The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which may involve multiple organ systems. Acute kidney injury (AKI) has been widely reported with COVID-19, however other manifestations including electrolyte disturbances have been less well described. Evidence suggests that changes in serum sodium, potassium, chloride and calcium may be associated with infection as well as disease severity. 

A recent study assessed data from 10385 patients hospitalized with COVID-19 to evaluate the prevalence at hospital presentation of the full spectrum of electrolyte disorders. 

• Most serum electrolytes showed overall missingness of ≤0.1%, while serum magnesium and serum phosphorus showed substantial missingness (28.5% and 39.8%, respectively). Hyponatremia was the most commonly identified disorder (37.5%), followed by hypochloremia (26.0%) and hypocalcemia (18.3%). 
• In patients with a calculated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2, hyponatremia, hyperkalemia, hypochloremia and hypocalcemia were seen in 30.3%, 11.1%, 19.7% and 19.2%, respectively. Hyperphosphatemia (13.9%) and hypermagnesemia (12.2%) were observed in a minority; however, a significant amount of data was missing (37.4% and 26.2%, respectively) for this group.
• Kidney transplant patients most frequently suffered from hyponatremia (42.4%), hyperkalemia (16.7%) and hypochloremia (19%). Hypophosphatemia (16.7%), hypomagnesemia (15.2%) and hypocalcemia (12.1%) were common in this group, however, many patients did not go for electrolytes evaluation (25.8%, 19.7% and 1.5%, respectively).
• Patients with end-stage kidney disease (ESKD) mostly described hyponatremia (40.9%), hyperkalemia (23.4%) and hypochloremia (62%), along with Hyperphosphatemia (45.7%), hypermagnesemia (8.4%) and hypocalcemia (27.8%) (missingness of 26.8%, 23.2% and 0.2%, respectively).
• Many patients showed numerous co-occurring electrolyte disorders at presentation. 
• On examining only electrolytes with ≤0.1% missingness (except magnesium and phosphorus), only 32.7% showed completely normal electrolytes on admission. 
• Patients with electrolyte abnormalities, frequently had hyponatremia and hypochloremia together (12.4%), followed by hyponatremia alone (11.1%). 

This was the first and largest study to assess all electrolyte disorders noted in hospitalized patients with COVID-19. Hyponatremia was the most prevailing electrolyte abnormality, followed by hypochloremia and hypocalcemia. 

Source: Clinical Kidney Journal, June 2021;14(6): 1704–1707. https://doi.org/10.1093/ckj/sfab060