Background: The measurement of trimethylamine and isoprene in exhaled breath collected from dialysed patients indicates the changes in concentration of both compounds during dialysis. The aim of the presented study was to confirm diagnostic usefulness of TMA and isoprene detected in breath, as potential biomarkers of hemodialysis efficiency.
Methods: The samples of exhaled breath were collected from 22 dialyzed patients (9 women, 13 men) before and after hemodialysis (HD). All analyses were carried out using a gas chromatograph equipped with a mass spectrometer. Thermal desorption was used as breath sample enrichment method.
Results: Chromatographic analysis of breath samples indicated statistically significant differences in trimethylamine (TMA) and 2-methyl-1,3-butadiene (isoprene) concentrations in patients' breath collected before and after HD. TMA concentrations measured in breath samples, before dialysis, ranged from 0.024 to 0.461 nmol/L. After dialysis, the values of detected TMA were lower versus output values and ranged from 0.008 to 0.050 nmol/L. Isoprene concentrations before dialysis were present in the range from 0.236 to 9.718 nmol/L, after dialysis in the range from 0.478 to 26.182 nmol/L. Additionally, the dependences of TMA and isoprene concentrations, detected in breath with renal efficiency parameters detected in blood, were studied. The relationships between TMA and urea (r = 0.67; p < 0.00001) and creatinine (r = 0.61; p = 0.00002) were checked. In case of isoprene considerably higher concentrations were observed after dialysis, but no statistically significant correlation of isoprene with blood parameters was noticed.
Conclusion: The observed decrease of TMA concentrations during dialysis could be useful as a measure of dialysis efficiency. The explanation of isoprene increase in breath during dialysis requires further investigation.
Keywords: Breath test; End stage renal disease (ESRD); Gas chromatography; Hemodialysis; Isoprene; Trimethylamine.