Prognostic value of hypocalcemia in COVID-19

Background: Preliminary data suggest that hypocalcemia is common among patients with coronavirus 2019 (COVID-19) admitted to the hospital. Objective : To examine the prognostic value of hypocalcemia in the setting of COVID-19. Methods: Literature search (Pubmed) until September 15, 2020. Search terms include hypocalcemia, COVID-19, mortality, complications. Retrospective studies are reviewed due to lack of randomized trials. Results: Hypocalcemia is the most common electrolyte abnormality in patients with COVID-19 admitted to the hospital after hyponatremia. Prevalence of hypocalcemia among hospitalized patients with COVID-19 ranges from 9.5% to 78% depending on the definition of hypocalcemia and patients’ characteristics. In most cases, hypocalcemia is mild to moderate biochemically. Hypocalcemia is a risk factor for hospitalization of patients with COVID-19. In already hospitalized patients, hypocalcemia is significantly associated with increase severity of COVID-19 and its complications including multi-organ failure, intensive care unit (ICU) admission, need for mechanical ventilation, acute respiratory distress syndrome (ARDS), and death. Hypocalcemia is significantly correlated with inflammatory markers of COVID-19. Causes of hypocalcemia in COVID-19 patients are unclear, but vitamin D deficiency may be a contributing factor. Conclusions: Hypocalcemia is common in hospitalized patients with COVID-19 and carries unfavorable outcomes. Further studies are needed to examine causes of hypocalcemia in COVID-19 and to see whether normalization of circulating calcium levels improve prognosis.