Hypokalemia Is Associated With COVID-19 Severity

Early studies reported various electrolyte abnormalities at admission in patients who later presented the severe form of coronavirus disease 2019 (COVID-19). Electrolyte imbalance may not only affect patient care, but could provide insights into the COVID-19 pathophysiology.

Hypokalemia is a low level of potassium (K⁺) in the blood serum. Mild low potassium does not typically cause symptoms. Symptoms may include feeling tired, leg cramps, weakness, and constipation. Low potassium also increases the risk of an abnormal heart rhythm, which is often too slow and can cause cardiac arrest.

Medical scientists at the Alicante General University Hospital (Alicante, Spain) carried out a retrospective cohort study of 306 patients with COVID-19 pneumonia hospitalized in an academic center of Spain. The study period was from the March 3, until May 2, 2020. COVID-19 diagnosis required a positive reverse transcriptase–polymerase chain reaction (RT-PCR) test for SARS-CoV-2, mainly in nasopharyngeal aspirates.

Laboratory data, including C-reactive protein, Procalcitonin, Ferritin, Interleukin-6, Lactate dehydrogenase, D-dimers, Troponin T and Brain natriuretic peptide, and treatments used, including diuretics, were obtained from electronic medical records during admission. The team classified the patients into groups according to the nadir of potassium levels (K⁺) in the first 72 hours of hospital admission: hypokalemia K⁺ ≤3.5 mmol/L (which includes severe hypokalemia (<3 mmol/L) and mild hypokalemia (3-3.5 mmol/L)) and normokalemia (>3.5 mmol/L).

The team reported that of the 212 patients with normokalemia, 9% required admission to the intensive care unit (ICU), compared with 30.3% of the 76 patients with mild hypokalemia and 33.3% of the 18 patients with severe hypokalemia. Need for invasive mechanical ventilation was 6.2%, 25%, and 33.3%, respectively. After adjusting for confounders, hypokalemia was independently associated with requiring invasive mechanical ventilation during admission (odds ratio = 8.98).

Hypokalemia was not associated with increased mortality, but was associated with longer hospital and ICU stay. Mortality rates were 16.2% in the normokalemia group, 15.8% in the mild hypokalemia group, and 16.7% in the severe hypokalemia group. Median time in the hospital was seven days for patients with normokalemia, 11 days for patients with mild hypokalemia, and 16.5 days for patients with severe hypokalemia. Median length of time in the ICU was 8 days, 11 days, and 15 days, respectively.

The authors concluded that this sensitive biomarker may reflect the progression of COVID-19, it is independently associated with intensive mechanical ventilation requirement after adjusting by confounders, and should be closely monitored to guide timely treatment. The study was published on September 17, 2020 in the International Journal of Infectious Diseases.

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