Aim

To review the aetiology, management and outcomes of hyponatraemia in patients treated with hypertonic saline in Western Sydney Local Health District (WSLHD) over a 2 year period. To assess risk factors for rapid sodium correction and poor clinical outcome.

Method

We conducted a retrospective cohort study of patients with serum sodium (Na)<135mmol/L, treated with 3% hypertonic saline at 4 hospitals within WSLHD from January 2022 to December 2024. Variables of interest included baseline Na, neurological symptoms (seizures, headache, altered mentation), aetiology  of hyponatraemia and ICU admission. Rapid Na correction was defined according to European Clinical Practice Guidelines (>10 mmol/24hours). Comparisons were made using student’s t tests.

Results

Of 92 patients, (mean age 66.7 years, female 56.3%, mean Na 113.6mmol/L), seizures (32.5%) and nausea and vomiting (31.5%) were common presentations. SIAD (53.2%) and dehydration (25%) were the commonest causes of hyponatraemia. 29 patients met the definition of rapid correction. The mean baseline Na in the rapid correction group was significantly lower than in those with appropriate correction (110.9 vs 115.1mmol/L, p=0.004). The rapid correction group were also more likely to have ACEI or ARB use (65.5% vs 14.3%, p<0.001) and neurological symptoms on admission (100% vs 84.1%, p=0.02). Diuretics were not a risk factor for rapid Na correction. ICU admission did affect rapid correction compared to non-ICU admission (79.3% vs 71.4%, p=0.42). There were 9 deaths (8 with Na <120mmol/L, 2 with rapid correction) and 1 case of osmotic demyelination syndrome in the rapid correction group. Mortality was higher in patients with CCF (33.4% vs 3.6%, p=0.0006). There was no difference in mortality between rapid and non-rapid correction groups (6.9% vs 11.1%, p=0.53).

Conclusions

Risk factors for rapid Na correction in patients treated with hypertonic saline included lower Na, ACEI or ARB use and neurological symptoms on admission.