Corrected Sodium Levels for Hyperglycemia is a Better Predictor than Measured Sodium Levels for Clinical Outcomes among Patients with Extreme Hyperglycemia

BACKGROUND Abnormal serum sodium levels in various diseases increase mortality; however, hyperglycemia depresses serum sodium concentration significantly. This study aimed to evaluate the clinical impact of measured serum sodium levels and corrected sodium levels among patients with severe hyperglycemia. METHODS Patients with blood glucose levels ≥500 mg/dL visiting the emergency department between July 2008 and September 2010 were enrolled retrospectively. The participants were divided into five groups for measured sodium levels and five groups for corrected sodium levels according to blood glucose levels. Multivariate Cox regression was used. The primary outcome was all-cause 90-day mortality. Secondary outcomes included rate of intensive care unit hospitalization, respiratory failure, and renal failure. RESULTS A total of 755 patients with severe hyperglycemia were enrolled, and the 90-day mortality was 17.2%. Compared with the reference group, the 90-day mortality was higher in the patients with measured hypernatremia (adjusted hazard ratio [HR], 2.86; 95% confidence interval [CI], 1.39-5.87), corrected hyponatremia (adjusted HR, 3.56; 95% CI, 1.44-8.80), and severe corrected hypernatremia (adjusted HR, 2.68; 95% CI, 1.28-5.62). However, patients with severe measured hyponatremia did not show increased mortality (adjusted HR, 1.67; 95% CI, 0.84-3.32). CONCLUSION Among patients with severe hyperglycemia, corrected sodium level is a better indicator of clinical outcomes compared with measured sodium levels, especially in this population with measured hyponatremia.