Uraemic
pruritus is a frequent and disabling symptom in patients on dialysis. The pathogenesis of uraemic
pruritus is nevertheless still obscure. We investigated whether
di(2-ethylhexyl)phthalate (
DEHP), the most commonly used
plasticizer in polyvinylchloride (
PVC) haemodialysis tubings, is a possible pathogenetic factor in uraemic
pruritus. Serum concentrations of
DEHP and its major derivatives
mono-(2-ethylhexyl)phthalate (
MEHP),
2-ethylhexanol (2-EH) and
phthalic acid (PA) were determined in uraemic patients before and after a haemodialysis session and compared with the occurrence and intensity of
pruritus in these patients. Twenty-one patients on regular haemodialysis for at least 6 months were examined. The severity of uraemic
pruritus was assessed using a standard questionnaire (
pruritus score). The quantitative analysis of
DEHP and its derivatives was carried out by GC/selected ion monitoring mass spectrometry. Fourteen out of 21 patients (66%) complained about uraemic
pruritus to a variable degree. The post-dialysis serum concentrations of
DEHP,
MEHP and 2-EH were significantly higher than the corresponding pre-dialysis values, whereas the post-dialysis concentrations of PA (0.122 +/- 0.078 microgram/microliter) were significantly lower than pre-dialysis levels (0.194 +/- 0.101 microgram/microliter, P = 0.00068). Neither pre- nor post-dialysis serum concentrations of
DEHP,
MEHP, PA or 2-EH were correlated with the severity of uraemic
pruritus. Additionally, serum concentrations of
DEHP and its metabolites did not differ significantly in patients with and without
pruritus. These findings suggest that patients on haemodialysis are regularly exposed to considerable amounts of
DEHP and metabolites.
Phthalic acid, one of the presumed end products of
DEHP metabolism, might be eliminated at least in part by haemodialysis. The exposition to
DEHP and metabolites during haemodialysis, as assessed by measuring serum concentrations, bears no immediate relation to the occurrence or intensity of uraemic
pruritus.