Risk of Suboptimal Serum Sodium Correction According to Etiology in Severe Hyponatremia

Achieving an appropriate serum sodium correction rate in hyponatremia is essential but remains challenging. Given that the rate of correction in hyponatremia may vary by underlying etiology, understanding this relationship could help optimize clinical management, but it remains insufficiently explored. To address this, we aimed to evaluate whether the risk of suboptimal correction varies across different etiological categories.

This retrospective observational study included patients with severe hyponatremia (serum sodium level ≤120 mEq/L) at admission or during hospitalization at two tertiary care centers between January 2014 and June 2024. Patients were classified into nine etiological categories: kidney losses, non-kidney losses, syndrome of inappropriate antidiuresis (SIAD), adrenal insufficiency, low solute intake, polydipsia, heart failure, cirrhosis, and kidney disease. The association of etiological categories and the incidence of rapid (≥10 mEq/L) or slow (≤5 mEq/L) serum sodium correction within the initial 24 hours was assessed.

Among the 876 patients included, the median (interquartile range) age was 73 (62-82) years. The baseline serum sodium level was 118 (115-119) mEq/L, and the 24-hour correction rate was 4.8 (1.7-7.8) mEq/L. Logistic regression analysis revealed that, compared to SIAD, polydipsia (odds ratio [OR], 10.3; 95% confidence interval [CI], 4.81-22.0), adrenal insufficiency (OR, 5.32; 95% CI, 2.29-12.4), non-kidney losses (OR, 3.25; 95% CI, 1.38-7.66), and low solute intake (OR, 3.15; 95% CI, 1.73-5.76) were associated with rapid correction. Cirrhosis (OR, 2.24; 95% CI, 0.92-5.49), heart failure (OR, 1.79; 95% CI, 0.84-3.83), and kidney losses (OR, 1.48; 95% CI, 0.86-2.55) showed a tendency toward slower sodium correction.

Correction rates varied by underlying etiology in severe hyponatremia. Etiological assessment may help predict correction rates and optimize management strategies in clinical practice.