Sodium Status and Its Correlation with Indices of Pulmonary Dysfunction in COVID-19 Patients

Abstract

Background: COVID-19-induced hyponatremia is reportedly associated with pulmonary dysfunction, but mostly among Caucasians. Hence, the current study evaluated sodium status and its correlation with indices of pulmonary dysfunctions among Nigerians of Negroid race. Methods: This was a retrospectively-designed observational study. Data, all obtained at presentation, were acquired from medical records of 480 RT-PCR-confirmed COVID-19 patients managed at a COVID-19-designated treatment facility in Port Harcourt, Southern Nigeria. Analysis of acquired data was done by COVID-19 clinical grades and sodium status using descriptive and inferential statistics. Results: At presentation, hyponatremia and hypernatremia were observed in 47.7% and 1.0% of the entire studied cohorts (n=480), respectively. Both disorders (hyponatremia/hypernatremia) were mostly observed among the moderate, severe, and critical cases. Most hyponatremic cases (n=154;67.2%) and the entire hypernatremic cases (n=5;100%) were of mild grades. Hyponatremics had higher proportions of fever, breathlessness, confusion, and a higher burden of inflammatory markers which increased with worsening hyponatremic grade. Etiologically, hyponatremia was mostly associated with the syndrome of inappropriate anti-diuretic hormone secretion (SIADH) (n=132;56.7%). Among the hyponatremics, an inverse correlation existed between sodium and respiratory rate (RR), while a correlation existed between sodium and oxygen saturation (SpO2). Compared to mild hyponatremics, the moderate/severe hyponatremics had a greater risk of having RR>30 and SpO2 <95%.  Conclusion: Hyponatremia, mostly of mild grade, was common among the studied COVID-19 patients and was associated with indices of pulmonary dysfunctions, including disease severity, inflammatory markers, and SIADH. Hence, hyponatremia should be utilized to triage COVID-19 patients at presentation. However, further studies are recommended to verify these findings.