In cases of hypernatremia due to loss of free water, copious drinking is usually sufficient.
Rehydration: in more severe cases of dehydration in the form of parenteral rehydration (infusions) – based on an estimate of water loss (the following example: adult, 70 kg) and based on symptoms (“favor physiological route”, i.e. enteral water administration (“via the intestine”)):
In case of exsiccosis (“dehydration“), do not administer plasma expanders (colloidal solutions whose osmotic pressure is greater than that of blood plasma)! They would increase the extravascular fluid deficit.
Cautious water substitution in cardiac or renal insufficiency (heart and kidney failure) → control CVD and body weight (pulmonary edema!).
Correction of sodiumbalance (note: chronic hypernatremia should be corrected slowly initially, acute ones can be treated briskly).
Isotonic dehydration (“dehydration”).
Supply of isotonic or isoionic fluid (e.g., Ringer’s solution: isotonic electrolyte solution for intravenous infusion).
Hypertonic dehydration
Supply of osmotically free water (5% glucose solution; after metabolization (metabolization) of glucose, only free water remains) and replacement of one-third of the fluid deficit with isotonic or isoionic electrolyte fluid.
Caveat: In chronic hypernatremia (over a period of at least 4 days), the brain has adapted to hyperosmolality in the extracellular space. Too rapid correction may result in cerebral hyperhydration with cerebral edema (brain swelling). Rule of thumb: normalize sodiumconcentration by about 0.5 mmol/l/hour over a period of 48 hours.
Hypertonic hyperhydration (“overhydration”).
In the presence of hypervolemia, loop diuretics are primarily used
In case of pronounced desiccosis (“dehydration”): infusion of an isotonic electrolyte solution.
In the presence of diabetes insipidus see below the disease of the same name.