Serum copeptin levels in stage 3–4 chronic kidney disease and maintenance hemodialysis: a cross-sectional study

Abstract Objective Chronic kidney disease (CKD) is characterized by progressive decline in glomerular filtration rate (GFR) and is associated with activation of neurohormonal pathways, including the arginine vasopressin system. Copeptin, the C-terminal fragment of pre-pro-vasopressin, has emerged as a stable surrogate marker of vasopressin activity. This cross-sectional study compared serum copeptin levels across clinically distinct study groups and evaluated their associations with renal and biochemical parameters. Methods The study included 120 participants: 30 healthy controls and 90 patients with CKD, comprising stage 3 CKD, stage 4 CKD, and end-stage kidney disease (ESKD) receiving maintenance hemodialysis groups ( n = 30 each). In patients receiving maintenance hemodialysis, fasting blood samples were obtained immediately before the scheduled dialysis session. Serum copeptin concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). Renal function was assessed using 24-hour urinary creatinine clearance; in patients receiving maintenance hemodialysis, these values were interpreted as approximate estimates of residual kidney function. Intergroup comparisons were performed using one-way ANOVA, and correlations were analyzed using Pearson’s test. A two-tailed p value < 0.05 was considered statistically significant. Results Serum copeptin levels were significantly higher in the hemodialysis group than in the control, stage 3 CKD, and stage 4 CKD groups (overall p < 0.001). No significant differences were observed among the control, stage 3 CKD, and stage 4 CKD groups. Copeptin was negatively correlated with 24-hour urinary creatinine clearance ( r = − 0.237, p < 0.01) and positively correlated with creatinine, parathyroid hormone, and glucose. No significant correlations were observed with C-reactive protein, calcium, phosphorus, or urea. Conclusion In this cohort, copeptin levels were significantly elevated in patients receiving maintenance hemodialysis, whereas no significant differences were observed between controls and patients with stage 3 or stage 4 CKD. Because non-dialysis stage 5 CKD was not evaluated, these findings should be considered exploratory. Larger prospective studies incorporating appropriate multivariable analyses and longitudinal follow-up are required to clarify the significance of copeptin in CKD.