Hyponatremia in Coronavirus Disease-19 Patients: A Retrospective Analysis

Abstract

Background: Hyponatremia (serum Na⁺ < 135 mmol/L) is the most common electrolyte abnormality detected in clinical practice and an important cause of mortality and morbidity in hospital settings. Hyponatremia in patients with pneumonia is usually mild but is associated with increased risk of intensive care unit (ICU) admission, prolonged hospital stays, and increased mortality rates. The purpose of this study is to understand the impact of varying degrees of hyponatremia and various other inflammatory markers on the severity and outcome of coronavirus disease-19 (COVID-19).

Objective: The main objective of this study is to evaluate the prevalence of hyponatremia in COVID-19 patients and to assess the correlation between hyponatremia and severity and outcome of COVID-19. The other objective is to evaluate the correlation between various inflammatory markers and outcome (ICU vs non-ICU admission, discharged vs deceased) in patients with COVID-19 pneumonia.

Methods: A total of 113 participants who have been diagnosed with COVID-19 infection by reverse transcriptase-polymerase chain reaction test were included in the study. Epidemiological, demographic, clinical, investigative work-up, and outcome data were extracted from electronic health records using a standard data collection form. Based on serum sodium levels, patients were divided into two groups: normonatremic (serum Na⁺ ≥ 135 mEq/L) and hyponatremic (serum Na⁺ < 135 mEq/L). Various clinical, laboratory, and outcome parameters were compared between the two groups.

Results: Hyponatremia was present in 50 out of 113 (44%) patients in our study, and it was generally mild. There were more male patients in hyponatremia group (P = .006), and hyponatremic patients were older than normonatremic patients (P = .001). Forty (35%) of the 113 patients were transferred to the ICU, and 17 (15%) needed mechanical ventilation during their hospitalization. Interleukin-6 (IL-6) levels were higher in the hyponatremic group (P = .022). Intensive care unit admissions and oxygen requirement were significantly higher in hyponatremic patients (P = .001 and .016, respectively). Ferritin, lactate dehydrogenase (LDH), IL-6, total leucocyte count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were significantly elevated in those patients requiring ICU admission and those who died due to COVID-19.

Conclusions: Our study revealed that demography, clinical features, radiographic findings, complications like renal insufficiency, and inflammatory markers like IL-6 play a considerable role in hyponatremic COVID-19 patients. Hyponatremia patients required significantly higher rates of ICU admissions and oxygen support. Our results suggest that monitoring inflammatory markers such as ESR, CRP, total white blood cell (WBC) count, ferritin, LDH, and IL-6 may serve as an early warning system for progression to severe COVID-19.

Keywords: COVID-19; IL-6; SARS-CoV-2; coronavirus; hyponatremia.

Figure 1.

A bar diagram showing most frequent symptoms in our cohort. Note. GI = gastrointestinal; SOB = shortness of breath.

Figure 2.

Box-plot showing the comparison of lymphocyte counts (cells/mm³) between hyponatremic and normonatremic patients. Note. ALC = absolute lymphocyte count.

Figure 3.

Scatter diagram showing the association between Na⁺ (mEq/L) and IL-6 (pg/mL). Note. IL-6 = interleukin-6.

Figure 4.

Error bar showing the comparison between IL-6 (pg/mL), ferritin (ng/mL), and LDH (U/L) in hyponatremic and normonatremic patients. Note. IL-6 = interleukin-6; LDH = lactate dehydrogenase; CI = confidence interval.

Figure 5.

Box-plots showing total white blood cells count (cells/mm³), ESR (mm/h), and CRP (mg/L) versus outcome, respectively. Note. ESR = erythrocyte sedimentation rate; CRP = C-reactive protein; TC = total leucocyte count.