Introduction: Seasonal variations in clinical and laboratory variables occur commonly among chronic haemodialysis patients. In order to demonstrate seasonal differences, we prospectively compared biochemical and clinical parameters in a group of chronically haemodialysed patients living in South Croatia, a region with a Mediterranean climate.Materials and Methods: Data were processed on 135 single dialysis treatments involving a group of 34 anuric chronic haemodialysis (HD) patients. Outcomes were measured at 3-month intervals, in March, June, September and December. Results: The seasonal differences were found in phosphorus (P = 0.001), creatinine before HD (P <0.001), creatinine after HD (P = 0.005), alkaline phosphatase (P = 0.012), alanine aminotransferase (P = 0.042), urea before HD (P = 0.039), albumins (P <0.001), total cholesterol (P <0.001), low-density lipoprotein (LDL) cholesterol (P <0.001), high-density lipoprotein (HDL) cholesterol (P <0.001), glucose (P = 0.033), and ultrafiltration per HD (P = 0.037). When the data were grouped into cold (March and December) and mild (June and September) months, we found differences in phosphorus (1.48 ± 0.47 versus 1.72 ± 0.51, P = 0.005), alkaline phosphatase (119.46 ± 69.03 versus 169.78 ± 107.98, P = 0.002), urea before HD (27.13 ± 5.35 versus 24.40 ± 5.99, P = 0.006), albumins (37.92 ± 5.17 versus 40.58 ± 5.69, P = 0.006), total cholesterol (4.93 ± 0.93 versus 5.30 ± 0.93, P = 0.023), LDL cholesterol (2.85 ± 1.04 versus 3.23 ± 0.87, P = 0.046), glucose (4.62 ± 1.15 versus 5.57 ± 1.46, P = 0.004), and ultrafiltration per HD (3.57 ± 1.18 versus 2.97 ± 1.20, P = 0.004). Conclusion: In Mediterranean climates, seasonal differences in predialysis urea concentration and ultrafiltration rate per dialysis could be attributed to different food and water intake. The seasonal differences in blood concentration of phosphorus, alkaline phosphatase, total cholesterol, LDL cholesterol, and glucose might be the results of neurohormonal influences. This climate has no impact on haemoglobin and blood pressure levels.
Seasonal variations in the general population in some body functions and diseases incidences have been well-established (e.g., vitamin D levels, allergic rhinitis, blood pressure, levels of physical activity and energy expenditure, mental depression, peptic ulcer disease, and death from chronic heart failure). Similar patterns of seasonal variations in some clinical and laboratory variables occur commonly among chronic haemodialysis patients and these variables correlate mostly with ambient temperature and relative humidity.
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