First observation of a potential non-invasive breath gas biomarker for kidney function

Abstract

We report on the search for low molecular weight molecules-possibly accumulated in the bloodstream and body-in the exhaled breath of uremic patients with kidney malfunction. We performed non-invasive analysis of the breath gas of 96 patients shortly before and several times after kidney transplantation using proton-transfer-reaction mass spectrometry (PTR-MS), a very sensitive technique for detecting trace amounts of volatile organic compounds. A total of 642 individual breath analyses which included at least 41 different chemical components were carried out. Correlation analysis revealed one particular breath component with a molecular mass of 114 u (unified atomic mass units) that clearly correlated with blood serum creatinine, which is the currently accepted marker for assessing the function of the kidney. In particular, daily urine production showed good correlation with the identified breath marker. An independent set of seven samples taken from three patients at the onset of dialysis and three controls with normal kidney function confirmed a significant difference in concentration between patients and controls for a compound with a molecular mass of 114.1035 u using high mass resolving proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). A chemical composition of C7H14O was derived for the respective component. Fragmentation experiments on the same samples using proton-transfer-reaction triple-quadrupole tandem mass spectrometry (PTR-QqQ-MS) suggested that this breath marker is a C7-ketone or a branched C7-aldehyde. Non-invasive real-time monitoring of the kidney function via this breath marker could be a possible future procedure in the clinical setting.

The Measurement of Ammonia in Human Breath and its Potential in Clinical Diagnostics

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FEV manoeuvre induced changes in breath VOC compositions: an unconventional view on lung function tests

“…It holds promise towards noninvasive clinical diagnosis as well as therapeutic and physiological monitoring12345678910. In early years, researchers were mainly focused on the discovery of trace (~ppbV to ~pptV ranges) gases in human breath as unique biomarkers for diseases.…”

Monitoring of Selected Skin-Borne Volatile Markers of Entrapped Humans by Selective Reagent Ionization Time of Flight Mass Spectrometry in NO+ Mode

“…Recent employing of a time-of-flight (TOF) mass filter in the proton transfer reaction-mass spectrometry (PTR-MS) instruments considerably increased their resolving power (up to 5000 m /Δ m ) and, thereby, the separation and identification of isobaric compounds. 14,15 Moreover, the analytical power of the PTR-TOF-MS can be further enhanced by employing different precursor ions instead of H 3 O + such as NO + , O 2 + , or Kr + (selective reagent ionization time-of-flight mass spectrometry (SRI-TOF-MS)). 15,16 Such an approach can help in many cases to separate functional isomers.…”