Substance P and intensity of pruritus in hemodialysis and peritoneal dialysis patients

BACKGROUND Uremic pruritus is a common complication in patients undergoing dialysis. The pathophysiological mechanisms of pruritus in patients with end-stage renal disease remain unknown. Neuropeptides, including substance P, are postulated to play an important role in the pathogenesis of pruritus. The aim of this study was to evaluate the role of substance P in uremic pruritus in patients on hemodialysis and peritoneal dialysis. MATERIAL/METHODS We included 197 patients with end-stage renal disease: 54 on continuous ambulatory peritoneal dialysis and 143 on hemodialysis. Substance P, calcium, phosphorus, iron, ferritin, CRP, albumin, hemoglobin, Ca×P product, and iPTH level were determined in all participants. The correlation between these parameters and self-reported itching was evaluated in patients on hemodialysis in comparison with peritoneal dialysis patients. RESULTS The incidence of itching was similar in hemodialysis and peritoneal dialysis patients. No differences in substance P level between the 2 groups were found. There was no correlation between substance P level and the incidence or intensity of pruritus in dialyzed patients. CONCLUSIONS This study demonstrates that substance P does not play any important role in pruritus in hemodialysed and peritoneal dialyzed patients. However, further studies are necessary to assess the exact role of neuropeptides in uremic pruritus.