Uraemic pruritus is not related to plasma histamine concentrations.

Pruritus is a common symptom in uraemic patients and its aetiology is poorly understood, although several factors have been implicated, including high histamine plasma levels. The aim of the study was to evaluate plasma levels of histamine in patients on maintenance haemodialysis in relation to the presence of itching (35 pruritic patients = group A; 50 non-pruritic patients = group B). Furthermore, we compared the values obtained with those of a healthy control group (64 subjects). We observed increased plasma histamine levels in uraemic patients compared with healthy controls. However, no relationship was found between plasma histamine values and itching because groups A and B showed overlapping values and there was no correlation between the intensity of pruritus and plasma histamine concentrations in group A patients. In conclusion, we suggest that there is no evidence for plasma histamine playing a significant part in uraemic pruritus.