title: Seasonal variations of clinical and biochemical parameters in chronic haemodialysis.
abstract: BACKGROUND
  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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Dr Vedran Kovacic, Ivana Gundulica 3a, 21220 Trogir, Croatia. vedkovac@inet.hr
authors.forename: V
authors.initials: V
authors.lastname: Kovacic
authors.forename: V
authors.initials: V
authors.lastname: Kovacic
mesh_terms: D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy; D008297:Male; D019083:Mediterranean Region; D011446:Prospective Studies; D006435:Renal Dialysis; D012621:Seasons