Breath Analysis: Identification Of Potential Volatile Biomarkers For Non-invasive Diagnosis Of Chronic Kidney Disease (Ckd)

Authors: Alessia Di Gilio1,2*, Jolanda Palmisani1,2*, Marirosa Nisi1,2, Valentina Pizzillo1,2, Marco Fiorentino3, Stefania Rotella3, Nicola Mastrofilippo3, Loreto Gesualdo3, Gianluigi de Gennaro1,2

Affiliations: 1 Department of Bioscience, Biotechnologies and Environment - University of Bari, 70126 Bari, Italy; 2 Apulian Breath Analysis Center (CeRBA), IRCCS Giovanni Paolo II, 70124 Bari, Italy 3 Nephrology, Dialysis and Transplantation Unit, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRE-J), University of Bari Aldo Moro, 70121 Bari, Italy

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Abstract:

Introduction: Recently, volatile organic compounds (VOCs) determination in exhaled breath has been growing interest due to its promising potential in early diagnosis of several pathological conditions including chronic kidney disease (CKD) [1]. Moreover, considering its non-invasive and cost-effective feature, breath analysis could represent a promising tool to enhance the care of chronic kidney patients because it could provide valuable diagnostic insights and identify patients at risk of complications, avoiding the continued recourse to blood draws. Therefore, this study aimed to identify the breath VOCs pattern providing an accurate, reproducible, and fast CKD diagnosis also at early stages of the disease.

Methods: A cross-sectional observational study was carried out, enrolling a total of 30 subjects matched for age and gender. More specifically, the breath samples were collected from: a) n. 10 patients with end-stage kidney disease (ESKD) on chronic hemodialysis before undergoing hemodialysis treatment (DIAL); b) n.10 patients with mild-moderate CKD (G) including 3 patients in stage G2 with mild albuminuria, and 7 patients in stage G3 [2] and c) 10 healthy controls (CTRL). For each volunteer, an end-tidal exhaled breath sample and an ambient air sample (AA) were collected at the same time on two sorbent tube by an automated sampling system (Mistral – Predict srl) and analyzed by Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC/MS -TD Markes Unity 2 - GC Agilent 7890/MS Agilent 5975) [3].

Results: A total of 110 VOCs were detected in breath samples but only 42 showed levels significatively different respect to AA. Nonparametric test as Wilcoxon/Kruskal Wallis tests (R version 3.5.1) allowed to identify the most weighting variables able to discriminate between AA, DIAL, G and CTRL breath samples. A promising multivariate data mining approach incorporating only selected variables (showing p-values lower than 0.05) such as nonanal, pentane, acetophenone, pentanone, undecane, butanedione, ethyl hexanol and benzene, was developed and cross-validated providing a prediction accuracy equal to 87% and to 100% in identifying patients with both mild-moderate CKD (G) and ESKD (DIAL) patients, respectively.

Conclusions: Although the number of collected data was limited and the developed method requires further validation on a greater population of data, the results of this study are very interesting and promising. The advancement of a non-invasive breath test enabling the early identification of toxin accumulation in CKD patients could result in less severe damage and simpler treatment options for the patients also reducing healthcare costs.

References: [1] Manoj Khokhar 2024. J. Breath Res. 18 024001 [2] Summary of Recommendation Statements. Kidney Int Suppl (2011);3(1):5-14. [3] Di Gilio et al., Molecules 2020, 25 (24): 5823