Serum sodium correction rate and the outcome in severe hyponatremia.

STUDY OBJECTIVE: We investigated the serum sodium correction rate on length of hospitalization and survival rate, in severe chronic hyponatremic patients at the Emergency Department (ED).

DESIGN: An observational study using clinical chart review.

SETTING: The ED of the University Hospital of Marcianise, Caserta, Italy with approximately 30,000 patients visits a year.

TYPE OF PARTICIPANTS: We reviewed sixty-seven patients with severe hyponatremia subdivided in 2 subgroups: group A consisting of 35 patients with serum sodium correction rate<0.3mmol/h and group B consisting of 32 patients with serum sodium correction rate between <0.5 and ≥0.3mmol/h.

INTERVENTION: Emergency patients were evaluated for serum sodium correction rate for hyponatremia by clinical chart review.

MEASUREMENTS AND MAIN RESULTS: Severe hyponatremia was defined as a serum sodium level<120mmol/l. Mean serum sodium correction rate of hyponatremia was of 0.17±0.09% in group A and 0.41±0.05% in group B (p<0.001 vs group A). The length of hospital stay was 10.7±3.7days for group A, and it was significantly decreased to 3.8±0.4days for group B (p<0.005 vs group A). In addition we observed that correction rate of hyponatremia in group A was associated with a significantly lower survival rate (25%) in comparison to group B (60%) (p<0.001 vs group A).

CONCLUSION: We observed that serum sodium correction rate ≥0.3 and <0.5mmol/h was associated with a shorter length of hospital stay and a major survival rate.