[Treatment of hyponatremia: new developments and controversies]

This article summarizes improvements in diagnosis and therapy in patients with symptomatic hyponatremia. The available treatment options for hyponatremia have been limited, and consisted mainly of isotonic or hypertonic saline, urea, and fluid restriction. Vasopressin receptor antagonists, also known as vaptans or aquaretics are a new class of drugs that now offer an additional treatment option for hyponatremic patients with euvolemic hyponatremia due to SIADH in Europe. In short and long term studies, tolvaptane has been shown to be effective in raising serum sodium levels in a predictable fashion in patients with SIADH with only few side effects, when serum sodium was frequently monitored and dosage of tolvaptans was properly adjusted. Further studies are needed to find out which patients benefit from treatment with respect to morbidity and mortality. Until now, therapy is limited to the treatment of moderate symptomatic hyponatremia in SIADH due to the high cost of therapy.