Dysnatremia is a predictor for morbidity and mortality in hospitalized patients with COVID-19

Tzoulis, Ploutarchos; Waung, Julian A; Bagkeris, Emmanouil; Hussein, Ziad; Biddanda, Aiyappa; Cousins, John; Dewsnip, Alice; Falayi, Kanoyin; McCaughran, Will; Mullins, Chloe; Naeem, Ammara; Nwokolo, Muna; Quah, Helen; Bitat, Syed; Deyab, Eithar; Ponnampalam, Swarupini; Bouloux, Pierre-Marc; Montgomery, Hugh; Baldeweg, Stephanie E

BACKGROUND: Dysnatremia is an independent predictor of mortality in patients with bacterial pneumonia. There is paucity of data about the incidence and prognostic impact of abnormal sodium concentration in patients with coronavirus disease 19 (COVID-19). METHODS: This retrospective longitudinal cohort study, including all adult patients who presented with COVID-19 to two hospitals in London over an 8-week period, evaluated the association of dysnatremia (serum sodium < 135 or > 145 mmol/L, hyponatremia and hypernatremia, respectively) at several timepoints with inpatient mortality, need for advanced ventilatory support and acute kidney injury (AKI). RESULTS: The study included 488 patients (median age 68 years). At presentation, 24.6% of patients were hyponatremic, mainly due to hypovolemia, and 5.3% hypernatremic. Hypernatremia two days after admission and exposure to hypernatremia at any timepoint during hospitalization were associated with a 2.34-fold (95% CI 1.08 – 5.05, p=0.0014) and 3.05-fold (95% CI 1.69 – 5.49, p<0.0001), respectively, increased risk of death compared to normonatremia. Hyponatremia at admission was linked with a 2.18-fold increase in the likelihood of needing ventilatory support (95% CI 1.34-3.45, p= 0.0011). Hyponatremia was not a risk factor for in-hospital mortality, except for the subgroup of hypovolemic hyponatremia. Sodium values were not associated with the risk for AKI and length of hospital stay. CONCLUSION: Abnormal sodium levels during hospitalization are risk factors for poor prognosis, with hypernatremia and hyponatremia being associated with a greater risk of death and respiratory failure, respectively. Serum sodium values could be used for risk stratification in patients with COVID-19.