Volatile alkanes and increased concentrations of isoprene in exhaled air during hemodialysis

In this study we examined breath volatile hydrocarbon concentrations in exh aled air of hemodialysis patients. We assessed both C-2-C-5 alkanes - among them ethane and pentane the production of which in man is essentially due to the action free radicals exert on polyunsaturated fatty acids - and isop rene, an unsaturated hydrocarbon the biosynthesis and biological effects of which are the subject of controversy and mounting interest. Twenty patient s were studied. Evaluation was performed intrapatient in the breath of pati ents with chronic renal failure, before and after dialysis (20 patients) an d, in the same cases, during hemodialytic treatment (10 patients). Breath c oncentrations of these volatile hydrocarbons, determined before dialysis, w ere not different from those of normal subjects. Dialysis did not modify th e levels of the C2-C5 saturated hydrocarbons ethane, propane, butane and pe ntane. Instead, there was a marked increase in isoprene in all patients (ba sal values rose by a mean of 270%). Since isoprene was not present in the f luids or filters used for dialysis and there were only traces in the ambien t air, the isoprene must have been produced endogenously during hemodialysi s. As no situation has previously been reported to increase endogenous prod uction of isoprene in humans, patients in hemodialysis offer a unique oppor tunity to investigate in depth the medical, biological and toxicological as pects of isoprene.