Quantitative Approach for the Treatment of Hypovolemic Hyponatremia in the Emergency Department

Hyponatremia is the most frequent electrolyte derangement in clinical practice and is often associated with dehydration. This happens when the water deficit is combined with a larger solute deficit. This study, carried out in the Emergency Department, was aimed to explore efficacy and safety of two different therapeutic strategies, based on a quantitative approach (AdroguéMadias formula) for treating hyponatremia associated with mild and moderate dehydration. The grade of dehydration was clinically established. Patients moderately dehydrated were treated by setting the desired correction rate at 12 mEq/L/24h to obtain with the formula a larger amount of isotonic saline in order to properly replace a larger volume deficit (Group A, 10 patients); for mildly dehydrated patients the target was set at 6 mEq/L/24h in order to focus treatment on P(Na +) correction (Group B, 12 patients). We analyzed data at baseline and after the first 24 hours of treatment. The median baseline P(Na +) was 126 mEq/L in Group A and 127 mEq/L in Group B (P-value = 0.665); after 24 hours the P(Na +) was significantly higher in both groups, but no statistically significant differences were found between them (132 vs. 134 mEq/L, P-value = 0.355). 59.1% of patients had correction rates within the optimal range (4-8 mEq/ L/24h); no statistically significant differences were observed between groups in the correction kinetics outcome. Therefore, hypovolemic hyponatremic patients may be treated, if required by their volume deficit, with amounts of isotonic saline larger than those predicted by formulas set on international efficacy and safety cut-offs with a negligible risk of overcorrection.