[Evaluation and treatment of hyponatremia (author's transl)]

In all patients with hyponatremia, an etiologic diagnosis must be made. A diagnostic classification of hyponatremic states is proposed, which is based on extracellular fluid volume status. A spot urinary sodium concentration will be helpful in confirming the diagnosis. Treatment should concentrate on correction of etiologic factors and fluid restriction after any extracellular fluid volume depletion is treated. A regimen of rapid correction of hyponatremia is outlined for serious, symptomatic cases. It consists of diuretic induced diuresis, accompanied by hypertonic sodium replacement of urinary losses. Finally, the usefulness of demeclocycline hydrochloride is characterized.