AVP and inappropriate ADH syndrome: The underlying mechanism for the hyponatremia in COVID-19 is supposed to be related to low intake due to anorexia, excretion of sodium from skin through sweating, loss of sodium from the gastrointestinal system due to vomiting or diarrhea, increased excretion of sodium from kidney due to the use of diuretic drugs or decreased excretion of water from kidney due to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH).