title: Uraemic itching: do polymethylmethacrylate dialysis membranes play a role?
abstract: BACKGROUND
  Patients undergoing chronic renal replacement therapy by haemodialysis (HD) suffer from chronic itching, the prevalence of which is very high. Many of the available treatment options are ineffective, but, as it has been shown that Polymethylmethacrylate based dialysis membranes (PMMA) membranes remove a wide range of 'middle molecules' and improve such long-term complications of HD as carpal tunnel syndrome and malnutrition, they may also have an effect on uraemic itching.
  
  
  METHODS
  This prospective study enrolled eight patients undergoing standard HD with low-flux synthetic membranes and suffering from chronic itching. The strength and duration of itching was evaluated by the patients themselves at each study time-point using a visual analogue scale (VAS). After a baseline evaluation, the patients were switched to a PMMA membrane for 6 months during which their pre-dialysis haemoglobin, haematocrit, total protein, albumin, urea, creatinine, phosphate, intact parathyroid hormone (i-PTH), serum bile acid, beta2-microglobulin, C-reactive protein (CRP) levels, and eKt/V were measured, and any general complaints were recorded.
  
  
  RESULTS
  The self-assessed VAS itching strength scores decreased by 15% after 1 month, 30% after 2 months, and 55% after 6 months, and itching duration decreased by, respectively, 10, 22 and 44% at the same time; 2 months after the end of the study, both scores had slightly increased. There were no statistically significant differences in the pre-dialysis blood chemistry values or eKt/V at the four study time-points, but beta2-microglobulin levels significantly decreased (P < 0.03); the decrease in CRP levels was not significant (P < 0.06). Furthermore, four patients showed a trend towards a lower incidence of intradialytic hypotension.
  
  
  CONCLUSIONS
  These findings support the hypothesis that a PMMA dialyser may improve renal itching in ESRD patients. This effect is not mediated by increased dialysis efficiency or an improvement in other biochemical parameters, but we can speculate that ionic substances may be directly or indirectly adsorbed into the polymer composition of BG-U series (PMMA membrane dialyser). We are currently undergoing further studies using a proteomic approach.
authors.affiliation: Dialysis Unit, F. Lastaria Hospital, ASL Provincia di Foggia, Viale Lastaria, 71036 Lucera (FG), Italy. faucel1@alice.it
authors.forename: Filippo
authors.initials: F
authors.lastname: Aucella
authors.forename: Mimmo
authors.initials: M
authors.lastname: Vigilante
authors.forename: Antonio
authors.initials: A
authors.lastname: Gesuete
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Maruccio
authors.forename: Angelo
authors.initials: A
authors.lastname: Specchio
authors.forename: Loreto
authors.initials: L
authors.lastname: Gesualdo
mesh_terms: D000368:Aged; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D010147:Pain Measurement; D019904:Polymethyl Methacrylate; D011446:Prospective Studies; D011537:Pruritus / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control*; D006435:Renal Dialysis / Q000009:adverse effects* / Q000295:instrumentation*; D012720:Severity of Illness Index; D013997:Time Factors; D014511:Uremia / Q000097:blood / Q000628:therapy*; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D008567:Membranes, Artificial; D001613:beta 2-Microglobulin; D002097:C-Reactive Protein; D019904:Polymethyl Methacrylate