Endocrine Abstracts

Introduction & aim

Hypertonic saline (HTS) is an effective treatment for severe symptomatic hyponatraemia. European Society of Endocrinology (ESE) published guidelines to standardise HTS administration in 2014, however, evidence behind the guidelines is limited by virtue of being largely derived from small retrospective studies and expert opinion. The aim of this study was to evaluate the ’real-world’ safety and efficacy of these guidelines.

Methods

This was a retrospective, observational, cohort study. We examined use of HTS for severe symptomatic hyponatraemia at two University hospitals between 2017–2020 that had uniformly adopted ESE guidance. Patients were identified via a centralised pharmacy database and data was collected to record demographic and clinical variables in addition to treatment details. The primary outcome was rate of overcorrection after first and second HTS boluses (defined as rise in sodium >5 mmol/l), and at 24 and 48 hours (rise in sodium >10 and 18 mmol/l) respectively. Secondary outcomes were inpatient mortality rate, all-cause mortality rate at 12 months, and rate of osmotic demyelination syndrome (ODS).

Results

In total 112 patients (Females: Males = 61:51) met the inclusion criteria for the study. Their mean age ± SD was 66.4 ± 16.0 years with mean body mass index ± SD of 24.8 ± 5.6 kg/m². Mean serum sodium ± SD at baseline was 113.8 ± 6.4 mmol/l. Less than 1/5^th of the patients were administered treatment to mitigate overcorrection (dextrose infusion/desmopressin). Primary outcome: Overcorrection rates after first and second boluses were 22.6% and 34.6%, respectively, while overcorrection rates at 24 and 48 hours were 44.9% and 19.6%, respectively. Secondary outcomes: 7.1% patients died during the same admission, while the mortality at 12 months was 18.7%. No cases of ODS were reported. A bivariate regression analysis including various categorical and continuous variables was unable to define characteristics of a high-risk group. Finally, a significant correlation was noted between paired serum and venous blood gas sodium (n = 36, Spearman’s correlation r = 0.956; P<0.001), although the latter was, on average, 1.9 mmol/l lower than for serum.

Conclusion

This is the first study to comprehensively evaluate ESE guidelines in a real-world setting. Rate of overcorrection at various endpoints is significantly high without long-term sequelae. We recommend liberal use of overcorrection treatments, especially in the first 24 hours, to keep the sodium rise within the suggested cut-offs. Accounting for a correction factor of ~2 mmol/l, a venous gas sodium check between the first two boluses is useful in practice.