Uremic pruritus in patients on hemodialysis or continuous ambulatory peritoneal dialysis (CAPD). The role of plasma histamine and skin mast cells.

Fifty-four uremic patients (26 patients were maintained on continuous ambulatory peritoneal dialysis [CAPD] and 28 on hemodialysis [HD]) were screened for pruritus and plasma histamine. 50% of the patients on CAPD and 64.3% of patients on HD complained of current itching. The extent of itch, assessed by a score, was not significantly different between HD and CAPD patients. Plasma histamine levels showed no significant difference between CAPD and HD patients and no correlation between plasma histamine level and the extent of pruritus could be demonstrated. In six patients on CAPD and 9 patients on HD plasma histamine levels were determined before and three months after initiation of dialysis treatment; no substantial change could be observed. In some patients skin biopsies were obtained from the gluteal region in order to determine the number of skin mast cells. The number of mast cells did not show a significant difference between controls (n = 12), uremic patients before initiation of dialysis treatment (n = 8), patients on CAPD (n = 11) and patients on HD (n = 13). There was no relationship between the level of plasma histamine, the number of skin mast cells and the extent of pruritus in uremic patients.