Hyponatremia, hypernatremia, and mortality in patients with chronic kidney disease with and without congestive heart failure.
BACKGROUND
Hyponatremia is common in patients with conditions such as congestive heart failure and is associated with increased mortality in hospitalized patients. Congestive heart failure is common in patients with chronic kidney disease, but the association of serum sodium concentration with mortality in such patients is not well characterized.


RESULTS
We examined the association of serum sodium concentration with all-cause mortality in a nationally representative cohort of 655 493 US veterans with non-dialysis-dependent chronic kidney disease (95 961 [15%] of them with congestive heart failure). Associations were examined in time-dependent Cox models with adjustment for potential confounders. During a median follow-up of 5.5 years, a total of 193 956 patients died (mortality rate, 62.5/1000 patient-years; 95% confidence interval, 62.2-62.8). The association of serum sodium level with mortality was U-shaped, with the lowest mortality seen in patients with sodium level of 140 mEq/L and with both lower and higher levels showing significant associations with increased mortality. Patients with serum sodium levels of <130, 130 to 135.9, 145.1 to 150, and ≥150 mEq/L compared with 136 to 145 mEq/L had multivariable-adjusted mortality hazard ratios (95% confidence interval) of 1.93 (1.83-2.03), 1.28 (1.26-1.30), 1.33 (1.28-1.38), and 1.56 (1.33-1.83) (P<0.001 for all). The associations remained consistent in subgroups of patients with and without congestive heart failure.


CONCLUSIONS
Both lower and higher serum sodium levels are independently associated with higher mortality in patients with non-dialysis-dependent chronic kidney disease, irrespective of the presence or absence of congestive heart failure.
Division of Nephrology, Salem Veterans Affairs Medical Center, 1970 Roanoke Blvd, Salem, VA 24153, USA. csaba.kovesdy@va.gov
Csaba P
CP
Kovesdy
Evan H
EH
Lott
Jun Ling
JL
Lu
Sandra M
SM
Malakauskas
Jennie Z
JZ
Ma
Miklos Z
MZ
Molnar
Kamyar
K
Kalantar-Zadeh
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002908:Chronic Disease; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000453:epidemiology* / Q000401:mortality*; D006801:Humans; D006955:Hypernatremia / Q000097:blood / Q000150:complications*; D007010:Hyponatremia / Q000097:blood / Q000150:complications*; D015994:Incidence; D007674:Kidney Diseases / Q000097:blood / Q000453:epidemiology* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood; D015996:Survival Rate
D015415:Biomarkers; D012964:Sodium