Assessing Cross-Sectional Association of Uremic Pruritus with Serum Heavy Metal Levels: A Single-Center Study

(1) Background: Uremic pruritus (UP) is a common and taxing symptom in patients on maintenance hemodialysis (MHD). We have previously shown that blood lead levels (BLLs) and blood aluminum levels (BALs) were separately positively associated with UP in MHD patients. We also found that blood cadmium levels (BCLs) were positively associated with all-cause mortality and cardiovascular-related mortality in MHD patients. We wondered whether there is any correlation between BCLs and UP after adjusting for BLLs and BALs. (2) Methods: Patients enrolled in this study were all from three hemodialysis (HD) centers at Chang Gung Memorial Hospital, Lin-Kou Medical Center, including both the Taipei and Taoyuan branches. Correlations between UP and BLLs, BALs, BCLs, and other clinical data were analyzed. (3) Results: Eight hundred and fifty-three patients were recruited. Univariate logistic regressions showed that diabetes mellitus, hepatitis B virus infection, hepatitis C virus infection, HD duration, hemodiafiltration, dialysis clearance of urea, normalized protein catabolic rate, non-anuria, serum albumin levels, log (intact-parathyroid hormone levels), total serum cholesterol levels, serum low-density lipoprotein levels, log (blood aluminum levels), and log (blood lead levels) were associated with UP. Although log BCLs were not significantly associated with UP (p = 0.136) in univariate analysis, we still included log BCLs in multivariate logistic regression to verify their effect on UP given that our aim in this study was to verify associations between serum heavy metals and UP. Multivariate logistic regressions showed that log BLLs (OR: 27.556, 95% CI: 10.912-69.587, p < 0.001) and log BALs (OR: 5.485, 95% CI: 2.985-10.079, p < 0.001) were positively associated with UP. The other logistic regression, which stratified BLLs and BALs into high and low BLLs and BALs, respectively, showed that high BLLs or high BALs (low BLLs and low BALs as reference) (OR: 3.760, 95% CI: 2.554-5.535, p < 0.001) and high BLLs and high BALs combined (low BLLs and low BALs as reference) (OR: 10.838, 95% CI: 5.381-21.828, p < 0.001) were positively correlated with UP. (4) Conclusions: BLLs and BALs were positively correlated with UP. BCLs were not correlated with UP. Clinicians should pay more attention to the environmental sources of lead and aluminum to prevent UP.