Elevated Serum Sodium at Hospital Admission for SARS-CoV-2 May Indicate Increased Risk for Severe Diseases and Mortality

Serum sodium may be an effective risk stratification marker for severe illness with SARS-CoV-2. These findings, from a retrospective longitudinal cohort study, were published in the Journal of Clinical Endocrinology and Metabolism.

Patients (N=488) with SARS-CoV-2 hospitalized between February and May, 2020, at Whittington Hospital or University College London Hospital in the United Kingdom were assessed for clinical characteristics and outcomes of disease.

At baseline, 56.8% of patients were men aged a median 68 years (interquartile range [IQR], 56-80), 24.5% of patients had at least 3 comorbidities, and 23.9% of patients had 2 comorbidities. The most common coexisting conditions included hypertension (45.7%), diabetes (25.0%), advanced chronic kidney disease (16.4%), asthma (11.9%), and ischemic heart disease (11.3%).

Stratified by survival, the patients who died from SARS-CoV-2 were more likely to be men (P <.005), be older (P <.0001), be current or former smokers (P <.05), have advanced chronic kidney disease (P =.0016), and have active cancer (P =.0014), whereas patients who were White (P <.0001) or have chronic hyponatremia (P =.0019) were less likely to die.

Compared with survivors, individuals who died had elevated urea (median, 8.8 mmol/L; IQR, 5.7-14.8; P <.0001), creatinine (median, 104 mmol/L; IQR, 74-162; P <.0001), C-reactive protein (median, 11.7 nmol/L; IQR, 6.7-19.9; P <.0001), high sensitivity troponin-T (median, 0.028 ng/mL; IQR, 0.017-0.054; P <.0001), potassium (median, 4.3 mmol/L; IQR, 3.93-4.7; P =.0008), neutrophil count (median, 6.2 x 10⁹/L; IQR, 3.87-9.00; P =.04), and glucose (median, 6.9 mmol/L; IQR, 5.95-9.10; P =.0045).

Patients who died also had decreased albumin (median, 36 g/L; IQR, 33-38; P <.0001), lymphocyte count (median, 0.8 x 10⁹/L; IQR, 0.60-1.23; P =.0004), and hemoglobin (median, 123 g/L; IQR, 109-136; P =.0096) compared with survivors.

Among all patients, both sodium (P <.001) and urea (P =.01) concentrations increased over the duration of hospitalization.

In-hospital mortality was associated with increased C-reactive protein (adjusted hazard ratio [aHR], 1.10; 95% CI, 1.04-1.17; P <.001), age (aHR, 1.04; 95% CI, 1.01-1.07; P =.007), and hypernatremia (aHR, 2.74; 95% CI, 1.16-6.40; P =.02).

The serum sodium status 2 days after hospitalization was associated with mortality; patients who had hypernatremia had a 2.34-fold increased risk of death (P <.005) than normonatremic individuals. Patients who had a hypernatremia or a history of either hypernatremia or hyponatremia were at 3.05-fold (P <.0001) and 2.25-fold (P =.0038) increased risk for mortality, respectively.

This study was limited investigators not having access to data about care received during hospitalization.

These data indicated elevated serum sodium concentration at hospital admission for COVID-19 were associated with increased risk for hospital mortality and may be a valuable marker for patients at high risk for severe illness.

Reference

Tzoulis P, Waung J A, Bagkeris E, et al. Dysnatremia is a predictor for morbidity and mortality in hospitalized patients with COVID-19. J Clin Endocrinol Metab. 2021;dgab107. doi:10.1210/clinem/dgab107.