Uremic pruritus, cytokines, and polymethylmethacrylate artificial kidney

Uremic pruritus is one of the common complications in long-term dialysis patients. Recently, researchers reported that immunohypothesis with high serum level of cytokines could be the cause of uremic pruritus. Polymethylmethacrylate (PMMA) artificial kidney (AK) has been reported to adsorb more serum cytokines than other high-flux AKs. In July 2006, 30 patients with severe uremic pruritus from 300 chronic hemodialysis (HD) patients in a single center entered this prospective study. Their dialyzers were changed to PMMA AK for 4 weeks. The severity of pruritus was evaluated every week using the results of a questionnaire (pruritus score). Laboratory assays including predialysis serum blood urea nitrogen (BUN), creatinine, beta2-microglobulin (beta2M), calcium, phosphate, intact parathyroid hormone (iPTH), total CO(2), ferritin, hematocrit, high-sensitivity C-reactive protein (hsCRP), IL-1beta, IL-2, IL-6, IL-18, tumor necrosis factor-alpha (TNF-alpha), Kt/V, and beta2M clearance were measured before and at the end of 4 weeks of PMMA AK use. PMMA AK was effective in reducing the pruritus score from 23.46 +/- 11.94 to 7.38 +/- 6.42 (P < 0.001). The effect of uremic pruritus relief appeared after 1 week of PMMA AK use. There were no significant differences in the laboratory assay results including predialysis serum BUN, Cr, beta2M, calcium, phosphate, calcium-phosphate product, iPTH, total CO(2), ferritin, hematocrit, hsCRP, IL-1beta, IL-2, IL-6, IL-18, TNF-alpha, Kt/V, and beta2M clearance. The mechanism for the beneficial effect of PMMA AK on uremic pruritus remains to be determined. PMMA AK may be a useful adjuvant therapy in chronic HD patients with severe uremic pruritus.