Urine and Plasma Osmolality in Diagnosis and Management of Dilutional Hyponatremia

Abstract

In a number of different clinical settings, including therapy with certain drugs, dilutional hyponatremia is related to excessive antidiuretic hormone. A hormone-producing tumor, particularly lung carcinoma, is the most common underlying disease in patients with the “inappropriate ADH syndrome.” Water-loading studies with determinations of urine and plasma osmolality are useful in following the course of this syndrome, as shown by the illustrative cases presented.