Nonlinear association between serum iron levels and moderate-to-severe uremic pruritus in peritoneal dialysis patients: a cross-sectional study

To evaluate the occurrence of uremic pruritus among peritoneal dialysis (PD) patients and explore its correlation with serum iron levels. A cross-sectional study was carried out on 189 PD patients at a single center in China. The severity of pruritus was assessed through the validated 5-D Itch Scale questionnaire. The relationship between clinical factors and pruritus was examined using multivariate logistic regression, restricted cubic spline analysis, piecewise regression, and cluster analysis of iron metabolism patterns. Moderate/severe pruritus affected 27.5% of participants, mainly on lower limbs (52.9%) and back (46.6%). Serum iron was significantly higher in the moderate/severe pruritus group (18.43 ± 8.50 vs. 15.84 ± 6.09 µmol/L, p = 0.029). After adjustments, each standard deviation increase in serum iron corresponded to higher odds of moderate/severe pruritus (odds ratio (OR) = 1.45, 95% confidence interval (CI):1.03–2.08, p = 0.037). Analysis revealed a threshold association(p = 0.043) with an inflection point at 13.7µmol/L, above which each unit increase in serum iron raised pruritus odds by 10% (OR = 1.10, 95%CI:1.03–1.18, p = 0.006). Cluster analysis identified that patients with high transferrin saturation (TSAT), moderate ferritin, and high serum iron had the highest pruritus prevalence (52.8%). In PD patients, we identified a threshold effect of serum iron on uremic pruritus. Iron levels above 13.7 µmol/L independently worsened pruritus, especially in patients with high TSAT, moderate ferritin, and high serum iron, where prevalence reached 52.8%. These findings highlight the importance of assessing iron status and personalized management.