Predictive factors for high mortality in hypernatremic patients

Hypernatremia (serum sodium level of > 145 mEq/L) is associated with high mortality. This study reports an analysis of mortality in 116 patients with hypernatremia from two large university-affiliated teaching hospitals. The purpose was to identify factors predictive of high mortality in hypernatremic patients. Medical records were reviewed to obtain the following data: serum sodium (Na+) levels; systolic (S) and diastolic (D) blood pressure (BP) at the time of admission and throughout the hospital course; status of cognitive function; and type of fluid administered. The patients were divided into two groups: expired and survived. Seventy-seven of 116 patients (66%) expired, while 39 patients (34%) survived and were discharged from the hospital. The mean age and gender for patients who died (70.9 +/- 15.4 years, 90% men) were not different from those who survived (66.4 +/- 17.3 years, 87% men). For the serum Na+ levels recorded at three different times (early, peak, and late), mean late serum Na+ level during hospital course was significantly higher in patients who died than in those who survived (151.2 +/- 9.2 v 143.1 +/- 8.0 mEq/L, respectively; P < .001). Mean admission serum Na+ level (154.9 +/- 5.5 v 155.1 +/- 7.7 mEq/L, respectively) and mean peak serum Na+ level (157.5 +/- 6.5 v 156.8 +/- 9.4 mEq/L, respectively) were not different between the two groups. Both SBP and DBP at the time of admission (P < .05) and throughout the hospital course (P < .001) were significantly lower in the patients who died than in those who survived. The cognitive abnormalities consisting of confusion, obtundation, and speech abnormality were significantly (P < .05) higher in the expired patients than in those who survived. Normal (isotonic) saline was used significantly more frequently (P < .00001) in patients who expired than in those who survived. Thus, this study suggests that a persistently elevated serum Na+ level (possibly caused by prolonged infusion of normal saline) in association with protracted hypotension portends a dismal prognosis in hospitalized hypernatremic patients.