Low serum calcium: a new, important indicator of COVID-19 patients from mild/moderate to severe/critical

Abstract

Background: Coronavirus disease 2019 (COVID-19) virus is still spreading, finding out the initial hits of viral infection is important to minimize the mild/moderate population, prevent disease aggravation and organs dysfunction. Objective: We investigated COVID-19 patients with different serum calcium levels.

Design: We checked the serum calcium level of the patients based on days after symptom onset as well as the severity of COVID-19. We also checkeed multi-organ injuries and immune cytokines level in their blood.

Results: Both mild/moderate and severe critical cases we observed showed low calcium level in the early stage of viral infection, while the severe/critical cases showed significant lower calcium level than mild/moderate cases in the early stage. We also found that low calcium level related to severe/critical multi-organ injuries especially in the mild/moderate population. Proinflammatory cytokine IL-6 also correlated to calcium change in both mild/moderate and severe/critical cases.

Conclusions: Our finding indicates that calcium balance is a primal hit of COVID-19 and a biomarker of clinical severity at the beginning of symptom onset. Calcium is closely associated with virus-associated multiple organ injuryes and the increase of inflammatory cytokines. Our results provide a new, important indicator of COVID-19 patients from mild/moderate to severe/critical: serum calcium.

Keywords: COVID-19; Multi-organ injury; Pro-inflammatory cytokine; Serum calcium.

Conflict of interest statement

The authors declare that there are no competing interests associated with the manuscript.

Copyright 2020 The Author(s).

Figures

Figure 1. The association between serum calcium in COVID-19 patients with disease severity, age and days after symptom onset

Independent group t test was used to compare the means for continuous variables. A P-value of less than 0.05 was considered to be statistically significant with a two-sided alternative. (A–D) Various kinds of serum ions (a. potassium ion; b. sodium ion; c. chloride ion; d. calcium ion) concentrations in COVID-19 patients vary with the number of days after symptom onset. (E) Calcium level in COVID-19 patients grouped by severity of illness. (F) Low calcium and normal patients age distribution (normal (serum calcium concentration ≥ 2.2 mmol/l), low (serum calcium concentration < 2.2 mmol/l). (G) Calcium level in mild/moderate and severe/critical COVID-19 patients vary with the number of days after symptom onset. (H) The age distribution of mild/moderate and severe/critical cases in different timing after symptom onset was checked.

Figure 2. The calcium level in the patients with or without coexisting disorder

(A) The calcium level in the patients with or without coexisting disorder. (B,C) Patients were divided into five groups (no underlying diseases, hypertension+others, hypertension+diabetes, diabetes+others, others) and measured the calcium level (B) and the age distribution (C) separately for each group. (D,E) When we exclude the patients with hypertension plus with diabetes, the calcium level in mild/moderate and severe/critical COVID-19 patients vary with the number of days after symptom onset (D) and the age distribution of mild/moderate and severe/critical cases in different timing after symptom onset was checked (E).