title: The impact of low serum sodium level on mortality depends on glycemic control.
abstract: BACKGROUND
  Low serum sodium levels have been associated with mortality both in patients with and without chronic kidney disease. In this study, we investigated this association in relation to glycemic control in hemodialysis (HD) patients.
  
  
  METHODS
  Between March and September 2005, 697 prevalent HD patients were enrolled in this prospective observational study and followed up for all-cause and cardiovascular mortality. The associations of serum sodium concentration with both overall and cardiovascular survival rates were studied.
  
  
  RESULTS
  At baseline, mean predialysis serum sodium concentration was 138.4 ± 2.3 mEq/L (range: 130-145 mEq/L). Mild hyponatremia (< 135 mEq/L) was present in only 41 subjects (5.9%), and no patient had serum sodium level < 130 mEq/L. During 20.2 ± 6.2 months of follow-up, 119 patients (15.9%) died, 68 from CV causes. In adjusted Cox regression analysis, lowest sodium quartile was associated with 2.13-fold increased risk of overall mortality (95% confidence interval (CI) 1.14-3.98, P = 0.01, model chi-square 114.6, P < 0.001). As a continuous variable, each 1 mEq/L increase in predialysis sodium concentration was associated with a hazard ratio (HR) of 0.87 for overall mortality (95% CI 0.81-0.95, P = 0.002) and 0.86 for cardiovascular mortality (95% CI 0.78-0.96, P = 0.007). The predictivity of low serum sodium was prominent in diabetic subjects but not in nondiabetics. However, relationship between serum sodium and patient survival in diabetics was lost after adjustment for the HbA1c level: HR 0.91 (95% CI 0.78-1.05, P = 0.20).
  
  
  CONCLUSIONS
  Low serum sodium concentration is associated with mortality only in those with diabetes. Furthermore, the impact of serum sodium on survival in these patients seems to be derived from poor glucose control.
authors: Division of Nephrology, Ataturk Traning and Research Hospital, Izmir, Turkey. drosahin@yahoo.com
authors: Osman Z
authors: OZ
authors: Sahin
authors: Gulay
authors: G
authors: Asci
authors: Fatih
authors: F
authors: Kircelli
authors: Mumtaz
authors: M
authors: Yilmaz
authors: Soner
authors: S
authors: Duman
authors: Mehmet
authors: M
authors: Ozkahya
authors: Cengiz
authors: C
authors: Dogan
authors: Ali R
authors: AR
authors: Odabas
authors: Mustafa
authors: M
authors: Cirit
authors: Ercan
authors: E
authors: Ok
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000150:complications / Q000401:mortality*; D003920:Diabetes Mellitus / Q000097:blood / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007010:Hyponatremia / Q000401:mortality*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D006435:Renal Dialysis; D012964:Sodium / Q000097:blood*; D015996:Survival Rate
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D012964:Sodium; C517652:hemoglobin A1c protein, human