Sodium disorder is a volume disorder since sodium is predominantly extracellular (ECF) ion. You cannot only change sodium level without changing volume in our body. It is critical to understand mechanism to control water and sodium in kidney: water and sodium are handled separately in different channels (NHE3, NKCC2, NCC, ENaC) and different hormones regulate volume and sodium (Aldosterone, ADH). Hypernatremia is prevented by our sense of thirst. Hyponatremia is common among hospitalized patients while hypernatremia is more ominous than hyponatremia. And hyponatremia is biphasic illness: hyponatremia encephalopathy and ODS. You must remember Na contents of infusate you use for correction. Remember ‘rule of 6’ for correction.