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Abnormal sodium levels predict COVID-19 death or respiratory failure

Hospitalised patients with COVID-19 and abnormal sodium levels in the blood have an increased risk of experiencing respiratory failure or dying, according to a study. "This study shows for the first time that patients presenting at the hospital with COVID-19 and low sodium are twice as likely to need intubation or other means of advanced breathing support as those with normal sodium," said lead investigator Dr Ploutarchos Tzoulis, honorary associate professor in endocrinology at University College London (UCL) Medical School.

Additionally, the researchers found that patients who develop high sodium levels during the hospital stay were three times more likely to die than those who have normal sodium levels throughout hospitalisation.

"Sodium measurements can inform doctors about which COVID-19 patients are at high risk of deterioration and death," Tzoulis said. "Sodium levels can guide decision making about whether a COVID-19 patient needs hospital admission or monitoring in the intensive care unit."

Sodium is routinely measured as part of bloodwork done for all patients coming to the hospital, and its measurement is inexpensive, Tzoulis noted. Sodium is an essential mineral and helps regulate fluid volume in the body and blood pressure.

The study was conducted in 488 adults with COVID-19 admitted to two London hospitals, UCL Hospital and Whittington Hospital, over an eight-week period last year. The 277 men and 211 women had a median age of 68 years. They had a median hospital stay of eight days.

Nearly 32% of COVID-19 patients with low sodium levels at admission needed a breathing tube and ventilator or oxygen through a face mask compared with only 17.5% of patients whose sodium values were normal, the investigators reported. Unlike excess sodium in the blood, low sodium levels had no association with an increased risk of dying in the hospital, Tzoulis said.

Among patients with high sodium levels at any time during their hospital stay, nearly 56% died versus about 21% of patients whose sodium remained normal, the data showed.

Doctors usually treat high sodium levels with intravenous fluids, and low sodium may require intravenous fluids, fluid restriction or medications. However, both conditions are often underestimated and undertreated, Tzoulis said.

Fluid losses due to diarrhoea, vomiting, sweating, and not drinking enough water can lead to high sodium levels. Therefore, Tzoulis stressed the importance of avoiding dehydration during a hospital admission for COVID-19.

Other authors of the study include: Julian A Waung (co-first author), Aiyappa Biddanda, John Cousins, Alice Dewsnip, Kanoyin Falayi, Will McCaughran, Chloe Mullins, Ammara Naeem and Muna Nwokolo of Whittington Health NHS Trust; Emmanouil Bagkeris of Imperial College London; Eithar Deyab, Syed Bitat and Swarupini Ponnampalam of University College London Hospital NHS Foundation Trust; PierreMarc Bouloux of University College London; Hugh Montgomery of Whittington Health NHS Trust and University College London; and Ziad Hussein and Stephanie E Baldeweg of both University College London Hospital NHS Foundation Trust and University College London.

 

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

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

Published in The Journal of Clinical Endocrinology & Metabolism on 24 February 2021

Abstract
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.

 

[link url="https://www.endocrine.org/news-and-advocacy/news-room/2021/abnormal-sodium-levels-in-hospitalized-patients-with-covid-predict-death-or-respiratory-failure"]Endocrine Society material[/link]

 

[link url="https://academic.oup.com/jcem/advance-article/doi/10.1210/clinem/dgab107/6148869"]The Journal of Clinical Endocrinology & Metabolism study (Open access)[/link]

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