Onset, time course, and persistence of increased haemodialysis-induced breath isoprene emission

Recent findings of increased isoprene emission in the exhaled breath of patients undergoing haemodialysis and experimental evidence of the potential toxic and cancerogenic effects of isoprene hydrocarbon led us to assess how long haemodialysis patients are exposed to how much isoprene after a single haemodialysis session. Patients with end-stage renal failure on regular 4-hour (from 08.00 to 12.00 h) maintenance haemodialysis three times weekly were monitored. The breath isoprene content was analyzed by gas chromatography. Intrapatient evaluations were performed by collecting samples before, during, and immediately after the haemodialysis session, during the following hours, and on the following nondialysis day. The breath isoprene content increased in all patients. Isoprene overproduction showing a biphasic pattern was first detected soon after the dialysis session ended. These data show that haemodialyzed patients seem to be consistently exposed to high endogenous isoprene concentrations. The mechanisms and implications of this endogenous isoprene overproduction need to be elucidated with regard to the mevalonic pathway and in the physiopathological setting of the uraemia-dialysis syndrome.