The pharmacologic management of the syndrome of inappropriate secretion of antidiuretic hormone.

There have been numerous treatment modalities reported in the literature concerning the acute and chronic treatment of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Water restriction remains the mainstay of therapy. However, patient noncompliance for this regimen often makes additional treatment modalities necessary. In the long-term treatment of chronic SIADH, lithium, demeclocycline, loop diuretics, and urea are helpful, regardless of the origin of the SIADH. The use of lithium is not recommended due to the incidence of digestive, cardiac, thyroid, and central nervous system side effects, as well as the demonstrated superiority of demeclocycline. Urea and loop diuretics, although shown to be effective, have not been used clinically to the extent as demeclocyline, and are not free of adverse effects. Phenytoin is limited in its use to the treatment of SIADH secondary to abnormalities of the hypothalamic-pituitary axis, and plays no role in the treatment of tumor-induced SIADH. Demeclocyline has been shown to be effective in all types of SIADH. The lack of comparative studies of long-term treatment regimens makes the selection of a regimen of choice difficult. At this point loop diuretics or demeclocycline appear to be the regimens of choice based primarily upon case reports and relatively small comparative study patient populations. Further comparative studies are needed in an attempt to identify the most efficacious regimen with the minimal incidence of adverse effects.