Hemodialysis-Associated Asymmetry in Serum Zinc Concentrations Measured by ICP-MS: A Paired Observational Clinical Study

Zinc (Zn) homeostasis is frequently altered in patients with advanced chronic kidney disease undergoing maintenance hemodialysis (HD); however, acute intraindividual changes in circulating Zn during a single HD session remain insufficiently characterized. This study evaluated HD-associated asymmetry in serum Zn concentrations using paired pre- and post-HD measurements. This cross-sectional observational study with a paired pre–post analytical component included 40 adults receiving maintenance HD at a secondary-care public hospital in Mexico. Serum Zn was quantified immediately before and after a routine hemodialysis session using a validated inductively coupled plasma mass spectrometry (ICP-MS) method operated in helium kinetic energy discrimination (He-KED) mode. Median serum Zn concentrations were lower after hemodialysis than before hemodialysis [64.84, 45.39–108.62 vs. 82.08, 57.45–136.59 µg/dL, respectively (p < 0.001)], demonstrating a significant pre–post asymmetry. This reduction remained significant in both sexes and across nutritional status groups (all p < 0.001). Significant pre–post reductions were also observed in both sexes and across both baseline BMI categories after Benjamini–Hochberg correction (q-BH < 0.05). Baseline serum Zn was not significantly correlated with the evaluated biochemical, anthropometric, or body composition variables after correction for multiple comparisons. These findings indicate an acute hemodialysis-associated asymmetry in circulating Zn and support further longitudinal studies to determine its persistence, underlying mechanisms, and clinical significance.