Too Much Sodium (Hypernatremia): Drug Therapy

Therapeutic targets

  • If the dehydration (lack of fluid) is based on a disease, its therapy is in the foreground (causal therapy).
  • Rehydration (fluid balance).
  • Correction of the sodium balance

Therapy recommendations

  • 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”)):
    • Thirst only: replace 2 liters
    • Additional dry skin / mucous membranes: replace 2-4 liters
    • Additionally circulatory symptoms (earliest in hypotonic dehydration) (pulse ↑, blood pressure ↓, central venous pressure (CVP) ↓): > 4 liters replace
    • Caveat:
      • 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 sodium balance (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 sodium concentration 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.
  • See also under “Further therapy“.