Seasonal variations of chronic hemodialysis dose in South Croatia

Introduction: The dialysis parameters are used for prescribing the dose of dialysis therapy. Delivered dialysis dose could be calculated from predialysis and postdialysis blood urea concentrations. Seasonal variations in some clinical and laboratory variables occur among chronic hemodialysis patients. Seasonal variations in chronic hemodialysis dose have not been investigated. We prospectively compared hemodialysis adequacy parameters in order to demonstrate its seasonal differences. Subjects and methods: Data were processed on 201 single dialysis treatments involving a group of 51 anuric chronic hemodialysis patients. The study period was 12 months. Four measurements per subject were obtained (in January, April, July, and October). Results: We could not demonstrate seasonal variability in prescribed and delivered hemodialysis dose, in "delta" values (absolute differences between prescribed and delivered dialysis doses for the same hemodialysis treatment), or in ultrafiltration per hemodialysis. Seasonal differences were found in blood urea concentrations before and after hemodialysis (p=0.001, p=0.010). When the data were grouped into two groups: cold (January and October) and mild (April and July) months; we could not demonstrate significant differences in dialysis adequacy parameters, but there were differences in blood urea concentration before hemodialysis (26.06′14.73 vs. 24.35′4.50, p=0.004), blood urea concentration alter hemodialysis (10.24′2.96 vs. 9.43′2.60, p=0.019), and ultrafiltration per hemodialysis (3.36′1.13 vs. 3.10′1.11, p=0.046). Conclusion: Based of the results of this investigation conducted on chronically hemodialyzed patients in the mild Mediterranean climate in South Croatia, Europe; we have concluded that clinicians should not pay attention to season when they prescribe hemodialysis dose or analyze delivered hemodialysis dose.