Dysnatremia increases risk for poor COVID-19 outcomes, mortality
Abnormal sodium levels are associated with a higher risk for mechanical ventilation and mortality in adults hospitalized with COVID-19, according to data presented at the ENDO annual meeting.
“Both low and high sodium levels in the blood are markers of poor prognosis in patients with COVID-19,” Ploutarchos Tzoulis, MD, PhD, FRCP (UK), MSc (Hons), an honorary associate professor in endocrinology at University College London Medical School, told Healio. “Patients who present to the hospital with COVID-19 and low sodium levels are twice as likely to develop respiratory failure and need advanced ventilatory support, such as intubation and mechanical ventilation, in comparison to those with normal sodium. In addition, patients with COVID-19 who develop high sodium concentration at any time point during their hospital stay have a threefold increase in the likelihood to die compared to those with normal sodium levels.”
Tzoulis and colleagues conducted a retrospective longitudinal study of all adults who tested positive for COVID-19 and were admitted to Whittington Hospital and the University College London Hospitals NHS Foundation Trust in London during an 8-week period from February to May 2020. Data were collected from electronic medical records, pathology records and discharge summaries. Primary outcomes were inpatient mortality and the need for advanced respiratory support. Hyponatremia was defined as serum sodium less than 135 mmol/L, and sodium of greater than 145 mmol/L was defined as hypernatremia. Mild hyponatremia was for adults with sodium of 130 mmol/L to 134 mmol/L, and moderate to severe hyponatremia included patients with a sodium level of less than 130 mmol/L.
Dysnatremia increases risk for poor COVID-19 outcomes
There were 488 adults included in the study (56.8% men; median age, 68 years). Preexisting hyponatremia was prevalent in 5.1% of patients before hospital admission. At presentation, 5.3% of the study cohort had hypernatremia and 24.6% had hyponatremia. Of those with hyponatremia, 18.4% fell into the mild category and 6.2% had moderate to severe hyponatremia. Only 19% of people with moderate to severe hyponatremia had an adequate laboratory assessment for hyponatremia. Of adults with a hyponatremia laboratory assessment, 75% were classified as having hypovolemic hyponatremia and the remaining 25% had non-hypovolemic hyponatremia.
Those with hypernatremia had an increased risk for death compared with patients with normal sodium levels (adjusted HR = 2.74; 95% CI, 1.16-6.4; P = .02). There was no association between hyponatremia and mortality; however, hyponatremia increased the likelihood for ventilatory support compared with patients with normal sodium (OR = 2.18; 95% CI, 1.34-3.46 P = .0011).
Sodium levels increased in patients during their hospitalization. The prevalence of hyponatremia decreased from 24.6% at baseline to 14.1% at 5 days after hospitalization, whereas hypernatremia increased from 5.3% at baseline to 13.8% at day 5.
Using sodium as a marker for COVID-19 risk
“Our study can have direct impact on patient care since it provides doctors with another useful and easy-to-use tool in terms of classifying patients’ risk for severe illness, need for advanced ventilatory support and death,” Tzoulis said. “As a result, sodium levels can potentially improve clinical decision-making and help doctors make key decisions, for example, about whether a patient needs hospital admission or not. The second implication of our study is that it provides strong evidence that ‘conservative’ fluid resuscitation regimens can be detrimental for patients’ health and clinical progress, supporting more ‘aggressive’ rehydration strategies.”
Tzoulis said further research is needed to examine the implications of prompt correction of abnormal sodium concentration and the potential role of low sodium as a marker to identify people at high risk for severe illness.
Reference:
- Tzoulis P, et al. J Clin Endocrinol Metab. 2021;doi: 10.1210/clinem/dgab107.
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Tzoulis P, et al. Longitudinal study of prevalence of sodium abnormalities in hospitalized patients with COVID-19. Presented at: ENDO annual meeting; March 20-23, 2021 (virtual meeting).
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