The impact of the correction of hyponatremia during hospital admission on the prognosis of SARS-CoV-2 infection.

Introduction: SARS-CoV-2 infection is frequently associated with hyponatremia (plasma sodium<135mmol/L), being associated with a worse prognosis. The incidence of hyponatremia is estimated to be 20-37% according to the series, but there are no data on the prognosis after correction of hyponatremia. Therefore, our objectives were: to analyze the incidence and severity of hyponatremia at hospital admission, and to determine the association of this hyponatremia with the prognosis of COVID-19.

Material And Method: Observational and retrospective cohort study. Patients who were admitted with a diagnosis of COVID-19 infection and hyponatremia, in the period March-May 2020, were included. We recorded epidemiological, demographic, clinical, biochemical, and radiological variables of SARS-CoV-2 infection and hyponatremia at the time of diagnosis and during hospitalization. The clinical follow-up ranged from admission to death or discharge.

Results: 91 patients (21.8%) of the 414 admitted for SARS-CoV-2 infection presented hyponatremia (81.32% mild hyponatremia, 9.89% moderate and 8.79% severe). The absence of correction of hyponatremia 72-96h after hospital admission was associated with higher mortality in patients with COVID-19 (Odds Ratio .165; 95% confidence interval: .018-.686; P=.011). 19 patients (20.9%) died. An increase in mortality was observed in patients with severe hyponatremia compared with moderate and mild hyponatremia during hospital admission (37.5% versus 11.1% versus 8.1%, P=.041).

Conclusions: We conclude that persistence of hyponatremia at 72-96h of hospital admission was associated with higher mortality in patients with SARS-CoV-2.