ECE2016 Guided Posters Pituitary - Clinical (10 abstracts)
Introduction: Hyponatremia is the most common electrolyte abnormality in clinical practice and given its impact on mortality and morbidity a relevant medical condition. Nevertheless little is known about factors influencing long-term outcome.
Methods: This is a prospective observational 12 months follow-up study of patients with profound hyponatremia (≤125 mmol/l) admitted to the medical emergency department of two tertiary care centers in Switzerland between 2011 and 2013. We analysed the association of different clinical and laboratory parameters with following three outcomes: 1-year-mortality, rehospitalisation and recurrent profound hyponatremia.
Results: Median [IQR] initial serum sodium (s-sodium) level of the 281 patients included (median age 72 years [61-80]) was 120 mmol/l . During the study-period 58 (20.6%) patients died. The majority (56.2%) was hospitalized at least once again, 28.5% even repeatedly. Recurrent hyponatremia was observed in 42.7%, being profound again in 16%. Beside relevant comorbidities (assessed by the Charlson Comorbidity Index) the following two parameters revealed significant association with the main outcome mortality also after multivariate adjustment: initial s-sodium level (Odds Ratio [OR] 1.14, 95% Confidence Interval [CI] 1.01-1.29, P=0.036) and corrected s-sodium ≥135 mmol/l at discharge (OR 0.47, 95% CI 0.230.94, P=0.034).
Severity of hyponatremia showed an inverse correlation with mortality. Thus, we compared patients with s-sodium levels ≤120 mmol/l to those with levels >120 mmol/l; the latter had a significant higher mortality rate than patients with lower s-sodium levels (27.8% vs 14.8%, P=0.0078). Also etiology of hyponatremia differed: patients with s-sodium level ≤120 mmol/l were more likely to have drug induced hyponatremia (49% vs 29.4%, P=0.0008), whereas hypervolemic hyponatremia was more common in patients with initial s-sodium level above 120 mmol/l (15.9% vs 7.7%, P=0.033).
Conclusion: Hyponatremia goes along with a high 1-year-mortality, recurrence and rehospitalisation rate. The inverse correlation of hyponatremia-severity and mortality emphasizes the importance of the underlying disease, which rather determines outcome than hyponatremia itself.