Potassium (K+) is the major positive ion in the intracellular space and is essential for many body functions, mainly the neuromuscular excitability. Low potassium levels in serum, or Hypokalemia, can cause fatigue, muscle cramps, constipation and cardiac arrhythmia, which can even lead to cardiac arrest. 
A pooled analysis of 1415 COVID-19 patients identified various electrolyte abnormalities at hospital admission. The report showed lower serum concentrations of potassium, as well as sodium and calcium in patients with a severe disease progression. 
Further, a retrospective cohort study of 306 patients with COVID-19 pneumonia found that even though Hypokalemia was not associated with an increased mortality rate, it was associated with longer hospital and ICU stays. The researchers showed that serum K+ levels lower than 3.5 mmol/L were an independent predictor of invasive mechanical ventilation requirement. In conclusion, potassium seems to be a sensitive biomarker of severe progression in patients with COVID-19 pneumonia. Therefore, close monitoring of the parameter is advised for COVID-19 pneumonia patients in order to ensure timely treatment. 
DiaSys offers a photometric alternative for potassium measurement on clinical chemistry analyzers. For more information, please follow the link:
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- Lippi G, Andrew MS, Brandon MH. Electrolyte imbalances in patients with severe coronavirus disease 2019 (COVID-19). Annals of Clinical Biochemistry 57.3 (2020): 262-265
- Moreno-P O, et al. Hypokalemia as a sensitive biomarker of disease severity and the requirement for invasive mechanical ventilation requirement in COVID-19 pneumonia: A case series of 306 Mediterranean patients. International Journal of Infectious Diseases 100 (2020): 449-454.