Longitudinal trace element monitoring in haemodialysis patients: Impact of dialysis vintage and technical treatment factors.

BACKGROUND: Chronic kidney disease and haemodialysis (HD) profoundly alter essential element homeostasis, causing both deficiencies and toxic metals accumulation. This research aimed to characterise serum trace element status in HD patients compared to healthy controls (CNTRL) and to investigate the time-dependent accumulation and modulation of these elements by clinical and dialysis-related technical factors. MATERIALS AND METHODS: A prospective cross-sectional (HD vs. CNTRL) and two-year longitudinal (HD cohort) study was conducted at a single centre (Alcoy, Spain, 2015-2017). A total of 199 participants (117 HD, 82 CNTRL), matched for age and sex, were included. Serum trace elements were quantified using highly sensitive inductively coupled plasma-mass spectrometry (ICP-MS) after rigorous validation. Cross-sectional differences were analysed using multivariable linear and Tobit regression adjusted for clinical confounders and dialysis-specific variables. Longitudinal changes were assessed using linear mixed-effects models (LMM). RESULTS: HD patients had significantly lower zinc, selenium, and rubidium levels (p < 0.0001) and higher chromium, arsenic, nickel, cobalt, molybdenum, and titanium levels (all p ≤ 0.03). Dialysis vintage ≥12 months was associated with higher accumulation of chromium, nickel, vanadium, and titanium, highlighting a progressive, time-dependent risk. Water calcium ≥1.5 mmol/L correlated with lower levels of nickel and chromium (p ≤ 0.03). The LMM confirmed increasing nickel (p = 0.0006) and decreasing selenium (p = 0.006) over time. CONCLUSION: HD patients suffer profound, progressive dyshomeostasis of trace elements, marked by deficiencies in essential elements and accumulation of toxic metals. These findings underscore the need for systematic monitoring and targeted interventions to optimise essential element status and reduce toxic metal burden.