in children.

## Key findings

- 71 breath features significantly correlated with urinary 8-iso-PGF2α levels.
- Breath-predicted and actual urinary 8-iso-PGF2α levels showed moderate agreement.
- Real-time breath analysis shows promise for assessing oxidative stress non-invasively.

## Abstract

Real-time breath analysis has shown potential as a non-invasive method for detecting oxidative stress and airway inflammation. However, there is a lack of data on the association of full-breath profiles with established urinary biomarkers of oxidative stress and respiratory inflammation, which could help advance the implementation of this method in clinical practice. We analyzed breath profiles of 25 tobacco smoke-exposed and 103 non-exposed children via real-time secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS) and determined in parallel the urinary concentrations of biomarkers of oxidative stress and respiratory inflammation. We evaluated the correlation between breath features and urinary biomarkers and tested the prediction of these biomarkers by exhaled breath. We found 71 breath features that correlated significantly with the urinary oxidative stress marker 8-iso-prostaglandin F2α (8-iso-PGF2α). The agreement (mean ± standard deviation) (Lin’s concordance correlation) between breath-predicted and actual urinary 8-iso-PGF2α levels was 0.37 (0.05). In conclusion, our results suggest that the real-time breath analysis via SESI-HRMS has promising potential to gauge oxidative stress.