Comparison of 8.4% Sodium Bicarbonate vs. 3% Sodium Chloride in Severe Hyponatremia: A Retrospective Cohort Study

Management of severe hyponatremia requires rapid correction with 100-150 mL of 3% sodium chloride (HTS), but the lack of commercially available, ready-to-use HTS doses may contribute to delays and dosing errors. In contrast, 8.4% sodium bicarbonate (HTB) is available as a 50 mL prefilled syringe and provides a comparable sodium load, though it is not a guideline-endorsed intervention. This study evaluated whether HTB produces a serum sodium increase comparable to HTS.

The primary purpose of this retrospective cohort study was to determine the number of patients whose serum sodium concentrations increased ≥ 4 mEq/L following administration of HTB or HTS. Patients were included if they were adults, had an initial serum sodium concentration ≤ 120 mEq/L, and received a single dose of HTB (50 mL) or HTS (100 mL) from January 2019 through December 2024.

A total of 21 patients were included in each group. The number of patients whose post-intervention serum sodium concentration increased by ≥ 4 mEq/L in the HTB and HTS groups was 10 (48%) and 2 (10%), respectively (p = 0.01). The median (IQR) change in serum sodium concentrations following study drug administration in the HTB and HTS groups was 3 mEq/L (1 to 5) and 0 mEq/L (-0.5 to 2), respectively (p = 0.005). There were no significant differences between the groups in the change in serum bicarbonate concentrations, chloride concentrations, and anion gap levels following study drug administration. No osmotic demyelination syndrome events were reported in the total population.

This study found that a single 50 mL dose of HTB more often resulted in obtainment of guideline-recommended post-intervention serum sodium goal concentrations than a 100 mL HTS dose. Additional studies are needed to confirm these findings and provide a more comprehensive assessment of safety and efficacy outcomes.